Teacher`s Section - Earth Science Teachers` Association

EARTH SCIENCE
EXPERIMENTS
for
A level
Mike Tuke
1
Welcome to “Earth Science experiments for A
level”. This was originally produced as a CD.
You will find it much easier if you read the chapter
“How to use these experiments” before doing any of
the experiments. Then choose an experiment from
the simple list on page 11 or the more detailed list
on page 15 which describes the purpose of each
experiment.
The first page of each experiment gives the purpose
and instructions for students. The teacher’s section
for each experiment lists the equipment needed and
instructions for setting up the experiment. You may
find it easier to understand the experiments if you
print off the relevant pages. This will save you
scrolling up and down between the instructions, the
diagrams, photos and the requirements list. It is
easiest if the teacher collects and sets up the
apparatus prior to the lesson.
Copyright
© Mike Tuke 2007
You may copy or print pages from this manual without fee or
prior notice provided it is for non-commercial educational
purposes in schools or other educational institutions.
Permission from the author must be sought to reproduce
material from this manual in other publications and appropriate
acknowledgement must be given.
2
Contents
Introduction
4
How to use these experiments
6
List of experiments
11
List of experiments with the purpose of each
15
The experiments
24
Appendices
1 Making equipment
292
2 Suggested topics to be covered in writing up a full experimental
report
300
3 List of books and journals with geological experiments
302
4 List of sources of materials and equipment
303
5 List of equipment available in the lab
306
6 References
306
7 Photocopying rocks
306
About the author
307
3
Introduction
This is a collection of experiments designed for use by A level and degree
students. The purpose of these experiments is above all to help students
learn some geology but it is also for students
to see geological processes or simulations of them
to make deductions from the data they have collected
to learn the experimental skills of observation and measurement
to develop skills of evaluating the reliability, accuracy and validity
of experiments.
Nearly all the experiments use materials and equipment that will be found
in most science labs or can be acquired cheaply from hardware shops and
gardens centres etc.
All the experiments have been tried and tested on A level students or
mature students on Access courses or in evening classes, and some on
degree students. Some experiments have been used every year for the
past 30 years and all have been used on several occasions.
The range of experiments covers most aspects of geology. There are
many for sedimentology and structural geology because it is easy to
devise experiments to illustrate aspects of these subjects but fewer for
metamorphic processes because it is difficult to illustrate this subject
with simple experiments.
These experiments were not designed as demonstrations but many of
them can be used as such with little modification, providing that it is to
groups of less than 15.
Why do experiments
Experiments make students think and thus are an effective way of
learning, much more so than “chalk and talk”. They add variety to lessons.
Discussion is a very effective way of learning and experiments are, in my
experience, the most effective way to encourage discussion in Geology
classes, both before on how to carry out the experiment and its
geological relevance, and after, in drawing conclusions and evaluating the
results.
Experiments can be used to reinforce information given in class or can be
used to lead into a topic. Students also generally enjoy doing experiments.
4
Sources of experiments
Some experiments have been adapted from articles in Teaching Earth
Science or other sources with only minor adjustments. In this case I
have credited the author. Some are based on other people’s ideas but
significantly modified by me. Most of the experiments are, however,
original.
Thanks
Thanks are due to my wife, Jean, who has long accepted the triumph of
geology over domestic life and without whose saintliness many of these
experiments would not have been developed. She has coped, with only the
occasional outburst, with rocks in her freezer, variously coloured liquids
in her fridge and experimental apparatus cluttering the kitchen table and
units, She has come home to find the sink covered with sand grains and
the oven full of aluminium blocks and, even worse, not being able to put
her beloved 2CV in the garage because I had taken it over for geology
experiments.
I am also indebted to my students who have been guinea pigs and who
have made many suggestions for improvements.
Elizabeth Devon has read through the manuscript and made many useful
suggestions.
The costs involved in reviewing, duplication and distribution of this CD
were paid for from a grant kindly given to ESTA by the Petroleum
Exploration Society of Great Britain.
5
HOW TO USE THESE EXPERIMENTS
General
These experiments are designed to be done by pairs of students but
many can be done by individual students.
You can either run the experiments as they are simply by printing out the
instruction sheet or, better, you can modify the instructions to suit your
own teaching.
Any room with enough table or bench space is suitable. Some
experiments use mains electricity and therefore require a power point.
Water is often needed and lab with running water and a sink is certainly
convenient but all experiments could be done without this. Mains gas is
never needed.
The instructions assume that all the equipment is already put out and set
up before the students start. I have found this is the easiest way to work
and saves time.
All these experiments have worked well for my students but it would be a
wise precaution to try them out yourself before inflicting them on your
own students.
Before the experiment
It is generally a good idea to discuss the experiment with students
before they start it, to enlarge upon its purpose and to think about its
geological relevance, what are the variables and what aspects are
controlled, what needs to be recorded and how, how the experiment
relates to what is being taught in lectures and any safety aspects.
Encouraging students to devise an experiment to solve a particular
problem is an effective way of keeping them interested and making them
think. They can then, after discussion, do an appropriate experiment from
this book. They can then evaluate the pros and cons of their own method
and the one in this book. Students should sometimes be asked to write
hypotheses. If they do there should always be a rationale for their
hypothesis otherwise it is just a guess.
After the experiment
At the end of every experiment students should be able to draw a
conclusion or make a statement about the results. They should also
6
evaluate the results. Class discussion of the results and evaluation of the
accuracy, reliability and validity of the experiment is also productive.
It is not always necessary for students to write a full formal report.
Depending on the circumstances you may wish the students:
Just to write down their conclusions
To write down the purpose, relevance and conclusions with or
without evaluation
To do a full formal report. A list of topics which students should
address for a full report is given in appendix 2
Slavishly copying out the method is not usually a good use of student
time.
Getting students to answer questions which use the results is a very
successful way of ensuring they learn from the experiment.
Safety
There are no significant hazards with any of these experiments. I have
not had any injuries in my class yet (touch wood) in spite of teaching
Geology for 35 years and having spent nearly half of many lessons doing
practical activities. However students should be aware of the dangers of
boiling water, heavy rocks rolling off tables, blown sand and the danger of
shock if electrical apparatus is not handled properly in the especially
presence of water.
The Headings
Each experiment has several headings. These are explained below. The
first page(s) are the student instructions. The teacher’s section follows.
Purpose
This is a simple statement to inform the student why they are doing the
experiment and what they should find out from it. It is very important
that the student understands the purpose of the experiment and how it
relates to the theory being taught in class. Class discussion of the
purpose and geological relevance is always helpful.
Where the variables are given it is assumed that other factors will be
held constant.
7
Activities
In some experiments there is only one activity whereas in others there
are several related activities. It is not necessary for every student to do
all the activities for a given experiment. Pairs of students can each do
one activity and then report back their results to the class. Alternatively
just one of the activities can be chosen, usually the first is the best if
only one is to be done.
Instructions
Each activity has its own set of instructions. Where the instructions for
the second activity are very similar to the first then only abbreviated
instructions are given to save space. Teachers may want to write out
these in full so that there is an appropriate set of instructions beside
each piece of apparatus. This is particularly important if students are not
all doing the activities in order.
The sheets give instructions for doing the experiments but not on how it
should be written up.
Questions
Several sheets have questions attached so the students can use the
information they have found. This is a good way of showing students how
the information can be used and of reinforcing the information.
Requirements
The list given is for one pair of students. Most equipment should be found
in any reasonable Science Lab or be easily purchased. Where it is
necessary to buy equipment then the source is given. A list of sources is
also given in appendix 4. The exact size is never important. Some pieces
of equipment will need to be made (see below).
It is assumed that students will come with calculators and rulers and that
graph paper or lab books will be supplied. (see appendix 5 “useful
equipment to keep in the classroom”.)
Making the equipment
Some experiments require equipment to be made. Where this involves
more than cutting wood to size then separate instructions are given under
this heading. Anybody who is at all handy could make these things or they
could be made in the school or college workshop or by the technician.
Some techniques used to make pieces of equipment used in several
experiments are given in appendix 1. The time given assumes all tools and
8
materials are to hand. Remember that collecting the materials often
takes longer than making the equipment.
Notes
This covers many separate aspects: hints on running the experiment and
problems that may be encountered, alternative ways of running the
experiment or alternative pieces of apparatus, other similar or related
experiments and sources of further information.
Checks
This gives the things that you need to check that the students are doing
properly. This is only given if it is something specific to that experiment
or if it is something I have found is commonly done wrongly by students.
It is expected that teachers will check that students are using the
apparatus correctly and that they are recording their data properly. In
spite of the instructions sometimes students fail to record all the
necessary data and this may invalidate their results. Regular checking
prevents students from becoming slap dash.
Results
These are the usual results that my students have obtained and they
should give you an idea of what to expect. However you should expect
some variation because you may be using slightly different materials and
apparatus. Results are not given when they depend on the rock you are
using e.g. porosity of pumice.
It also includes the important points that students should mention in
their evaluation.
Cost
The cost is given of any item that you are likely to have to buy which cost
more that £5 in 2005.
Time
All the experiments take between 15 minutes and 75 minutes. The figure
given is the approximate time taken by students to do the experiments
and to record all necessary data. It obviously varies with the ability and
enthusiasm of the student. For most experiments the setting up time is
less than 5 minutes. It does not include the time taken to write up the
experiment or to draw any graphs.
9
References
References are only given where there is a useful source of information
which may not be generally known about.
Geological relevance
This is an important aspect of any experiment but has not been put on the
student instruction sheet because often it is good for the student to
work it out for himself.
It is only given here when it is not obvious from the purpose. Some
experiments have fairly limited geological relevance whereas others such
as porosity and permeability affect almost all aspects of geology.
Original data sheets
One of the difficulties of experimental work is getting the students to
record their data clearly and in sufficient detail with all the units named.
Unless carefully supervised, students produce rough and untidy sheets
which they then rewrite to produce a neat copy. To avoid this rewriting of
data my students are each given one sheet of pink lined paper. They must
use this to record their data on and then hand it in with their write-up.
Thought experiments
You can use this book as a source of thought experiments. You can, for
instance, get students to think of the factors which effect speed of
settling and to write hypotheses and to suggest how they could be tested.
This process often leads to good discussions.
Helpline
If you have problems with any experiment you are welcome to email me
([email protected]) with your problem and or your telephone
number and I will try to help.
10
LIST OF EXPERIMENTS
(A list with the purpose of each is given on page 15)
Minerals
Atomic mass and density
24
Igneous
Alignment of phenocrysts
Cooling and crystal size
Cooling in a liquid
Crystallisation of mixtures
Gravity settling
Investigating the properties of igneous rocks
Modal analysis and density
Speed of cooling of an igneous body
Speed of eruption
Speed of lava flows
Study of a slab of Quartz Porphyry
The porosity of pumice
Vesicular basalt
26
30
32
35
37
41
43
46
51
52
55
57
59
Metamorphic rocks
Andalusite slate
Metamorphic aureole
61
63
The transport and deposition of sediments
Desert sand
Falling grains
Flocculation
Movement of grains
Scree slopes
Speed of turbidity currents
Transport by wind
68
70
73
77
80
84
87
Sedimentary rocks
Compaction
Purity of limestones
The shape of pebbles
The sizes of pebbles
90
92
94
96
11
Sedimentary structures
Imbrication
Mudcracks
Rain prints
99
102
105
Structure
Artificial outcrops
Fold wavelength
Omission and repetition
Simple shear I
Simple shear II
Slip between beds during concentric folding
Squeezing plasticine
Stress and strain
Wavelength
107
111
116
120
123
126
131
133
137
Palaeontology
Ammonoid sutures
Anterior margin
Crenulation
Crinoidal limestone
The evolution of Micraster
Evolution using dice
Evolution using screws and nails
Extinction and continental drift
Measuring bivalves
Orientation of belemnites
Shaking shells
Shells as way-up indicators
Spines
139
141
144
147
148
150
152
154
157
159
160
162
165
12
Vertebrates
Human evolution
Dinosaur footprints
Weighing a dinosaur
169
174
176
Stratigraphy
Environmental interpretation of sands
Half lives
178
180
Economic Geology: Ore deposits and prospecting
Boreholes
182
Gaps caused by normal faulting
185
Ore grade
188
Placer deposits
190
Resistivity of rocks and minerals
196
Economic Geology: Construction and stability of the land
Angle of rest
198
Landslides
202
Landslides and stress
207
Roadstone
209
Strength of aggregate
211
Strength of Rocks I
215
Strength of rocks II
218
Subsidence due to clay shrinkage
220
Subsidence due to mining
222
Economic Geology: Energy
Hot rock
228
13
Water
Porosity of sediment
Dry porosity
Porosity of rocks
Flow of oil and water
Coefficient of permeability
Darcy’s laws of permeability
Capillary movement
Purifying water
Contaminated aquifer
The rise and fall of the water table
233
236
239
241
246
249
253
256
257
259
Earth
Earthquake
The effect of earthquakes on buildings
The shadow zone
Isostasy
The effects of isostasy
Sea floor spreading
Accretionary prism
262
267
270
273
277
284
287
Other
Meteorite craters
289
14
LIST OF THE EXPERIMENTS WITH PURPOSE
Minerals
Atomic mass and density
24
To determine the relationship between atomic weight and density
in isomorphous minerals
Igneous
Alignment of phenocrysts
26
To show what causes phenocrysts to become aligned.
Cooling and crystal size
30
To show the relationship between speed of cooling and crystal size.
Cooling in a liquid
32
To show how the temperature changes in the centre and edge of a
cooling and crystallising liquid.
Crystallisation of mixtures
35
To measure the temperature of crystallisation of salol and thymol
both as pure substances and as mixtures and to plot a phase
diagram.
Gravity settling
37
To measure the speed of settling of olivine, augite and plagioclase
and to calculate the speed of settling in basic and acid magma
Investigating the properties of igneous rocks
41
To see of there is any relationship between density, grain size and
percentage of dark minerals in igneous rocks.
Modal analysis and density
43
To use point counting to work out the modal analysis and then to
use this information to calculate the density of the rock.
Speed of cooling of an igneous body
46
To determine how size, shape, surface area, composition and grain
size affects the speed of cooling of an igneous body.
Speed of eruption
51
To calculate the speed of the landslide and of the eruption cloud
of Mount St. Helens.
Speed of lava flows
52
To determine the relationship of temperature, water content,
crystal content and angle of slope to the speed of a lava flow.
15
Study of a slab of Quartz Porphyry
55
To determine the size, percentage and orientation of phenocrysts
The porosity of pumice
57
To determine the porosity of pumice and to determine how much
the volcanic glass has been expanded by the exsolution of gas.
Vesicular basalt
59
To find the percentage of vesicles and thus the porosity of a slab
of vesicular basalt.
Metamorphic rocks
Andalusite slate
61
To see if there is any preferred orientation to andalusite crystals
in andalusite slate.
Metamorphic aureole
63
To show how the temperature changes in the rocks adjacent to an
intrusion as the intrusion cools.
The transport and deposition of sediments
Desert sand
68
To explain why sand grains that have been transported by wind are
generally better rounded than those transported by water.
Falling grains
70
To determine the effect of size, density, roundness and sphericity
on the speed of fall of grains in water.
Flocculation
73
To determine which salts in sea water cause clay to flocculate and
the effect of changing the percentage of sodium chloride.
Movement of grains
77
To determine the effect of shape, size, bed roughness and bed
slope on the movement of grains.
Scree slopes
80
To determine how size, and height of fall affect the distance a
particle moves down a scree slope.
Speed of turbidity currents
84
To see how density, volume and temperature affect the speed of
turbidity currents.
16
Transport by wind
87
To explain how size, shape and density affect the ease with which
grains can be moved by wind.
Sedimentary rocks
Compaction
90
To determine the effects of grain size and pressure on the amount
of compaction of loose sand.
Purity of limestones
92
To determine whether there is a relationship between the colour
of a limestone and the amount of impurities it contains.
The shape of pebbles
94
To see if the shape of pebbles is controlled by the bedding planes.
The sizes of pebbles
96
To determine how the sizes of pebbles seen in section on a flat
surface relate to their actual sizes.
Sedimentary structures
Imbrication
99
To determine the effect of water movement on the arrangement
of flat pebbles and to use this to deduce the direction of water
flow in sedimentary deposits.
Mud cracks
102
To study the formation of mud cracks, to determine what controls
their size and to see how modern mud cracks compare with fossil
ones.
Rain prints
105
To study the formation of rain prints and to work out the
conditions under which they form and may be preserved.
17
Structure
Artificial outcrops
107
To learn how to record outcrop data and make a map using artificial
outcrops outside or in the classroom.
Fold wavelength
111
To show the relationship between fold wave length and the
thickness of the strata.
Omission and repetition
116
To discover how the dip direction of the strata and the type of
fault determine whether omission or repetition of strata occur on
the surface and in boreholes.
Simple shear I
120
To show how beds change thickness when subjected to simple
shear.
Simple shear II
123
To show the effects of shearing on conglomerates.
Slip between beds during concentric folding
126
To determine which factors control the amount of slip during
concentric folding.
Squeezing plasticine
131
To determine how reduction spots and oolites change shape when
compressed.
Stress and strain
133
To show the relationship between stress and strain and the
strength of the rock.
Wavelength
137
To work out the relationship between wavelength, amplitude, dip of
limbs and crustal shortening.
18
Palaeontology
Ammonoid sutures
139
To explain why ammonites developed complex sutures.
Anterior margin
141
To determine the relationship between the sharpness of the
anterior/ventral fold, the area of the opening and the size of
sediment that could enter.
Crenulation
144
To determine the effect of crenulation on the strength of shells.
Crinoidal limestone
147
To see if there is any orientation to crinoid stems in a limestone.
The evolution of Micraster
148
To describe the changes between two species of Micraster.
Evolution using dice
150
To show how gradual change, preserving successful characteristics,
is much more likely than the chance creation of the complete cell.
Evolution using screws and nails
152
To allow students to make evolutionary trees from screws and nails
from five different time zones.
Extinction and continental drift
154
To determine the effect of continental collisions on the variety of
species.
Measuring bivalves
157
To make deductions about an assemblage of bivalves using
statistics.
Orientation of belemnites
159
To show the effect of water movement on the orientation of
belemnites.
Shaking shells
160
To determine which shells are the most resistant to attrition.
Shells as way-up indicators
162
To determine if loose valves can be used as way-up indicators in
sedimentary rocks.
Spines
165
To examine the advantages of lateral spines in preventing the
animal being turned over by predators or waves
19
Vertebrates
Human evolution
169
To determine some of the advantages in becoming bipedal.
Dinosaur footprints
174
To see what information can be deduced from dinosaur footprints.
Weighing a dinosaur.
176
To determine the weight of a dinosaur from a scaled replica.
Stratigraphy
Environmental interpretation of sands
178
To interpret the environment of formation of sands by matching
the characteristics of the sand to those of known environments.
Half lives
180
To show how the numbers of parent and daughter atoms change as
a radioactive element decays.
Economic Geology: Ore deposits and prospecting
Boreholes
182
To locate and describe a hidden oil trap from measurements made
on a model.
Gaps caused by normal faulting
185
To determine what factors control the size of the gap that
develops when a normal fault cuts different strata
Ore grade
188
To calculate the percentage of galena in a sample containing only
galena and calcite.
Placer deposits
190
To see how placer deposits are concentrated in different
environments.
Resistivity of rocks and minerals.
196
To determine the resistivity of rocks, and minerals and of
reservoir rocks, saturated with water, oil or gas. This can be used
as a revision exercise
20
Economic Geology: Construction and stability of the land
Angle of rest
198
To determine the angle of rest in loose sediments and the factors
which control it.
Landslides
202
To determine which factors are important in controlling the
occurrence of landslides.
Landslides and stress
207
To determine the effects of sediment size and overburden
pressure on landslides.
Roadstone
209
To determine which rocks are most suitable for wearing course
aggregate. Good for revision of rocks and minerals.
Strength of aggregate
211
To determine the resistance to impact of aggregate
Strength of Rocks I
215
To determine the relative strength of a variety of rocks. A good
way of becoming familiar with a range of common rocks.
Strength of rocks II
218
To determine what factors control the strength of rocks. Good for
revision of rocks and minerals.
Subsidence due to clay shrinkage
220
To determine the amount of subsidence likely to occur if the clay
dries out.
Subsidence due to mining
222
To determine the effect on the surface of underground mining.
Economic Geology: Energy
Hot rock
228
To determine the specific heat of a rock and thus how much heat
can be obtained from a given volume of rock.
Water
Porosity of sediment
233
Determining the porosity of sediment and the factors which
control it.
Dry porosity
236
Determining the porosity of sediment without soaking it.
Porosity of rocks
239
How to determine the porosity of rock samples.
21
Flow of oil and water
241
Experiments to determine the effect of grain size, sorting, length,
cross-section and temperature on the flow of fluids through
sediment.
Coefficient of permeability
246
To see how hydrostatic pressure effects water flow and to
calculate the co-efficient of permeability.
Darcy’s laws of permeability
249
To determine the relationship between the hydraulic gradient,
length of aquifer, cross sectional area and the volume of water
passing through.
Capillary movement
253
To show how water rises in sediments of different grain sizes.
Purifying water
256
To determine which sand is best for filtering water.
Contaminated aquifer
257
To see how difficult it is to remove a pollutant from an aquifer.
The rise and fall of the water table
259
To show the relationship between rainfall, height of water table
and porosity of the ground.
Earth
Earthquake
262
To determine the effects of crustal elasticity, fault surface
roughness, and confining pressure on displacement.
The effect of earthquakes on buildings
267
To explain why tall buildings are sometimes less damaged than
shorter ones.
The shadow zone
270
To discover which factors determine the start and end of the
shadow zone.
Isostasy
273
To determine the relationship between erosion and uplift of the
crust and deposition and depression of the crust.
22
The effects of isostasy
277
To show how isostasic adjustment affects the height and shape of
the land
Sea floor spreading
284
To work out what factors determine the amount of displacement of
the ridge along a transform fault.
Accretionary prism
287
To explain the sequence of strata found in an accretionary prism.
Other
Meteorite craters
289
To determine the effect of speed, size and density on the size of
the crater.
23
ATOMIC MASS AND DENSITY
Background information and purpose
Isomorphous minerals are those having the same molecular structure and
the same anions so the only variable is the cation. There should
therefore be a linear relationship between the atomic mass of the cation
and the density of the mineral. The purpose of this experiment is to test
this hypothesis.
Instructions
1 Choose one of the sets of minerals.
Set A, DE 1 to DE 4, are all carbonates:
Witherite is soluble in stomach acid and is thus poisonous. Don’t
lick your fingers. Wash your hands after the experiment.
DE1
DE2
DE3
DE4
Mineral
Aragonite
Strontianite
Witherite
Cerussite
Formula
CaCO3
SrCO3
BaCO3
PbCO3
atomic weight of cation
40.1
87.6
137.3
207.2
Set B, DE 5 to DE 7, are all sulphates:
DE5
DE6
DE7
DE8
Anhydrite
Celestite
Barite
Anglesite
CaSO4
SrSO4
BaSO4
PbSO4
40.4
87.6
137.3
207.2
2
Work out the density of each mineral by weighing first in air and then
in water. Density = weight in air
weight in air – weight in water
3
Plot your data and draw your conclusions
4
Repeat for the other set of minerals.
24
5 Repeat for DE 9 and DE 10 which are also carbonates. Plot them on
the same graph as the other carbonates.
DE9 Magnesite
DE10 Calcite
MgCO3
CaCO3
24.3
40.4
6 Repeat for DE 11 which is a sulphate and plot it on the same graph as
the other sulphates.
DE11 Gypsum
CaSO4 .2H20
40.4
7 What conclusions can you draw about DE9 to DE11.
Teacher’s Section
Requirements
Samples of all the minerals listed in the instructions. The samples should
be pure and at least 3cm long. All samples should have a nylon loop (made
from fishing line) attached with a small drop of araldite. All samples
should be numbered.
Beaker and balance.
Notes
This experiment does require quite careful measurements to get accurate
densities. The densities of the samples should be checked beforehand to
ensure that the samples have the correct density for that mineral. It is
possible to do this activity just using data from books, e.g. Rutley’s
Mineralogy
Results
The densities obtained should be similar to those given in text books e.g.
Rutley’s Mineralogy.
The minerals in each set should lie in a straight line because there is a
direct relationship between density and atomic weight of the cation.
Samples De9, 10 and 11 do not fit on the lines because they are not
isomorphous to either of the other groups.
Time
About one hour for all the samples.
Cost
£22 for all the minerals needed except Anglesite which is £10.
25
ALIGNMENT OF PHENOCRYSTS
Purpose
This experiment is designed to show you what causes phenocrysts to
become aligned. The syrup represents the magma and the sugar strands
the phenocrysts.
Instructions
Activity 1
1
Place the board on the wooden strip to give it a slope. Set up the
channel with the wooden gate at A, about 5cm from the end.
2
Pour about 600ml of golden syrup (about one large tin) into the area
behind the gate.
3
Sprinkle sugar strands onto the surface of the syrup.
4
Pull the gate away and carefully watch what happens to individual
strands.
5
Once the syrup is running down the trough look to see if there is any
preferred orientation of the strands. If possible take a vertical
photograph of the syrup.
Activity 2
1
Set up the channel and place the card against the channel entrance.
2
Pour one tin full of golden syrup into the magma chamber.
3
Sprinkle sugar strands on the syrup.
4
Remove the card and watch carefully the movement of individual
strands as they enter the channel, as they move along the channel
and as they leave it.
5
Note if there is any pattern to the orientation of the strands both in
the channel and at the end. Take a photograph if possible looking
straight down.
26
You should now have enough information to say what causes the
phenocrysts to become aligned and whether they will be parallel to or
at right angles to the direction of magma movement
Question
Would you expect the alignment of phenocrysts to be parallel to or
at right angles to the direction movement at the front of a lava flow?
Teacher’s Section
Requirements
Two 2lb tins of golden syrup to represent magma
One container of sugar strands to represent the phenocrysts
One channel and magma chamber made from wood ex 6cm (=5.5cm thick)
as shown in the diagram glued to plywood 34cm by 55cm. This will take
about 1 hour to make.
Support strip of wood 40cm by 5cm by 5cm
Gate block of wood 6cm by 4cm by 4cm
Piece of card 10cm by 7cm.
Camera
Notes
It is useful to take photographs of the patterns.
Beware things tend to get sticky. The syrup can be stored and reused.
The sugar strands float to the top and are best skimmed off and thrown
away. This experiment is best done as a demonstration. Students can then
plot rose diagrams from photocopies of the photographs.
Alternative methods
Peter York describes a method using wallpaper paste, pieces of plastic
and funnels to illustrate alignment of phenocrysts. Teaching Earth
Sciences 20 (4) 149.
Results
Students should find that the sugar strands are aligned parallel to the
direction of flow as they move into the channel from the magma chamber.
Once they are in the channel they move along without altering their
orientation except near the edges (remember how pooh sticks float down
a stream). As they leave the channel their orientation is again changed
so that it is at right angles to the direction of flow.
27
Time
30 minutes
Top board 2cm by 34cm by 5cm
Magma
chamber
magma chamber
Diameter 30cm
20 cm
Card placed here
15cm
Gap
4cm
Plywood
34 cm x 55cm
35 cm
4.5cm
A
channel sides
D
i
a
m wood 6cm thick
e
t
e
r
a
p
p
28
Apparatus for alignment of phenocrysts
29
COOLING AND CRYSTAL SIZE
Purpose
To show the relationship between speed of cooling and crystal size.
Activity
Draw up a table like this with three empty lines.
Temperature Time of
of slides
crystallisation
number of
centres
sizes of crystals
Average size
of crystals
1. Choose a pair of slides at room temperature.
2. Put one slide in the centre of the black piece of paper.
3. Use the glass rod to put a drop of salol on the slide and then
immediately put the other slide on top and squeeze it down.
4. Label the slide with the temperature and your initials.
5. Start the timer as soon as the first crystals appear.
6. Make a diagram to show where the crystals start to grow.
7. Watch the process of crystallisation and draw several diagrams to
illustrate the way the crystals grow and meet each other. Describe
the process of crystallisation. Turn the timer off when crystallisation
is complete.
8. Examine the slide and record the grain size of the ten largest crystals
or all if less than ten.
9. Repeat with the other pairs of slides. Try to make the size of the
drop of salol the same each time.
10. Plot the range of crystal sizes in each slide against temperature of
the slide.
30
Teacher’s Section
Requirements
Melted salol. ( phenyl salicyclic ) Do not over heat, Melt in a water bath at
60oC.
For each pair of students:
2 slides at room temperature
2 slides at 5oC ( use a fridge) or 0oC (use ice)
2 slides at 30oC use an oven or the top of a radiator
The slides should be 5cm by 5cm glass slides. Alternatively use petri
dishes or pieces of 2mm glass.
Timer
Glass rod
Pen for writing on glass
Hand lenses and grain size scale.
An A5 piece of black paper (makes the crystal growth easier to see)
Notes
This activity is best done if it is tied in with rock samples with different
grain sizes for instance samples taken across a dyke.
Speed of crystallisation is dependent on the size of the drop of salol so
as far as possible the drops should be the same size. It is also dependant
on the initial temperature of the salol.
If the room temperature slides take a long time to crystallise then omit
the warm slides. The salol on the cold slide may crystallise too quickly to
be timed and with too fine a grain to be measured.
The glass slides can be reused if washed in hot water. It is useful to keep
examples of slides which have crystallised well.
Time
30 minutes
Results
Crystallisation usually begins on the edges. The crystals grow as
expanding circles until they touch each other. The cooler slides
crystallise more rapidly. The crystals are often finer at the edges.
Cost
Salol £12 for 250g
31
COOLING IN A LIQUID
Purpose
To show how the temperature changes in the centre and edge of a cooling
and crystallising liquid.
Activity
1 Set up a table like this but with 60 lines:
time
Thermometer
comment
1
2
2 Set up the apparatus as shown in the diagram. Place the two
thermometers so that they are in the tin, one at the side and one
at the edge but not touching the tin. The clamps should hold the
thermometers high on the stem so that all temperatures less than
60o C can easily be seen.
3 Put lots of ice in the outside container but no water yet.
4 Record the temperature of the salol and then pour it into the tin.
5 Pour cold water into the outer container.
6 Start recording the temperature when the thermometers reach
their maximum. Record the temperature of both thermometers
every 60 seconds.
7 Observe and comment on the process of crystallisation. Record the
beginning of crystallisation and when it appears complete. Sketch the
solid when it has crystallised.
8 Carefully remove the thermometers by remelting the solid by
pouring hot water into the surrounding dish.
9 Plot your data and try to explain in detail the shapes of the cooling
curves.
32
Teacher’s Section
Requirements
2 thermometers
2 clamps and one retort stand
Tin about 8cm diameter and 3 cm deep
Salol ( phenyl salicyclate, enough to fill tin)
Container or tray 5cm deep
Ice
Timer
tray
Thermometers
supported by
retort stand
(not shown)
Inner Tin
Ice and water
salol
Notes
Care must be taken removing the clamps as it is easy to snap the ends off
the thermometers. Students should read up about crystallisation and
super cooling. A good reference is Advanced Chemistry by Philip
Mathews 1992 Cambridge.
Checks
Students may falsify their readings because they do not believe the
temperature can rise.
Results
The temperatures should drop quickly at the beginning and both
thermometers will cool at about the same speed because the liquid is
33
able to mix. The temperatures should then level out as crystallisation
begins because the latent heat of fusion is released. Once crystallisation
is complete the temperatures will again decrease but the outside one will
drop much faster than the central one because the latter is insulated and
the solid cannot mix. If the liquid supercools temperatures will increase
during crystallisation by up to 10oC.
Preparation
Determine the amount of salol needed and melt it in a waterbath at 60oC.
Time
60 minutes to record temperatures
Cost
Salol £12 for 250g
Cooling in a liquid
34
CRYSTALLISATION OF MIXTURES
Background.
By looking at thin sections of igneous rocks it is possible to determine
which mineral crystallised first. It would be reasonable to expect that
the mineral with highest melting temperature would always crystallise
first.
Purpose
To measure the temperature of crystallisation of salol and thymol both as
pure substances and as mixtures and to plot a phase diagram. This will
help to explain why the mineral with the highest temperature of
crystallisation does not always crystallise first.
Instructions
1. Set up a table like this with 60 lines.
time Thymol 100%
80%
60%
salol
0%
20%
40%
40%
60%
20%
80%
0%
100%
2. Take the test tube rack from the water bath.
3. Place thermometers in each boiling tube and start the timer.
4. Record the temperature of each thermometer every minute until
all tubes have crystallised, that is about 35minutes. Temperatures
will not always fall and may even go up briefly.
5. Underline each reading in blue when you first see crystals forming,
underline in red when the whole tube appears to have crystallised.
If the thermometer will lift the whole tube then it is solid
throughout. When the temperatures have dropped to about 30oC
place the rack in iced water to allow the rest to crystallise.
6. Plot temperature against time for each tube.
7. Plot temperature of crystallisation against composition and label
your phase diagram.
8. Draw your conclusions. Under what conditions does the mineral with
the lowest temperature of crystallisation crystallise first?
9. Replace the rack in the water bath so that the solid melts and the
thermometers can be removed. Wipe them with a dry paper towel.
35
Teacher’s Section
Requirements
6 thermometers
Six boiling tubes
There should be exactly the same amount ( 20ml or about 3cm depth)
of thymol/salol in each tube. The tubes should be filled beforehand
by a lab technician with Salol and thymol in the proportions given in
the table. The tubes should be labelled with the proportions. Any
labels on the tubes should be small and not block the view of that part
of the thermometer between 60oC and 15oC
Test tube rack
Water bath heated to 60oC
Timer
Container with iced water into which the rack will fit
Notes
It is often quite difficult to tell the temperature of crystallisation by
visual observation. The plateau on the graph should give it. Thymol often
supercools in which case it will come up to the crystallisation temperature
once it begins to crystallise. Students should be warned that the
temperature of some tubes may stop going down and may briefly increase
otherwise they falsify their readings. The 80% thymol / 20% salol tube
crystallises at below room temperature. That is why iced water is needed.
Results
The mixtures crystallise at a lower temperature than the pure substances
Time
About 50 minutes for setting up and taking readings.
Cost
Salol = phenyl salicyclate £12 for 250g
Thymol £13 for 100g
36
GRAVITY SETTLING
Purpose
To plot the speed of fall of olivine, augite and plagioclase in glycerol and
to calculate the speed of fall of crystals in basic and acid magma.
Background and data
Glycerol has a density of 1261 kg m-3 and a viscosity of 1.0kg s-1m-1 at 20oC
Use the following densities for the minerals and magma
For basic rocks
Olivine, 3500 kg m-3
augite 3400kg m-3
plagioclase (an) 2700kg m-3.
Basic magma at 1200oC 2600 kg m-3
For acid rocks
Plagioclase (ab) 2600kg m-3. orthoclase
quartz 2700kg m-3
2600kg m-3
Basic magma at 1200oC has a viscosity of 30kg s-1m-1
Acid magma at 1000oC has a viscosity of 1012kg s-1m-1 and a density of
2200kg m-3
Activity 1
1 Set up three tables like this each with 10 clear lines.
Mineral name
Distance of fall
Mineral density
Glycerol
Temperature density
Diameter mm
maximum
medium
minimum
viscosity
Average Type Time speed
diameter of
s
(v)
(d) mm fall
m s-1
2 Record the temperature of the glycerol
37
3 Choose a sample and if more than 5mm use the callipers to measure it.
If it is less than 5mm put it on the graph paper and estimate its size.
4 Hold it in the centre of the measuring cylinder, just above the glycerol
and let it fall. If it is a small crystal you may need to use the wire to prod
it through the capillary film to start its fall.
5 Start the timer as soon as the crystal reaches the top of the top
rubber band and stop it when it reaches the top of the lower band. Make
sure you have your eyes at the same level as the rubber band to avoid
parallax effects.
6 Repeat for several different sizes and for each of the minerals.
7 Record on the table above the type of fall.
sphere
End first
oblique
side first
8 Calculate the speed of fall in metres per second.
zigzag
9 Plot a graph of speed of fall (v) against the square of the average
diameter (d2).
Activity II Photomicrographs
Examine the photomicrographs and measure the diameter of the olivine
augite and plagioclase grains.
Activity III Calculations
The speed of fall is given by Stokes’ equation.
Velocity = (density of mineral – density of liquid) x g x d2
18 x Viscosity
g = 9.8m s-2. d = diameter of grain in metres. The densities are in
kg m-3 and the velocity in m s-1
Viscosity kg s-1m-1
38
Work out the speed of fall of grains in the photomicrographs. Adjust the
speed to take account of the different density and viscosity of the liquid,
magma not glycerol.
Now calculate the speed of fall of the minerals in an acid magma.
Minimum
2 cm
Glycerol
Elastic
band
30 cm
exactly
Minimum
2 cm
1 litre measuring
cylinder
Elastic
band
39
Teacher’s Section
Requirements
1 litre measuring cylinder
1.2 litres of glycerol
2 elastic bands to fit tightly around the measuring cylinder
Several (about 10) different sized crystals or pieces of the following
minerals: olivine, augite and plagioclase. These should range in
diameter from 10mm to 1mm.
Timer
Thermometer
Photomicrographs of olivine cumulate.
Small piece of Graph paper (normal with 1mm squares)
wire such as an unfolded paper clip
Tweezers
Callipers
Setting up
Pour the glycerol into the measuring cylinder. Pour it very slowly onto the
side of the measuring cylinder to avoid getting bubbles in the glycerol.
Place the top elastic band 2cm from the top of the glycerol and the lower
one exactly 30cm below that. Make sure the bands are horizontal all
around the cylinder. See diagram.
Notes
The experiment can be done by a student on his own or in pairs. Each pair
can do one mineral and then collect data from other pairs.
At the end drain as much glycerol out of the measuring cylinder as
possible. Then shake the minerals out onto tissue paper. The glycerol will
drain off over night. Typing the data into a spreadsheet and allowing it to
do all the calculating makes life easier.
Checks
Make sure the students lower themselves so that their eyes are level
with the elastic band when timing the fall. With the slower grains there is
a danger the students loose concentration and fail to notice when the
grain reaches the lower band.
Results
Students should note that it is difficult to measure the size of small
grains accurately. Stokes’ equation is for spheres and the grains are not
40
spheres. Useful class discussion can be had on the effect of this coupled
with the type of fall, or the speed of fall. The line on their graphs should
go through the origin.
Olivine crystals 1mm diameter should fall in glycerol at 20oC at about
1mm s-1. Because of the high viscosity and small difference in density
between minerals and magma the rate of fall is extremely small in acid
magmas, 10-7 cm per year.
Time
30 minutes for each mineral
Cost
Minerals 10 pieces each of augite, olivine and plagioclase £13
Glycerol £28 for 2.5 litres
Data on viscosity of magma from Hall, A 1987
Gravity settling
41
INVESTIGATING THE PROPERTIES OF IGNEOUS ROCKS
Purpose
To see if there is any relationship between density, grain size, and
percentage of dark minerals in igneous rocks.
Activity
1 Measure the density of each sample by weighing it in air and in water.
Density =
weight in air
weight in air - weight in water
2 Measure the grain size using the grain size card. If there is a
variation of grain size in the sample measure several grains and
take an average.
3 Estimate the percentage of dark minerals using the chart.
4 Tabulate your results and then plot the data on graphs.
5 Draw your conclusions.
Teacher’s Section
Requirements
A variety of named igneous rocks with loops made from nylon fishing line.
2 samples of acid, intermediate, basic, and ultrabasic rocks works
well. Samples should be about 5cm diameter.
Jar of water to immerse samples in
Spring balance or top pan balance
Grain size card, mineral percentage card
Time
About 1 hour for 8 rocks.
Results
Density and percentage of dark minerals should show a positive
relationship. Finer grained rocks look darker in hand specimens because
the dark shows through the white when they are thin. Grain size does not
affect density.
Costs
2 each of granite, diorite, gabbro and peridotite £20
42
MODAL ANALYSIS AND DENSITY
Purpose
To use point counting to work out the modal analysis and then to use this
information to calculate the density of the rock.
Instructions
Activity 1 Point Counting
1. Examine the rock and make sure you can distinguish the various
minerals. Devise a suitable one or two letter abbreviation for each
mineral.
2. Make a grid with 100 squares in it. It is easiest if you use a spread
sheet for this.
3. Place the ruler or strip of acetate on the rock near the top. Note the
mineral under the first centimetre line and write it in the first square
of your grid. Continue to note the mineral under each centimetre line
until you have reached the edge of the rock and then lower the ruler
by 1cm and start again. Continue until you have 100 readings by which
time your grid will be full.
Transparent ruler or acetate strip
4. Calculate the percentage of each mineral.
Activity 2 Working out the density of the minerals
1. Weigh samples of each mineral in air (Wa). Turn off the balance.
Rock slab
43
2. Place the beaker of water on the balance and then turn it on. Suspend
the mineral in the water and record the weight (Ww).
3. Calculate the density which will be Wa divided by Ww.
Activity 3 Calculating the density of the rock
1. To calculate the weight of 100 grams of the rock add together the
percentage of each mineral multiplied by its density. Divide the result
by 100 to get the rock’s density.
Activity 4 Checking the density of the rock
2. Take a sample of the rock and work out its density in the same way
that you worked out the density of the minerals.
44
Teacher’s Section
Requirements
Polished slab of rock about 15cm by 15cm. Any piece with about this area
will do. Pink granite is good because the minerals are easy to distinguish.
Rock slabs can usually be obtained free from stonemasons
A colour photo of the slab.
A piece of the same rock ideally about 4cm by 4cm by 4cm with a nylon
line glued to it
Transparent ruler or better a strip of clear acetate (cut from an
overhead transparency) marked every centimetre.
Samples of the minerals found in the rock in large enough samples to
weigh them. They should each have thin nylon (fishing) line glued to them
using araldite.
Balance.
Beaker large enough to take rock and mineral samples.
Notes
This method of calculating density is more accurate than using spring
balances but is still relatively inaccurate and it is unlikely that the results
of activities will be identical.
A pink granite is the best rock to work with; the minerals are distinct
and it is more interesting than gabbro. It is, however, informative to do
it for both gabbro and granite and compare the results.
The density of the minerals can of course be obtained from textbooks if
mineral samples are not available.
45
SPEED OF COOLING OF AN IGNEOUS BODY
Purpose
To determine what factors affect the speed of cooling of an igneous
body.
Instructions
Prior to the experiment
1 Select one of the following factors:
Size, Surface area, Shape/surface area, Composition, Grain size,
Density
2 Write an hypothesis about how you think cooling will be affected by
that variable and give a reason. Select the apparatus you will need and
say how you will use it. Decide how you will record the information.
Thermometers
Aluminium Shapes
or rock cubes
Insulation
Retort
stand and
Clamp
Bench
3 Weigh and measure the blocks or rock cubes
After the rocks and aluminium have been heated to just above 1000C
1 Place the retort stands and insulation ready on the table if needed.
46
2 Record the temperature of the oven. Start the timer immediately the
aluminium blocks or rock cubes are removed from the oven.
3 Place the blocks or cubes with the holes uppermost on the insulation on
the table supported if necessary by the retort stands.
4 Quickly place a drop of oil in each hole to ensure good thermal contact
with the thermometer.
5 Place a thermometer in each block or rock cube.
6 Record the temperature of every 2 minutes for 30 minutes.
7 Plot temperature against time for your blocks. The initial temperature
is the temperature of the oven.
8 Plot rate of cooling over the first 20 minutes against the factor you
have chosen.
Question
Give two reasons why a dolerite dyke intruded at 1100oC has a narrower
baked edge than a granite batholith intruded at 800oC.
Cylinders of different sizes
47
Teacher’s Section.
Requirements
For density, grain size and composition
Cubes of granite, basalt, dolerite, and gabbro 5cm by 5cm by 5cm. These
can be obtained from a stonemason at about £5 each. The holes, 7mm in
diameter, can be drilled with a concrete drilling bit but it would be
simpler though more expensive to get the stone masons to do it.
For size
Aluminium cylinders of various weights, say 40g, 120g, 250g, 500g
For shape
Aluminium cylinders of various shapes but all the same weight
Aluminium can be bought in various diameters. 250 g is a suitable
weight. Al has a density of 2.65 cm3 g-1 so you will need 94.3 cc for
each shape.
Aluminium cuboids of various shapes but all the same weight 250g is
suitable.
The rock cubes and aluminium blocks will need to be heated up to 110o C
all aluminium shapes should be drilled with a 7mm hole down to the centre.
The hole should be in the centre of the smallest face.
General
Thermometers, scales, timers, oven gloves, polystyrene tiles for
insulation, oil (3 in one or similar), retort stand and clamps.
oven.
Notes
Size/surface area is the best factor to test. Grain size and composition
do not effect the rate of cooling and involve a significant extra cost.
A much simpler experiment can be done using only aluminium cans and
boiling water, see Tuke. Earth Science: Activities and Demonstrations
Results
The larger the size the slower the cooling of similar shapes. Slabs and
rods cool quicker than cubes or squat cylinders. There is no detectable
difference in speed of cooling between any of the rock cubes.
48
Students will not have readings for the first couple of minutes while the
blocks are being removed from the oven and setup and only those
readings after the thermometers have reached maximum temperature
need be plotted. This should be explained in their write-up. Students
should explain that igneous rocks cool by conduction but in these
experiments convection of air and radiation are important.
The dyke has a much smaller mass and therefore much less thermal
energy and because it is sheet shaped cools more quickly.
Time
1 hour 10 minutes
Cost
Blocks of rock about £5.00 each from a stone masons, more if your have
them drilled
49
aluminium cylinders all the same weight
Rectangular aluminium shapes all the same weight
50
SPEED OF ERUPTION
Purpose
To calculate the speed of the vertical and lateral eruption blasts and of
the landslide as Mt. St. Helens erupted.
Instructions
1 Examine the photographs and put these events in order of occurrence:
vertical blast, landslide, lateral blast.
2 Make a tracing of the shape of the mountain from photo A using a hard
pencil or fine pen. It should be traced it on to the left hand side of a
piece of A5 paper in landscape arrangement.
3 Now trace the position of the landslide shown on photo B and beside
the line write the time. Now do the same for photos C, D, E and F.
Although much of the mountain is hidden in many of the photos the
tracing paper can always be lined correctly by using the kink in the profile
of the left side of the crater.
4 Make a table with these headings with 10 lines labelled B to J
Photo Time
Time
Distance
Distance
speed
speed
-1
seconds
interval
on map
on ground km s
Km h-1
seconds
cm
km
5 Plot a graph of the distance it has travelled against time. 3cm on the
photographs represents 1 km on the ground. Calculate the average speed.
6 Using the same technique calculate the average speed for the upward
blast and the lateral blast.
Teacher’s Section
Requirements
Photocopies of the photographs in Lipman and Mullineaux “ The 1980
eruption of Mt. St. Helens” One set per student with the photos lettered
from A to J. Each photo to be labelled with the time it was taken.
3 sheets of A5 tracing paper per student.
Hard sharp pencils
Time 1 hour
51
SPEED OF LAVA FLOWS
Purpose
Four short experiments to determine independently the effect of the
following variables on the speed of a lava flow: temperature, crystal
content, angle of slope, and volume..
Instructions
General
1. Mark A4 boards with lines going across 10cm from the top end and
then every 5cm.
2. Select slope and set up board on a tray on newspaper.
3. Stir syrup and record temperature.
4. Pour the syrup as shown in diagram onto the zero line.
5. Start the timer when the syrup reaches the 5cm line and record the
time it reaches the other lines.
spoon
spoon
15 cm
20 cm
A4 board
with
plastic
surface
10 cm
tray
5 cm
0 cm
Wooden
Block
For temperature
Select a medium slope board. Remove jug from water bath or from heater
and record the speed of flow for every 5oC drop in temperature.
52
For crystal content
Select a medium slope board. Use the syrup at 45oC and the sand at the
same temperature. Add 5ml sand and stir it in. Repeat adding 5ml sand
each time for four times.
For angle
Keep the syrup the same temperature but pour it onto 4 or 5 boards with
different angles.
For volume
Keep the same angle and temperature but use different sized spoons.
Plotting your data
Plot four separate graphs and on each plot the speed of flow (Y) against
each of the other variables (X) and draw your conclusions.
Question
Find out the viscosities of acid and basic magmas. Which type of lava will
flow fastest?
Boards and supports for lava flows
53
Teacher’s Section
Requirements
4 one pint jugs half full of Golden syrup heated to 65oC in a water bath
A4 boards preferably plastic covered, mine are made from old white
board. Draw lines across at 5cm intervals as on diagram.
timers, thermometers, permanent felt tip pen.
Trays large enough to take the boards.
50ml fine sand heated to 45oC.
Strips of wood to support the boards at angles varying from 1 to 12
degrees.
Desert spoons. 2 5ml tea spoons, 1 table spoon
Notes
Syrup heats up quicker and cools more quickly if kept in the tin
Things can get quite sticky so have some newspaper to put the boards on
and have some water and a cloth available. Clean the boards as soon as
they are finished with.
The syrup should be about 45oC for the sand to be added otherwise it
sinks too fast in the syrup.
Black treacle can be used, it has a more appropriate colour but requires a
higher temperature (70 degrees)
Movement is very slow below 35 degrees.
Spoons should be put in the syrup beforehand and kept there otherwise
they cool the syrup.
The syrup which has not had sand added can be reused.
When the flows are moving slowly it is possible for students to record
upto three flows at the same time using either 3 timers or noting the
clock time.
Glycerol can be used instead of syrup. Since its viscosity is known a much
more mathematical treatment can be made, see Teaching Earth Science
2004 vol 28(3) 26.
Results
The syrup flows faster if the: the temperature higher because of
reduced viscosity, the slope is steeper because of increase pull by
gravity, the volume greater because of the greater distance of the main
flow from the boundary layer. Sand slows the flow because of increased
friction. Basic lava and will therefore flow more quickly.
Time
Between 30 and 60 minutes for one variable.
54
STUDY OF A SLAB OF QUARTZ PORPHYRY
Purpose
To describe the size, composition and orientation of phenocrysts in a
porphyry. The percentage of phenocrysts tells us how much of the
magma had crystallised during the first period of cooling and the
orientation may tell us about its movement.
Instructions
1 Describe the quartz porphyry in as much detail as possible.
2 On your photocopies of the quartz porphyry slab draw lines parallel to
the one already printed every 2 cm.
3 Measure the length and breadth of each of the feldspar phenocrysts
(about 50 ). You should number each phenocryst as you measure it. For
those grains which are clearly elongate measure the angle that the long
axis of the phenocryst makes with line. The protractor should be on the
right side of the line and the angle should be measured clockwise from
the line to the phenocryst.
Marked line
Photocopy of
rock
Protractor
Phenocrysts
4 Determine the composition by point counting. Place your ruler on your
rock or photocopy and note the composition every 5mm, then move your
ruler down 5mm and repeat the process. The composition will be
feldspar (f), quartz (q), or matrix (m).
Make 100 readings and record your composition as a percentage.
55
5 Plot your results. Your composition should be plotted on either a bar
chart or a pie diagram, your angle of phenocrysts on a rose diagram, your
lengths and breadths on a scatter diagram. For your lengths and
breadths you should also give the maximum and minimum measured, and
average length.
Teacher’s Section
Requirements
A slab of quartz porphyry with feldspars large enough to be measured
and if possible showing some alignment. A line should be drawn parallel to
the long edge. A photocopy of the slab for each student.
30 cm clear rulers or better thin strips of acetate with marks every
5mm.
Protractors
Blank rose diagrams.
Notes
The purpose in numbering the phenocrysts is that it makes it much easier
to check on the accuracy of the work.
This activity can be followed by the experiment called “Alignment of
phenocrysts”
Time
30 minutes
56
THE POROSITY OF PUMICE
Purpose
To determine the porosity of pumice. To determine how much the volcanic
glass has been expanded by the exsolution of gas.
Instructions
Pumice is very porous but not permeable so indirect methods are needed
to determine its porosity.
1. Measure the density of the obsidian.
Weigh the obsidian (g).
Place a beaker under the spout of the displacement can. Fill up
the displacement can until it overflows. Empty the beaker and
replace it.
Then lower the obsidian slowly into the displacement can.
When it has stopped overflowing use the measuring cylinder to find
the volume of the water (ml) displaced. This is the volume of the
obsidian. The density is weight in air in grams / volume in ml
2. Measure the density of the pumice using the same method. If it
floats push it down with a thin piece of wire.
3. Calculate the volume occupied by one gram of obsidian. This is the
reciprocal of the density.
4. Calculate the volume occupied by one gram of pumice.
5. The amount of expansion =
volume of 1g of pumice
volume of 1g of obsidian
Consider the volume occupied by one gram of pumice. This consists of
volcanic glass and gas filled pore spaces. The volume occupied by the glass
will be the same as the volume occupied by 1g of obsidian. Therefore the
pore spaces will occupy the remainder. So the pore space in one gram of
pumice is the volume of 1g of pumice – volume of 1g of obsidian. The
porosity can now be calculated.
porosity of pumice = vol of 1g of pumice - vol of 1g of obsidian x100
as a percentage
vol of 1g pumice
Draw a column 1cm wide on graph paper to illustrate the volume of 1g of
obsidian and shade it. Beside it draw another column to illustrate the
volume of 1g of pumice, shade the volume occupied by the glass then the
unshaded part is the volume of the gas
57
Teacher’s Section
Requirements
Samples of pumice and obsidian, the larger the better, each with a nylon
loop attached with a small amount of araldite.
Balance
Beaker
Displacement can
Measuring cylinder
15cm piece of stiff wire
Notes
Students find it difficult to understand the reasoning behind calculating
the porosity. This experiment assumes that the obsidian and the glass in
the pumice have the same density.
Time
15 minutes for the measurements
58
VESICULAR BASALT
Purpose
To find the percentage of vesicles and thus the porosity in a slab of
vesicular basalt.
Instructions
1. Place a ruler on the photocopy and note whether it is rock or
vesicle beneath the 1cm line. Repeat for every centimetre line along
the ruler where it is over the rock.
transparent
ruler
Basalt
Vesicles filled
with polyfiller
2. Move the ruler down and repeat until you have 100 readings.
3. Calculate the percentage of rock and of vesicles.
4. Work out how much the magma was enlarged by the presence of
the vesicles.
5. If the vesicles are large enough measure the diameter of fifty.
6. Calculate the mean size and the range.
7. Plot a bar graph of the size distribution.
59
Teacher’s Section
Requirements
A piece of vesicular basalt with a sawn face. The size depends on the size
of the vesicles. Fill in the holes with Polyfiller. Place a scale on the edge
of the slab and photocopy enlarging if necessary (see appendix 7).
Notes
At the top of a lava flow there may a gradation in the size of the vesicles
and this change could then be studied.
Time
30 minutes
60
ANDALUSITE SLATE
Purpose
To see if there is any preferred orientation to andalusite crystals in
andalusite slate.
Activity
1. On the photocopy of the cleavage surface measure the angle of the
crystals to the marked line. Use the protractor with the curved side
on the right so that you only record angles between 0o and 180o.
Make at least 20 measurements and number each crystal as you
measure it.
2. Now record the angle of crystals exposed on one of the edges in a
vertical plane. Hold the protractor with the 0o –180o line parallel to
the cleavage and record the angle of as many crystals as you can.
3. Repeat activity 3 on the edge at right angles to the last one.
4. Plot as three separate rose
diagrams.
Cleavage surface
Sawn surface
Slab of andalusite slate cut at right angles to cleavage surface. The faces
are then photocopied
61
Teacher’s Section
Requirements
Photocopies of a piece of andalusite slate, about 10cm by 30cm by 30cm
with a line drawn on the cleavage face. Two edges should be cut at right
angles and these also photocopied. See appendix 7 for photocopying
rocks.
Protractors
Blank rose diagrams.
Notes
A good source of slabs is along the path in Glenderaterra Beck near
Keswick.
Checks
Make sure the students keep the protractor parallel with the line or the
cleavage.
Results
There should be no preferred orientation.
Time
30 minutes for making the three sets of readings.
62
METAMORPHIC AUREOLE
Purpose
To show how the temperature changes in the rocks adjacent to an
intrusion as the intrusion cools.
Activity
The sand represents the country rock and the hot water the intrusion.
1
Place four thermometers in the sand as shown in the diagram. Each
thermometer should be placed so that the bulb is about 5cm below
the surface.
2
Make up a chart like this but with at least 30 lines, to record the
temperature shown by each thermometer.
time
temperature
of water
temperature of sand
1
2
3
4
3
Record the temperature shown by all the thermometers before
pouring in the water.
4
Pour boiling water into the small tin and quickly put on the lid.
Place the fifth thermometer in the hole in the tin lid so that the
bulb is 5cm below the lid.
5
Start your timer and start recording the temperature shown by
each thermometer every two minutes until all thermometers show a
decrease in temperature.
6
Plot all the temperatures on a single piece of graph paper. Use the
graph paper in landscape format and plot temperature on the
vertical axis 1cm = 5 degrees and time 1cm = 4 minutes on the
horizontal axis.
63
7
Collect the data of tin diameter the inner tin, damp or dry sand,
and time to maximum temperature for each thermometer from
other students in a table like the one below.
Time to maximum temperature
name
Diam
eter
dry
or
damp
Thermometer
1
Time
2
temp
time
3
temp
Time
4
temp
time
8
For tins with dry sand plot size of the inner tin against time to
maximum temperature. For two tins of equal diameter but one with
damp sand and one with dry sand plot the time to maximum
temperature.
9
Answer the questions below.
a) How does the temperature change with distance away from the
intrusion?
b) How does the size of the intrusion affect the size of the
metamorphic aureole?
c) How does the size of the intrusion affect the thermal
gradient?
d) How does the temperature at any one place change with time?
e) Which will cool fastest a large or a small intrusion?
f) Does damp rock transmit heat energy more of less quickly than
dry rock?
64
temp
Metamorphic aureole
Inner
tin
Sand
2½ cm
Outer
tin
1½ cm
Water
3½ cm
½ cm
Plan View
Thermometers
Rubber
square
Inner
tin
Hot
Water
Outer
tin
Sand
Polystyrene tile
Side View
65
Teacher’s Section
Requirements
Round tins about 24cm diameter and 11 cm deep, Roses Chocolates tins are
ideal. Alternatively a cake tin can be bought from a hardware store.
A variety of smaller tins about the same height but varying in diameter
from 78 to 110 mm (see notes).
Sand
5 thermometers
Polystyrene tiles at least 25cm across
Timer
Kettles to boil enough water
Making the apparatus (About 1 hour for 5 tins)
Cut the tile to the size of the large tin and place it in the bottom. Place
the smaller tin in the centre on top of the tile and fill the space between
them with well compacted dry or damp sand. The thermometers should
have small pieces of rubber or plastic collars on them to show what depth
they should be inserted into the sand or water. Make a hole just large
enough to take a thermometer in the centre of the lid of the smaller tin.
Notes
To show the variation of temperature away from an intrusion and with
time you need only one outer and one inner tin but having the results from
a variety of sizes of inner tins allows students to answer more questions.
These are the sizes of tins I have used but smaller ones might be better
as they would reach maximum temperature more quickly
Results
The sand farthest away takes longer to reach maximum temperature.
The maximum temperature reached decreases away from the inner tin.
The innermost thermometer shows a very rapid rise in temperature and a
slow decline. Other thermometers show a gentler rise in temperature.
The larger the inner tin the longer the cooling takes. Wet sand cools
faster than dry sand.
Time
Readings need to be taken until all the thermometers begin to show a
decrease in temperature. All the thermometers in a damp 78mm tin will
cool with an hour. A 90mm diameter tin will take 100minutes but the
change in temperature is very slow below 60o.
66
Tin for metamorphic aureole
67
DESERT SAND
Purpose
To explain why sand grains that have been transported by wind are
generally better rounded than those transported by water.
Instructions
1. Choose four pieces of broken brick or limestone and sketch one piece.
2. Weigh them and use the roundness chart to give them a roundness
value.
3. Place them in an empty container and screw on the lid firmly.
4. Shake vigorously for five minutes.
5. Remove the four largest pieces and sketch one of them and give it a
roundness value.
6. Weigh only the four largest pieces.
7. Now repeat instructions 1 to 5 but put the four new pieces into the
empty container and fill it with water. Shake with the same vigour as
before.
8. Allow the pieces to dry overnight and then weigh them and sketch
them and give them a roundness value.
9. Describe and explain your results
68
Teacher’s Section
Requirements
Two plastic containers with screw lids which do not leak water
8 pieces of broken brick or limestone about 2cm diameter
Timer
Balance
Roundness chart
Notes
There is often some water leakage so if possible do the latter part of the
experiment over a sink or over newspaper.
Check that the students shake for the full five minutes and with equal
vigour for each container.
To make the experiment more rigorous use a lap counter to count the
shakes on the dry run and then do the same number at the same speed
on the wet run.
Results
Those shaken in water should be significantly less rounded than those
shaken in air.
Time
Total about 30 minutes but samples need to dry overnight.
69
FALLING GRAINS
Purpose
To determine the effect of size, density, roundness and sphericity on the
speed of fall of grains in water. This information can help explain some of
the thin layers of different types of grains in sedimentary rocks.
Instructions
Set up the apparatus as shown in the diagram.
Activity I Size
1. Select several balls of different sizes but all made of the same
material.
2. Drop one of them from as close as possible to the water surface.
3. Start the timer as the ball passes the top elastic band. Look
directly at the band, to avoid any parallax effects
4. Stop the timer as it passes the lower band.
5. Repeat with all the other grains you have chosen.
6. Calculate the speed of fall for each size and plot your results.
For each of the activities II to IV follow instructions for Activity I.
Activity II Density
1. Select a steel (density 7.7g per cc), glass (2.6g per cc) and Fimo
(1.9 g per cc) ball all the same size. Plot density against speed of
fall.
Activity III Roundness
1. Take fimo shapes of different roundness but the same size.
Measure the roundness of each using a roundness chart. Does
roundness have any effect on speed of fall?
Activity IV Sphericity
Choose a variety of Fimo shapes with different sphericities but the same
volume. Give names to the various shapes. Note the way they fall through
the water.
70
Activity V Samples
Examine the sample of micaceous sandstone and explain why the mica
forms separate layers.
Examine the sample of graded bedding and say which side was the original
top and why.
Top of
Water
Water
3 cm
Plastic Tube
5 cm diameter
2 m long
Bench
150 cm
Wire
Elastic
bands
G
Clamp
Bucket
Bung
71
Teacher’s Section
Requirements
Steel balls of the following sizes: 3, 4 and 5mm A variety of sizes can be
bought from bike shops
Glass balls of the following sizes: 3, 5, 7, 10mm (marbles)
Fimo balls of the following sizes: 5, 10mm
Fimo balls all the same weight but different degrees of roundness
Fimo shapes all the same weight but a variety of shapes e.g. sphere, cube,
prolate spheroid, oblate spheroid, disc, roller, blade.
2m long clear rigid plastic tube 5cm internal diameter and a wall thickness
of 3mm. It should be sealed at the lower end with a bung.
Suitable support for the tube (G clamp onto table and wire)
Roundness chart
Timer
2 elastic bands to fit around tube
Bucket (optional)
Making the Fimo balls (15 minutes)
Fimo can be bought in a variety of colours in any modelling or toy shop.
Make one ball of the correct size, weigh it, then cut other pieces of that
weight and shape them. Heat them in an oven to make them hard. All Fimo
shapes of the same weight should be made from the same colour of Fimo.
Setting up the tube
Place the tube in a bucket, support the tube vertically and fill it with
water to within 2cm of the top. Place elastic bands on the tube 5cm
below the top of the water and a second band 150cm below the top one.
Notes
If the end of the tube is placed in a bucket then if the seal does break
the water will all be caught in the bucket. The lower elastic band should
be above the bucket, at a height so that it can be easily read by students.
Check that students are looking directly across the tube and elastic band,
especially with the lower one when recording the time. Steel balls larger
than 6mm fall too quickly to measure.
Results
Speed increases with increasing size, density, roundness and sphericity
Cost
Plastic tube £22 (look in yellow pages under plastic engineering materials)
72
FLOCCULATION
Background
Estuaries are full of mud because as the river water mixes with seawater
the clay comes out of suspension and sinks to the bottom. This process is
called flocculation.
Activity I
Purpose
To determine what chemicals in seawater cause the clay to flocculate.
This will be done by mixing each of the main chemicals found in sea water
with muddy water.
1. Mark each boiling tube at the 20ml level.
2. Fill each tube with 20ml of well-stirred muddy water.
3. Label each tube with the formula for one of the solutions and also
ones for distilled water and for seawater.
4. Fill and label each measuring cylinder with 20ml of solution
5. Add 20ml of each solution to the appropriate tube.
6. Put corks in and shake each tube and start the timer.
7. Record the depth of clear water in each tube every half-hour for
two hours. Look again after 24 hours.
8. Draw your conclusions.
Activity II
To determine what effect different concentrations of sodium chloride
solution have on the rate of flocculation.
Follow the instructions for activity I but use the NaCl solutions instead
and take your readings every 10 minutes for one hour.
73
meniscus
Clear
Water
Depth of
Clear
Water
Boiling tube
Muddy
Water
Question
Why are estuaries so muddy?
74
Teacher’s Section
Requirements
Muddy water. This is best made by adding cat litter to distilled water,
about 50ml cat litter to 1 litre distilled water, let it settle for one hour
and then keep the top 500ml.
Distilled water
Boiling tubes with corks and stand
Measuring cylinders 20ml or 50ml
1 timer for each activity
Labels for boiling tubes
Activity 1
The following solutions. 20 ml is needed for each pair of students.
Salt
grams per litre
Sodium chloride
27.3
Magnesium chloride
3.2
Magnesium sulphate
2.3
Calcium sulphate
1.2
Potassium chloride
0.7
Calcium carbonate
0.1
Sea, river, rain water as interesting comparisons
Activity II
Solutions of Sodium chloride. 20 ml is needed per pair of students.
1g, 2g, 5g, 10g, 20g, 30g per litre
Notes
It is important to make sure the clay suspension is well stirred.
The boundary between the clear water and the water with the
flocculated clay is distinct and sharp.
Checks
Make sure students stir the muddy water before adding it to the tubes
and that they shake the tubes after the solutions have been added. Also
check that they put the right solution into the labelled tube.
Results
MgCl2 causes the fastest flocculation, then seawater, then NaCl, then
MgSO4 and CaSO4. KCl has a slight effect and CaCO3 has no effect,
neither does distilled water.
Initially the stronger the concentration of NaCl the faster the clay
flocculates but the weaker solutions have caught up after one hour.
75
Estuaries are muddy because this is where muddy fresh water mixes with
salt water.
Time
Activity I. Initially about 20 minutes and then 5 minutes every half-hour.
Clear results can be seen after one hour.
Activity II 1 hour. Both activities can be done at the same time.
76
MOVEMENT OF GRAINS
Purpose
Three experiments to determine the effect of shape, size, and bed
roughness on the movement of grains.
General instructions
Place the grains 10cm from the top of the trough.
Place the tray under the top of the trough to catch splashes.
Place the container below the end of the trough to catch the grains.
Pour a jug of water quickly down the trough.
Observe and record how the grains move.
Measure how far the different shapes have moved.
Repeat so that you have 3 sets of results.
Activity I Shape
Select grains of different shapes but one colour (all grains of the same
colour have the same weight).
Activity II Size
Select grains of different sizes but the same shape.
Activity III Bed roughness
Select grains of the same shape but different sizes.
Repeat with different beds
Stop
End
Pour water here
Put
Put grains
Grains
here
Here
Block
of
Wood
Tray
Sand or pebbles
Sand or
stuck to bottom
Pebbles
Sandtoor
Stuck
pebbles
Bottom
glued to
bottom
Flat bottomed
guttering
Bench
Block of wood
Sink
Box to catch
Boxgrains
to
Catch
Grains
77
Teacher’s Section
Requirements
Fimo shapes of different shapes and sizes. At least 30 pieces are needed.
Fimo should be cut into pieces with the following weights: 2g, 3g,
6g. The different weights should be made from different coloured
Fimo. The pieces of Fimo should then be moulded into the following
shapes: cubes, spheres, discs, cylinders, pyramids and then heated.
Tape measure.
Clinometer to measure the slope.
Blocks of wood 10cm high to support the guttering.
2 litre jug.
3 one metre lengths of flat bottomed guttering each fitted with a stop
end and each with sand or gravel grains of different sizes glued to the
bottom.
Container to catch grains e.g. ice cream box. Tray ( 30cm by 40cm) to
catch splashes
Making the equipment (30 minutes for 3 pieces of guttering)
Cut the guttering into 1m lengths and fit the stop ends. Cover the bottom
with Unibond adhesive and then cover it with plenty of sand or gravel.
Press the sediment into the glue and remove the loose pieces when the
glue has dried. Suitable sizes are 16mm, 8mm, 4mm
Notes and results
Needs to be done next to a sink. This practical is good for designing,
discussing and evaluating but the results are not repeatable.
Generally spheres travel fastest and by rolling. Cubes may roll or slide.
Cylinders roll but end up caught on the side. Discs usually slide but
sometimes flip. Pyramids roll or slide. The speeds and distances are very
variable. Students should note in their evaluation that the water flow is
not like a stream. It would be better to have a continuous flow of water
but that would require a biggish pump.
Time
15 minutes for each activity
Cost
Guttering £8 for 2m
78
trough for movement of grains
79
SCREE SLOPES
Purpose
To determine how size, shape and height of fall affect the distance a
particle moves down a scree slope.
In this experiment the scree slope is represented by the curved sloping
board covered with pebbles and the cliff by a wooden block which can be
raised.
Instructions
Activity I Effect of size
1. Record the size of the grains on the scree slopes
2. Choose a pebble and record its letter and intermediate diameter.
3. Adjust and record the height of the cliff. Start with it at 0
4. Place the pebble on the top and then slowly and gently push it off.
5. Record the position it comes to rest (if it rolls off the side start
again).
6. Repeat with the same pebble until you get three readings and then
average them.
7. Repeat with pebbles of different sizes and with the cliff at different
heights
8. Repeat instructions 1 to 7 with a different board.
9. For each board plot your average distances against grain size and
distance against height of fall. Draw your conclusions.
Activity II Effect of shape
1. Repeat instructions 1 to 9 using the Fimo shapes using first the
smaller size and then the larger size.
Activity III
Examine the photographs. Are the large boulders at the top or bottom of
the scree slope?
80
Teacher’s Section
Requirements
2 Plywood boards 60cm by 30cm supported as shown in diagram.
Angular pebbles labelled A to G with the following intermediate
diameters
A 10mm, B 15mm, C 20mm, D 25mm, E 35mm, F 45mm
Fimo shapes: a disc, sphere, roller and cube each weighing 2.0g and a
second set each weighting 3.0g. (see page 75)
Tape measure (cloth one is best)
Photographs of scree slopes
Making the equipment (2 hours per slope)
Follow the diagram to make the board. The plywood boards should have
angular pebbles glued on to them using Unibond or a similar glue. Spread
glue thickly over the board and then cover it with pebbles. One board
should have pebbles 2 to 4cm and the other 1 to 2cm. The board should
have the same curvature as shown in the diagram so that it mimics the
curve of actual scree slopes.
Notes
As there is a wide variation in the distance travelled by any one pebble it
might be better to take an average of more than three readings. It is
useful to use some statistics to see if the conclusions are valid.
Results
The distance travelled increases with the size of pebble but surprisingly
the height of fall makes little difference. Spheres travel furthest, then
cubes, then discs and rollers travel the least distance.
Time
About 40 minutes for each board for Activity I and the same for Activity
II. Activity III 5 minutes
81
Scree slopes
Adjustable
Platform
Scale in cm
Maximum
angle = 35°
30
cm
91 cm long slope
Hardboard with angular grains
glued to surface
28.5 cm
Wooden
Supports
Bolt with
wing nut
Board 85cm long x 30
cm wide x 2 cm thick
Slot in wood so it
can be raised and
lowered
82
Rear view showing mechanism for changing height of cliff
View of scree slope
83
SPEED OF TURBIDITY CURRENTS
Purpose
To see how density, volume, and temperature affect the speed of
turbidity currents.
Instructions
Activity I Density
1. Draw up a table to record the following information: salt mixture,
density, time to reach 50cm, 100cm and 150cm.
2. Choose the least dense solution and measure its density using the
hydrometer.
3. Pour 200ml of the solution quickly into the trough and start the timer
as soon as it reaches the bottom.
4. Record the time at which it reaches the 50cm, 100cm and 150cm
marks.
5. Stir the water and allow it to become still.
6. Repeat twice with the same solution. Pour it at the same rate and from
exactly the same position.
7. Repeat instructions 2 to 5 with each of the other solutions in order of
increasing concentration.
8. Plot your results and draw your conclusions.
Activity II Volume
Repeat the instructions for Activity I except that in this case you will
vary the volume. Use the ¼ concentration salt solution and use first
100ml then 200ml, then 300ml and lastly 400ml.
Activity III Temperature
Follow the instructions broadly for Activity I but use the room
temperature and cold solutions
84
Take 200ml of the room temperature solution, measure its temperature
and pour it into the tank then measure the temperature of the cold
solution and pour 200ml of it into the tank.
Round
Guttering
Glass Tank
Water
150cm
100cm
50cm
0cm
85
Teacher’s Section
Requirements
1. Long glass tank about 200cm by 10cm by 10cm marked at 50cm,
100cm, and 150cm from bottom end of guttering (see appendix).
2. Section of round guttering cut obliquely at the end so that it fits
against the floor of the tank.
3. 100ml and 200ml and 400ml beakers.
4. The following four salt solutions: ¼, ½, ¾ maximum concentration and
maximum concentration. Maximum concentration is 330g per litre. All
solutions should be tinted with food colouring. More of the ¼ solution
is needed than of the others.
5. ¼ Maximum solution one at about 0oC.
6. Hydrometer suitable for measuring 1.0 to 1.25 g per cc
Notes
Students need to work in pairs.
The tank needs to be emptied and the water replaced after each pair of
students and the problem of the changing composition of the tank water
should be commented on by the students in their evaluation. Slope is
another important control but it is difficult to demonstrate without a
deep tank.
A saturated solution of NaCl is easily made up and kept and can then be
diluted as required.
Results
Increased density caused by more salt or lower temperature increases
speed because a denser liquid has a greater kinetic energy. Increased
volume also increases speed.
Cost
Tank, £25 if made, see appendix; £40 if bought
86
TRANSPORT BY WIND
Purpose
To explain how size, shape and density affect the ease with which grains
can be moved by wind:
Instructions
In each activity the grains should be poured carefully and slowly from the
appropriate container just in front of and above the nozzle of the hair
dryer as in the diagram.
Activity I
Take the container of poorly sorted grains (200ml 0.125 to 4mm) and
pour them out very slowly by shaking the container in front of the
hairdryer.
Hair dryer
Plastic cup
of sand
Plastic
Cup of
Sand
Wooden support
Wooden
Support
Sheet
Sheetof
ofclear
plastic
plasti
Plastic
Small card
Small
boxes
Card
Boxes
Note the distribution of grains in the trays.
Use the grain size card to measure the maximum and average grain size in
each tray.
Plot average grain size against distance from hairdryer.
87
Activity II
Take the 0.1 g grains of quartz and mica and pour them in front of the
hair drier.
Note how far from the hair drier each grain lands.
Plot a graph of number and type of grain against distance.
Repeat using the 0.2g grains.
Activity III
Take the galena and pour it in front of the hair drier. Measure the volume
in each box. Tip it all back into the original container.
Repeat with the sand.
Plot a bar graph of volume against distance for each.
Question
At Kalgoolie, in Australia, small grains of gold are found mixed in which
larger grains of quartz sand in the wind blown sediment close to the
outcrop of the gold vein. Explain why.
Apparatus for transport by wind
88
Teacher’s Section
Requirements
200ml poorly sorted sand, 0.125 to 4mm.
10 grains of quartz and 10 grains of mica each weighing 0.1g.
As above but each weighting 0.2g.
100ml of galena and 100ml of quartz sand all with a grain size of 0.5mm.
Grain size scale.
Hairdryer.
100ml measuring cylinder and funnel.
8 cardboard boxes 7.5 by 10cm labelled A to H.
Apparatus as shown in diagram.
Making the apparatus (80 minutes )
You will need a base board 10.5cm wide and 85cm long and 12mm thick.
The front is perspex and is 17cm by 67cm and the back is hardboard of
the same size. The ends are 16cm by 10.5cm by 1.2mm. One end has a U
shaped notch to take the hair drier nozzle. There will also need to be
support for the body of the hair drier. Assemble as in diagram.
Notes and results
The maximum grain size decreases with distance but all trays contain the
finer grain sizes. Students usually do not note this. The mica, because of
its shape is carried much further than the quartz, sometimes beyond the
boxes.
The galena all ends up close to the hairdryer.
The wind was unable to carry the dense gold grains or the large quartz
grains far.
Time
15 minutes
Cost
Hairdryer £6
89
COMPACTION
Purpose
To determine the amount of compaction shown by sediment of different
sizes. Compaction is important when building roads and houses on loose
materials and when explaining sediment changes on deltas.
Instructions
Activity I The effect of vibrations
1. Choose one of the sediments and an empty beaker.
2. Pour the sediment slowly into the beaker until you have about
500ml. Make the top as level as possible using the spatula. Do not
shake the beaker.
3. Record the height of the sediment.
4. Now thump the top of the table with your fist five times.
5. Record the new height of the sediment.
6. Pour the sediment back into the original container.
7. Repeat with other grain sizes making sure you thump the table with
the same number and strength of blows as before.
Activity III The effect of pressure
1. Pour the sediment into the beaker and level it and record its
height.
2. Put the wooden disc into the beaker and place a 1 kg weight on the
disc.
3. Record the height of the sediment.
4. Repeat with a 2 kg weight.
5. Now tap the bench as before and record the height.
6. Remove the weights and disc and pour the sand back.
90
Teacher’s Section
Requirements
500ml beakers with a scale stuck to each to record height.
Well sorted sand and gravel of a range of sizes 0.25mm, 0.5mm, 1.0mm,
2mm, 4mm are suitable. About 500ml of each should be put in a jar.
Disc or jam jar top to fit into beaker
1 and 2 kg weights
Notes
Each pair of students should take one sediment and work through the
activities. All students should then compare results at the end.
Students should work on separate benches.
Checks
Beware of students shaking the beaker to level the sediment.
Make sure the students tap the table in the same way each time.
Results
Grain sizes ¼ to 2mm compact by about 5%, larger grains compact less.
Adding the weight does not compact the sediments and largely prevents
tapping having any effect.
Time
30 minutes
91
PURITY OF LIMESTONES
Purpose
To determine whether there is a relationship between the colour of a
limestone and the amount of impurities it contains.
Limestone has more uses than any other rock and for many of those uses
(cement, toothpaste) it is important to know the purity.
(This experiment will only catch those impurities which are insoluble in
2M HCl. Other carbonates and some sulphides and oxides will be
dissolved.)
Instructions
1
Take one bag of limestone chips and remove the large piece of
limestone. Note its number and match its colour against the rock
colour chart if there is one.
2
Weigh out accurately a quantity of limestone, about 10 grams.
3
Write your name and sample number on the beaker.
4
Place the chips in the beaker and add 50ml of acid.
5
Write your name and sample number on the edge of the filter paper
and weigh it.
6
When the sample has stopped fizzing add a further 20ml of acid. If
no further fizzing occurs then the CaCO3 has all been dissolved.
7
Now filter the contents of the beaker and carefully wash all the
contents on to the filter paper.
8
Once all the water has passed through the filter paper carefully take
it out of the funnel, fold it so no sediment can escape and place it to
dry.
9
When it has dried weigh the filter paper again and calculate the
percentage of impurities.
Weight of paper + solids – weight of paper x100
Weight of limestone
10
Compare your results with other members of the class and draw your
conclusions.
92
Teacher’s Section
Requirements
You will need a variety of limestones of different colours: white, cream
and several shades of grey. You should have one large piece say 5cm by
5cm plus several small chips.
A 100ml beaker and small funnel, retort stand to hold funnel, filter paper,
wash bottle of distilled water, 2 molar hydrochloric acid.
Access to balance which will measure to 0.1g.
Oven (optional).
Rock colour chart (optional).
Notes
The limestones can be chipped in a crusher or by hammering them inside a
piece of cloth.
If you do not have a rock colour chart then a paint colour chart will do, or
else put them in order of increasing darkness.
Filter papers are best dried in an oven, but can be dried on a radiator or
window sill.
Results
Generally the darker the limestone the more impure it is.
Time
30 minutes.
93
THE SHAPE OF PEBBLES
Purpose
To see if the shape of a set of pebbles is controlled by the bedding
planes.
Background information
When a rock breaks the fractures will be controlled by any planes of
weakness, e.g. bedding planes, joints or cleavage.
The axes of a pebble are named as follows: Long axis = A
Intermediate axis = B
Short axis = C
The planes containing those axes are referred to as the AB plane, AC
plane and the BC plane.
A axis
C axis
B axis
Instructions
1 Copy this table but with 25 rows.
Number
Bedding
parallel
to
of
AB plane
BC plane
pebble
AC plane
No plane
2 Choose a pebble and examine it. Note if the bedding plane is parallel to
any of the planes.
3 Put a tick in the appropriate box in the table.
4 Total up the ticks in each column and draw your conclusions.
94
Teacher’s Section
Requirements
A minimum of 25 (100 would be good number) pebbles all from the same
locality and of the same lithology with some signs of bedding in each.
Pebbles from the Budleigh Salterton pebble bed are suitable, many other
well indurated rock types are suitable.
1 pebble with bedding parallel to plane of largest cross section area.
Notes
It is important that students understand and can locate the axes and
planes on a rounded pebble. Use the pebble with the bedding parallel to
the AB planes as an example. A trial run is useful. 25 pebbles is enough
for one student. It is good if students combine their results and so have
larger sample from which to draw their conclusions.
Results
Most bedding planes in the Budleigh Salterton pebbles are not parallel to
any plane so the original rock was already well cemented before any joints
formed and before the rock was eroded and turned to pebbles.
Time
45 minutes including time to understand the system of naming the planes
and a trial run of 5 samples.
95
THE SIZES OF PEBBLES
Purpose
To determine how the sizes of pebbles seen on a flat surface relate to
the sizes of the actual pebbles. To devise a method which will give an
accurate idea of the real maximum pebble size when looking at a flat
surface of a conglomerate or breccia.
1. Imagine a rock containing spherical pebbles all 5cm in diameter. If
the rock is now sliced what will the sizes of the pebbles shown on the
surface be? What will be the maximum size and minimum size?
Because the pebbles are randomly distributed some pebbles will be
sliced through their maximum diameters whereas others will just have
a slice taken off the edge. We can get an idea of the range of sizes on
the face by slicing a sphere and measuring the apparent diameters.
Activity I Apple
1. Measure the “equatorial” diameter of your apple.
Slice apple and
measure maximum
diameter of each
slice.
2. Slice your apple into 1cm thick slices. Your slices should go northsouth. Measure the maximum diameter of each slice in the plane of
the “equator”. Slice your apple on the wooden board or tray.
96
3. Calculate the diameter of each slice as a percentage of the
diameter of the apple.
4. Work out a) the average length as a percentage.
b) the fraction of lengths greater than 90% of the maximum
5. Eat your apple.
Activity II Paper
1. Draw a circle 20cm in diameter on lined paper. This represents a
pebble.
2. Each line represents where the pebble might be sliced. Measure
the diameters of the pebble along each line.
3. Collect data from the other students and plot a frequency graph of
percentages using a 5% interval.
4. Calculate the average size and what fraction that is of the
maximum
Activity III Slice of conglomerate
1. Measure the sizes of the pebbles on the surface of the slice.
2. Calculate the average size.
3. Use the information you found in Activity II to calculate the actual
average size of the pebbles (if you could measure them in 3
dimensions).
4. If the conglomerate is well sorted how close is the maximum size
you have measured on the surface to the real maximum size?
Within 5%, 10% or 20%.
97
Teacher’s Section
Requirements
Activity I
Round apples, sharp knives, wood blocks (or upside down trays) to save
the bench being cut.
Rulers and Callipers (see appendix 1)
Activity II
Lined A4 paper, compasses for drawing circles
Activity III
Slices of real conglomerates or photos
Notes
Activity I is more fun but activity II gives better results. You will need
to explain what a frequency graph is. Students taking maths could
compare the experimental result with the theoretical result using
integration.
Results
Average size is 78.5% of maximum diameter and about 40% of
measurements will be more than 90% of the original diameter.
To get the real average size multiply by the reciprocal of 78.5%.
The maximum size will be within 5% of real size.
Time
Activity I 15 minutes, activity II 30 minutes, activity III 30 minutes
98
IMBRICATION
Purpose
To determine the effect of water movement on the arrangement of flat
pebbles. To use this information to deduce the direction of water flow in
sedimentary rocks.
Instructions
Activity I
1
Set up a table like this
Run
Dipping
Dipping down
no.
upstream
stream
Water flow ->
Water flow ->
Pebbles ///
Pebbles \\\
1
2
3
total
vertical horizontal
Sloping
sideways
2
Place the counters in the end of the trough.
3
Fill the jug with water and pour it quickly into the top of the trough
above the counters.
4
Count the counters and fill in the table. Make sure that you are
clear about which are dipping upstream and which are dipping
downstream. It is easy to confuse the terms.
5
Repeat instructions 2 to 4 two more times.
6
Draw your conclusions.
Activity II
1
Mark the long axis of 30 pebbles on the photocopy.
2
Copy and fill in this table and make a tally of the direction of dip of
the pebbles.
Dipping left
horizontal
Dipping right
3
Deduce which way the water was flowing.
99
Teacher’s Section
Requirements
A piece of flat bottomed guttering at least 1m long with a stop end
20 or so counters about 1cm diameter
1 litre jug
Block of wood about 10cm by 5cm by 5cm to support end of guttering
Sink.
Tray under upper end to catch splashes.
Photocopy of a block of breccia showing imbrication.
Making the equipment (10 minutes)
Cut a piece of flat bottomed guttering 1m long and fit a stop end to one
end. Cover the bottom of the inside with Unibond glue and press pebbles
into it. The pebbles should be the same size as the counters.
Notes
Students must use diagrams both in their hypotheses before the
experiment and in their results to make it quite clear how the slope of
pebbles relates to the direction of water.
The evidence derived from this experiment can be confirmed by looking in
the banks or bottom of any stream carrying tabular pebbles.
This activity is useful to do before looking at breccias and conglomerates.
Results
Ignoring those dipping sideways or vertical or horizontal 95% or so of the
remainder should be dipping upstream.
Time
20minutes
Cost
Guttering £8 for 2m
100
Imbrication (slope is exaggerated)
Stop
End
Pour water
Pour
here
Water
Put counters
Here
Put
here
Grains
Here
Sand
or glued
pebbles
Pebbles
to bottom
Stuck to
Bottom
Block
of
Wood
Flat
Flat bottomed
Bottomed
guttering
Guttering
Bench
Tray
Block of wood
Sink
Box to
Box to catch
counters Catch
Grains
101
MUDCRACKS
Purpose
To study the formation of mud cracks, to determine what controls their
size and to see how modern mud cracks compare with fossil ones.
Instructions
1. Select a board and measure the depth that the clay will occupy. This
is the same as the thickness of the strip of wood on the side.
2. Place some mud on the board and roughly level it with the trowel.
3. Level the mud by resting the piece of wood on the side strips and
pulling it over the clay. Fill in any holes and add more clay if necessary
so that the clay covers most of the board.
4. Examine the clay at intervals to see how the cracks develop.
Photograph or sketch the pattern.
5. Once the clay has dried photograph or sketch the pattern of cracks.
6. Measure the maximum dimension of each piece of clay and the number
of sides it has.
7. Look and make an estimate of the number of cracks meeting at each
intersection and the angles between those cracks.
8. Compare your results with students who used different boards.
9. Compare your patterns with photographs of fossil mud cracks.
102
Board for putting clay on
FFirst lift by placing hook next to
the body then with the hook at
the end of the spine
Hard board
strips of wood
Wood strip
103
Teacher’s Section
Requirements
Mud. This can be natural or can be made from cat litter. If the latter
add equal weights of water and cat litter and mix well. Leave for 30
minutes and stir again so that it is a smooth paste.
Boards Two boards 40cm by 40cm with strips nailed to opposite edges
of the top surface. The strips should be 2cm thick on one board and 1cm
thick on the other.
Two boards 25cm by 25cm with strips as above but 3mm and 6mm thick.
4 pieces of wood for levelling 5cm by 1cm , two (for the larger boards)
50cm long and two (for the smaller boards) 35cm long.
Plasterer’s trowel.
Stool
Photographs or examples of fossil mud cracks.
Notes
Shallow trays can be used instead of wooden boards. Students should
wear old clothes or lab coats and the surfaces should be covered with
newspaper as filling the boards can be a bit messy.
It is often best to photograph the mud cracks with a scale and let
students measure enlargements of the photograph.
Results
The deeper the mud the larger the mud cracks. The cracks are V shaped
and pieces of clay tend to curl up so that they are concave. Some fossil
mud cracks show an almost hexagonal pattern. Neither I nor my students
have ever reproduced this. It is now known that the hexagonal pattern
only develops at depth and the top more irregular layer must be eroded
before the hexagonal pattern is exposed.
Thick mud often has two sets of cracks, a smaller thinner set of cracks
surrounded by larger ones.
Time
Setting up tray 10 minutes. Measuring and comparing about 30minutes.
104
RAIN PRINTS
Purpose
To study the formation of rain prints and to work out the conditions
under which they form and may be preserved.
Instructions
1. Spread a thin even layer of clay on the board by placing the piece of
wood on the side strips and pulling it across the clay.
2. Smooth the surface if necessary with the plasterer’s trowel.
3. Place the board out in the rain on a stool until it is covered with pits
but not so many that they are intersecting.
4. Describe their shape.
5. Place a scale beside them and take a vertical photograph.
6. Put the board back in the rain and watch what happens to the pattern
as more and more raindrops fall on it.
7. Enlarge the photograph and measure the diameter of all prints
8. Plot a graph of their sizes and give the maximum, minimum, and
average diameters.
9. Compare your prints with photographs of fossil rain prints.
105
Teacher’s Section
Requirements
Board 30cm by 30cm and at least 1cm thick.
Strips of hardboard 3mm thick, 1cm wide and 30cm long. These should be
nailed with panel pins to opposite edges of the top surface of the board.
Piece of wood 5cm by 10cm by 40cm (10cm larger than the board)
Soft clay, about the consistency of yoghurt.
Camera, one which will focus down to 50cm. A digital camera is good
because you can get instant results.
Plasterer’s trowel.
Notes
Use newspaper on benches to stop mud getting on them. Students should
ideally wear lab coats or old clothes. The mud can be made from cat
litter providing it gives a smooth paste when soaked. Plaster of Paris does
not work well. The trick is to get the mud with the right consistency; too
runny and the pits fill in again, too thick and no prints are made. This
experiment should be done when it is raining. It is not possible to make
raindrops the right size or which fall at the correct speed with a spray
can or nozzle. The board should be placed above ground level to prevent
dirt plashing or being blown onto the clay. Photographs can be enlarged
using a photocopier and students given photocopies.
Results
The largest are about 5mm diameter and the smallest 1mm. The size will
vary with the type of rain.
There is slight rim 0.5 mm high around the circular depression. With
continued exposure the pattern is lost and the surface slightly rough but
with no clear circular depressions.
Time
10 minutes to prepare clay, less than 5 minutes in the rain, 15 minutes to
measure 50 rain drop prints.
106
ARTIFICIAL OUTCROPS
Teacher’s Notes
Purpose
To teach students how to make a geological map. It is often useful to
teach students these skills before they are taken on field trips. If one
happens to teach in Cambridge as I do, real outcrops are many minibus
miles away so I developed these artificial outcrops which can be laid out
anywhere in the college grounds or, using different “outcrops”, in the
classroom.
General Notes
Students should already have been taught how to use the compass/clinos
and they should have had practice at converting field maps with just
outcrops, dips and strikes into a geological map with boundaries between
the rock units.
Checks
It is important to check that they are measuring correctly and that once
they have put on their strike lines they have approximately the correct
structure.
Method I Outside outcrops
Requirements
45cm square slabs of concrete. You will need 2 each of three different
colours. Each slab should then be cut into four 4 equal pieces. They can
be cut using a hammer and a bolster chisel or cut with a disc cutter. This
gives you 24 outcrops. Coloured concrete slabs can be bought at garden
centres. Irregularly shaped outcrops are actually rather better than
square ones. If you want irregular shapes hit the centre of the concrete
slab with a heavy hammer.
Offcuts of wood about 15cm long and of various thicknesses to support
the concrete slabs so that they are dipping. You will probably need about
8 each of 3, 5, 10cm thick.
Black bricks can be used as outcrops of a dolerite dyke and red bricks for
granite outcrops.
You will also need: a map showing paths, trees etc for each pair of
students: a key relating colours of concrete slabs to rock types.
Compass/clinos: note books or clipboards.
107
Layout
The slabs should be laid in a simple pattern. A fold cut by one fault and a
dyke is fine. They should be laid out sufficiently far apart so that it is
not possible to see the pattern without making a map.
Notes
Beware of grounds men and other students moving your outcrops before
your class. To keep the peace it is probably better to tell the grounds
man in advance and be sure to collect up all the outcrops after the
exercise – long grass, concrete slabs and mowers do not go well together.
Irregular shaped slabs are best because if there are straight edges
which are parallel to the strike students tend to measure these rather
than the actual dip and strike.
Time
About 40 minutes to make a field map for 20 outcrops. Another 20 will
be needed to draw on the strike lines and dip directions and to convert
that into a geological map.
Cost
Concrete slabs cost about £2 each
Method II Classroom mapping
Requirements
Compass/clinos
A map of the classroom
Making the outcrops (about 3 hours to make)
Bedding planes
30 pieces of hardboard each about 30cm by 20cm (A4 size), each cut into
an irregular shape but with a flat bottom edge (see diagram). Paint 10
white for limestone, 10 brown for clay and 10 pink for sandstone. Each
piece has a key hole shape cut out to allow it to slot onto the wooden
wedges. The top of the hole should be 8cm from the bottom of the board.
Black card for outcrops of a dyke, red for granite outcrops.
Supports
You will need 5m of planed 10cm by 5cm timber. This is cut in to a variety
of wedge shaped pieces of wood with angles ranging from 10o to 80o. A
2cm round headed screw is screwed into each 8cm from the bottom of
the wedge.
108
Slot to fit
shank of screw
8 cm
Hole
Holetotofit
fit
head
headofof screw
screw
Shaped A4
painted board
8 cm
Wooden Wedge
15 cm
109
Layout
Slot the hardboard pieces onto the wedges to make the outcrops.
Use as large a room as possible otherwise students will be able to work
out the structure without mapping. Use a simple pattern of an asymmetric
fold cut by a fault and a dyke. A chalk line drawn on the table at the base
of the board shows where it should be it if the outcrop gets moved during
measurement.
Notes
For classroom outcrops tables, with metal frames will give erroneous
compass readings. It is possible to simply support the boards on pieces of
wood of various thicknesses but they tend to get moved during
measurement. A further refinement is to drill holes in the wedges so
that G clamps can be used to hold them to the table.
Time
40 minutes to record the details of 20 outcrops.
An artificial outcrop
110
FOLD WAVELENGTH
Purpose
This experiment is designed to show the relationship between fold
wavelength and the thickness of the competent layer. The wavelength is
also affected by the relative strengths of the layers.
Activity
In this experiment folding is simulated by compressing layers of sponge
with layers of rubber or paper between them.
A, B, C, D and E are made of sponge and rubber
F is paper and sponge
G and H are rubber, paper and sponge.
1 Examine and draw the sample or photograph. Note that one bed has
many small folds in it and the other only one. Try to explain how this may
have come about.
2 Take one block of sponge and measure the thickness of the rubber
using the callipers. (If you do not know how to use the vernier scale ask)
3 Place the sponge block in the wooden holder and use the piece of
plywood to compress it, keeping the plywood horizontal.
4 Is the number of folds affected by the amount of compression?
5 Compress the board until it is at the 20cm mark and then count and
record the number of folds. Measure the wavelength and amplitude
6 Repeat for the other sponge blocks except G and H. When using the
narrower blocks put in two at a time.
7 Plot a graph of thickness against wavelength.
8 Squeeze and examine G and H but do not measure them. Sketch one
of them.
9 Write your conclusions explaining why the one bed in the sample has
many small folds and the other only one large fold.
111
Teacher’s Section
Requirements
Sponge pieces
Box as shown below with internal dimensions of 33cm by 20cm by 10cm
Piece of stiff plywood 10cm by 20cm
Sample or photograph of folded strata in which a single thicker bed is
beside a thinner much more folded bed. Good pictures in Carl Weiss
plates 105 and 106 and Roberts p171.
Making the equipment (box 30 minutes, sponge if already cut 30
minutes)
To make the blocks you will need
14 pieces of sponge each 30cm by 10cm by 10cm (obtainable from
furniture shops)
1 piece 7.5 by 10 by 30cm
1 piece 5.0 by 10 by 30cm
3 pieces of 2.5 by 10 by 30cm
and 5 pieces of rubber each 10cm by 20cm but of varying thicknesses
(obtainable from good hardware shops). The thicknesses I use are 1mm,
2mm, 3mm, 4mm, 5mm and 6mm. You will need one of each except for 1mm
and 6mm of which you will need 2.
3 pieces of paper each 10cm by 20cm.
For A to F each piece of rubber or paper should be glued between 2
pieces of sponge. For G and H glue the pieces together as shown in the
diagram.
Box should be made as is shown in the diagram a
Results
The thinner the competent bed the more folds it will form.
Cost
All the sponge £6
All the rubber sheet £5
Time
40 minutes
112
Fold wavelength diagram a
Loose piece
of plywood
20cm by
10cm
mark 20cm above
bottom
Open Box
Internal
Measurements
10 cm x 20 cm x 33
cm
113
Fold wavelength diagram b
10 cm
7.5 cm
10 cm
10 cm
.
5
ARubbe
to E
rub
r
rubber
ber
F Sheet
paper
2.5cm
m
Sponge
10 cm
7.5 cm
2.5cm
sponge
.
5.
Paper
G
6 mm
Rubber
c
m
H
1 mm
Rubber
c c
114
Block H. Two layers of rubber and one of paper between sponge rubber
115
OMISSION AND REPETITION
Purpose
To show how faulting causes omission and repetition of strata on the
surface and in boreholes and to discover how dip direction and type of
fault determine whether omission or repetition occur.
Each set of boards (3 pieces) represents a vertical section through the
rocks, the top edge represents the surface of the ground.
Instructions
Activity I Outcrop data
1 Make out a table as follows with 16 empty rows:
Set no Outcrop or Fault and
Normal or
Omission or
borehole
strata have reverse
repetition
same or
fault
of strata
opposite
dip
directions
2 Take one set and fill in first three columns.
3 Move the side with two parts upward so that the cut is level with the
top of the other side and "erode" upthrown side so that the "ground
surface" is level see diagram a.
4 Look at the beds outcropping and fill in the last two columns.
5 Replace the "eroded" piece, turn the pieces together through 180o
6 Fill in the first three columns and then do instructions 3 and 4
7 Choose another set and repeat instructions 2 to 6
116
Activity II Borehole data
Imagine a borehole drilled vertically downwards so that it passes through
the fault. Would the core recovered from the borehole show repetition
or omission?
1 Take one set and fill in the first three columns.
2 Move the side with two pieces upwards.
3 Place a ruler vertically so that it cuts through the fault plane the
edge of the ruler represents the borehole. Decide whether there
is repetition or omission along the edge of the ruler and fill in the
last two columns.
4 Do all the sets both ways up.
Using your results draw up a list the circumstances when you can expect
repetition and when omission of strata.
Diagram a
original shape
after movement along
fault
after erosion
117
Teacher’s Section
Requirements
Eight pieces of A5 size hardboard cut and painted as in diagrams b and c.
Each layer should be a different colour. The boards should be cut before
being painted. Do not number or letter the beds as they will be used both
ways up. The beds should have a variety of dips. If you paint 16 boards
then they could be lettered which would make it easier for students. Two
hours to make.
Notes
This can also be done as a scissors and paper exercise with the students
copying the diagrams, cutting the faults and folding behind to "erode".
Reverse and thrust faults have the same effect providing the beds have a
shallower angle of dip than the thrust plane. Students find that detecting
repetition is more difficult than the omission for surface outcrops
because they have to imagine the outcrop will extend beyond the edge of
the board.
Results
Normal faults with the strata and the fault having the same dip direction
cause omission in outcrop and repetition boreholes.
Normal faults with the strata dipping in the opposite direction cause
repetition in outcrop and omission in boreholes.
Reverse faults with strata dipping in the same direction cause repetition
in outcrop and repetition in boreholes.
Reverse faults with the strata dipping in opposite directions cause
omission in outcrop and repetition in boreholes
Time
20 minutes for four sets.
118
diagrams b and c
Strata
Line of Fault
Line of erosion
Line for erosion
B
Line of Fault
Erosion
Strata
119
SIMPLE SHEAR I
Purpose
This activity is to show how beds change thickness when subjected to
simple shear.
Activity.
The pack of cards represents a bed which is being progressively sheared.
1. Place the edge of the bar on 0o and push the cards up against it.
2. Measure the thickness between the red lines on the cards at right
angles to the bar using the setsquare.
Plot your results as follows:
angle
thickness
thickness /original thickness
3. Move the cards away from the bar and then move the bar to 5o. Push
the cards against the bar. Do not use the bar to move the cards.
4. Again measure the thickness of the bed using the setsquare.
5. Repeat instructions 3 and 4 for every 5o until 50o.
6. Plot your results on a graph. Plot the angle against new thickness /
original thickness. Leave space on your graph for the angle to increase
to 90o.
7. Work out the mathematical relationship between bed thickness and
angle of shear.
8. Use your information to calculate the shear angle on the limb of a fold
in the sample or photograph. First you will need to measure the
thickness of the bed at the hinge, this will be the original thickness.
Then measure the thickness on the limbs. Make a sketch of the fold
120
Teacher’s Section
Requirements
Shearing box.
A pile of 12.5cm by 7.5cm filling cards enough to fit in the box, that is 6
packs
Set square,
Sample or photograph (Weiss plate 93).
Making the equipment (1 hour)
The wooden box should be 35cm long by 11cm wide by 5cm high and open
at both ends. The arm should be 30cm long. Construct the box as shown in
the diagram. Mark the angle on one side. Fill the box with enough cards
for them to be tight but still to slide. With the arm at right angles to the
side mark two red lines on the top edge of the cards exactly 10cm apart
Side
35 cm x 5 cm x 2 cm
Screw and
Washer
Cards fit
here
Bottom plywood
35 cm x 14 cm
Angles
marked every
5°upto 60o
Arm 30cm by 5cm by
2cm
121
Notes
Simple shear is, as it says shearing, such as occurs in an incompetent bed
during folding.
The experiment “Simple Shear II “ is also about simple shear but deals
with pebbles in a conglomerate. Make sure students do not use the bar
to move the cards as it damages the cards especially at high angles. It
gets difficult to keep the cards together above 50o.
Results
The mathematical relationship is: thickness = 10 Cos angle
Time
About 20 minutes for making the measurements.
Simple shear
122
SIMPLE SHEAR II
Purpose
The purpose of this activity is to determine the amount of shearing that
a metamorphosed conglomerate has undergone.
Instructions
1. Measure the longest and shortest axis of 10 separate pebbles in
your sample or photograph and calculate the ratio (shortest divided
by longest). Tabulate your results (10 lines)
Long
short
Short/long
2. Calculate the average ratio.
3. Use the shear box and cards to measure the deformation of a circle as
it is sheared. Place the arm at 0o and move the cards against it.
Measure the longest diameter and the shortest diameter (the latter
will be at right angles to the former).
4. Move the cards away from the arm and move the arm to 5o. Push the
cards back against the arm. Again measure the maximum and minimum
diameters.
5. Repeat instructions 3 and 4 for every five degrees up to 50o and
record as follows (11 lines)
angle
Longest
Shortest
Shortest/longest
diameter
diameter
6. Plot your data as a graph of angle against shortest/longest.
7. Plot your average pebble ratio on the graph and so determine the
amount of shearing.
8. Think carefully about the experiment and suggest the major sources
of error when using pebbles.
123
Question
Below is a drawing showing the outline of an oolite made from a photo of a
thin section. Oolites are spheres when formed. How much sheering has it
undergone?
Teacher’s Section
Requirements
Slice of a sheared conglomerate or a photograph of one. Weiss has good
photographs on plate 177.
Shearing box See Simple Shear 1 for how to construct one.
A pile of 12.5cm by7.5cm filing cards 11cm thick = 6 packs. Number the
cards so they can be put back in the same order. The cards once placed in
the box should have a 10cm diameter circle drawn on their edges.
Ruler
Notes
Make sure the students do not use the bar to move the cards. This will
bend the card particularly at the higher angles.
Results
Students should make the point that the original pebbles were unlikely to
have been spherical. However the graph could be used for sheared
oolites. The oolite has been sheared by 27o
Time
About 30minutes
124
Simple shear II
125
SLIP BETWEEN BEDS DURING CONCENTRIC
FOLDING
Purpose
To show which of the following variables controls the amount of slip
between beds during concentric folding: 1) curvature at apex of fold,
2) tightness of fold (interlimb angle), 3) thickness of inner bed,
4) thickness of outer bed.
To use this information to calculate the amount of slip on a real fold.
Activity I Folding wooden pieces
This represents folds with angular or broken hinges
1. Take two identical hinged pieces of wood.
2. Measure the thickness of the wood.
3. Hold the wooden pieces loosely so they can slip past each other and
bend them so that the interlimb angle is about 160o. Record the
amount of slip between the ends of the wood. Measure and record the
interlimb angle.
4. Repeat for interlimb angles of about 140o, 120o , 100o, 80o and 60o
5. Repeat instructions 1 to 4 for a pair with a different thickness.
6. Try to work out a mathematical relationship between the angle,
thickness and slip for wooden blocks.
Hinge
Interlimb Angle
126
Activity II Folding Sponge rubber
This represents folds with rounded hinges.
1 Choose two pieces of sponge rubber of the same thickness and place on
top of each other with the sheet of polythene between them.
2 Measure the thickness of the sponge.
3 Hold the sponge pieces loosely so they can slip past each other and
bend them round a 1 litre tin so that the interlimb angle is about 150o.
4 Record the amount of slip between the ends of the sponge and
measure the exact angle. The angle is best measured by placing a
metre ruler beside the straight part of each limb and measuring the
angle of intersection.
Interlimb
angle
Metre
Rulers
Sheet of
polythene
Tin
Sponge rubber
Sponge
Rubber
5 Repeat for interlimb angles of about 120o , 90o, and 60o
6 Now repeat the instructions using a different pair of sponge pieces.
127
Activity III The curvature of the hinge
1. Try bending the pair of thinner sponges around the tins. Use an
interlimb angle of 90o Does the radius of the tin make any difference
to the amount of slip? Record the radius of the tin and the amount of
slip.
Write up
1 Plot your data and draw your conclusions. You should plot:
a) slip against angle, b) slip against thickness of inner bed, c) slip
against radius,
Photographs
1 Calculate the slip between the beds shown in the photographs.
128
Teacher’s Section
Requirements
Two metre rules
Protractor
A variety of sizes of round tins e.g. paint tins
Foam sponge
2 pieces 50cm by 10cm by 7.5cm
2 pieces 50cm by 10cm by 5cm
2 pieces 50cm by 10cm by 2.5cm
One piece of shiny paper or polythene 50cm by 10cm to fit between each
pair
Pieces of wood 2 pairs (that is 4 pieces) 25cm by 3cm by 7cm
2 pairs 25cm by 3cm by 3.5 cm
2 pairs 25cm by 3cm by 1.5cm
Each pair should be hinged together so that they can fold to represent
beds of different thicknesses.(15 minutes to make)
Photographs of folds so that students can work out the slip on them
Notes
Activity I is the easiest to perform
The students then place the wooden pieces on the protractor. Measuring
the interlimb angle for activity II is more difficult and the students will
not be able to make a fold with an exact interlimb angle. It is also
impossible to get the thicker sponges to fold into tight folds
Students can note that the sponge, because it is compressible and
stretchable it forms a continuous fold whereas the inflexible wood
breaks.
Results
The smaller the interlimb angle the greater the slip.
The thicker the inner bed is the greater the slip.
The thickness of the outer limb makes no difference to the amount of
slip.
The shape and diameter of the fold do not affect the slip.
Time
30 minutes for Activity I, 1 hour for activity II and 15 minutes for
activity III
129
Activity II Sponge rubber
Activity I Wooden pieces
130
SQUEEZING PLASTICINE
Purpose
To show how oolites and pebbles change shape when compressed.
Activity
1.
Mark the sides and top of the plasticine cube with a light
impression of circle by very gently pressing the spray can top into
it. Measure the diameter.
2.
Place the cube in the vice with the top of the plasticine about 2cm
below the top of the wood attached to the vice.
3.
Measure the distance between the pieces of wood.
4.
Close vice by 2mm (that is about half a turn). Measure the
distance between the jaws.
5.
Measure the maximum and minimum diameters of the ellipse. This
is easiest if you use the callipers.
6.
Record your data under the following headings.
a
Vice opening
b
opening
original opening
c
max
diameter
d
min
diameter
e
min diam
max diam
7.
Repeat instructions 3 and 4 until the plasticine is about half of its
original thickness.
8.
Plot the data as a graph of column b against column e.
9.
Measure the maximum and minimum diameters of 10 pebbles on the
photo and calculate min/max and work out an average.
10.
Use your graph to calculate how much, on average, the pebbles have
been compressed.
11. Think carefully about the experiment and suggest the major
sources of error.
131
Teacher’s Section
Requirements:
Portable wood vice (Record 12A7 or similar)
Plasticine cube 6cm each side. Make sure the plasticine is soft.
Spray can top about 4cm diameter, at least 2cm smaller than the block of
plasticine
Ruler and callipers
Sample or photograph of squashed pebbles
(Weiss L E, The Minor Structures of Deformed Rocks, has good photos
eg. plates 176 and 177)
Or better still photos of squashed oolites (Cloos E 1947 Geol Soc Am Bull
v58 p843-918)
Results
Pebbles are rarely spherical. If we knew the original shape of the pebbles
it would be possible to calculate the amount of compression. However
oolites are originally spherical. a:c axis ratio of more than 2 so it is
possible to get some idea of the minimum amount of compression.
Notes
A similar experiment can be done using sponge with circles drawn on.
Squeezing the sponge represents the squashing of reduction spots in
shale as it dewaters.
Time
30 minutes
Cost
Vice £20
132
STRESS AND STRAIN
Purpose
To show the relationship of stress and strain.
Stress is the force acting on a unit area of a rock and strain is the
amount of deformation that the stress causes as proportion of the
original size. In this experiment we shall use sponge because rocks need
very high pressures to deform them. The sponge acts like a rock which is
confined so that it cannot spread sideways.
Geological Relevance
It is important to be able to estimate the amount of compression that
the rocks under large buildings such as dams will undergo. Knowing the
amount of strain rocks show geologists can calculate how deeply they have
been buried or how much tectonic pressure they were subjected to.
Instructions
1.
Choose one of the sponges and measure its thickness t0
2.
Remove the pan from the scales and put the larger piece of
plywood on top.
3.
Place the other plywood pieces on the top and bottom of the
sponge and then place the sponge and the plywood pieces onto the
balance.
4.
Set the scales to zero.
5.
Press down lightly on the top piece of wood so that the sponge is
compressed equally all over and the scale reads 1kg.
6.
Record the reading on the balance, this is the force you are
exerting on the sponge. This is the same as the stress if the area
of the sponge is taken as one unit. At the same time use the ruler
to measure the new thickness of the sponge t1.
7.
Increase the force to 2kg and again record the reading on the
balance and the thickness.
133
8.
Repeat these instructions until you have measurements for 5
different forces.
9.
Now choose a different sponge and repeat the instructions.
10.
For each reading calculate the strain (t0 - t1)/t0.
11.
Plot stress against strain.
Plywood
Ruler
Sponge
Scales
134
Teacher’s Section
Requirements
Pieces of different types of sponge each about 5 cm by 10cm by 10cm.
Kitchen scales or any scales or balance reading up to about 5kg.
2 pieces of plywood 10cm by 10cm and one piece slightly larger say 11cm
by 11cm.
Ruler whose length below zero is equal to the thickness of the plywood.
Sponges can be bought in chemists and cut to size using a hot wire or can
be obtained from the specialist companies who supply sponge for
furniture.
Notes
This can be done with weights on top instead of scales but it is difficult
to get the pressure even all round and so the sponge varies in thickness.
Checks
Make sure the students are pressing evenly so that the sponge is the
same thickness all round.
Time
15 minutes for 2 sponges
Results
Ideally each sponge should give a sigmoidal curve but you may only get
part of it. This is because sponge, like rock is not a truly elastic material.
135
strain
Stre
stress
ss
Stress and strain
136
WAVELENGTH
Purpose
To work out the relationship between wavelength, amplitude, dip of limbs
and crustal shortening
Instructions
1 Set out a table with the following headings:
Limb
length
Original
Length
No of
synclines
New
length
amplitude
Dip
angle
Wavelength
Crustal
shortening
2 Stretch the piece of paper out flat and measure the length from A to
B.
A
B
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
3 Stretch out the folded paper at the edge of the desk so that the
wavelength is large. Place a piece of wood at each end and a ruler on top
to make sure all crests are the same height and same spacing.
Wood
Strip
Wood
Strip
Ruler
A
B
Folded paper
Table
4 Count the number of synclines.
5 Measure the length from first crest to last crest and record it.
6 Measure the dip of the limbs
7 Measure the amplitude using the small ruler.
8 Repeat instructions 3 to 6 three more times with shorter lengths
between crests.
137
9 Calculate the wavelengths.
10 Calculate the crustal shortening as a percentage:
original length – new length x 100
Original length
11 Plot wavelength and amplitude against crustal shortening.
12 Draw your conclusions.
13 Calculate the crustal shortening, wavelength and amplitude of the
folds on the photo.
Teacher’s Section
Requirements
A3 piece of paper cut lengthways into strips about 10cm wide. One strip
folded very carefully every 2cm, one every 3cm and the last every 4cm.
Alternatively get strips of sticky labels of different sizes, these fold
very easily and actually work better. There should be an odd number of
folds.
Two 30cm rulers, one which has no space between zero and the end (the
end can be cut off with a fine toothed saw or use a metal ruler).
Small protractor or better a clinometer.
Two small weights to hold paper at set distances; anything will do but
pieces of wood 10cm by 3cm by 2cm are ideal except for the 2cm limbs
when coins or thinner wood are needed.
Photo of highly folded strata (e.g. BGS memoir 307 p43)
Notes
It is more difficult to get an even spread with steeper limbs and probably
less likely to occur in nature. Students need only do one strip, different
pairs of students could do different limb lengths and compare results
Results
Wavelength decreases and amplitude and dip increase with increasing
crustal shortening
Time
60 minutes for all three strips
138
AMMONOID SUTURES
Purpose
To try to explain why ammonoids developed complex sutures. In this
paper exercise you will investigate how the shell strength will change with
increasing crinkling of the suture.
Instructions
Activity I
1. Draw the suture patterns of a goniatite, a ceratite and an ammonite.
Activity II
1. Draw a several separate pairs of V shapes to represent the folded
septa as in the diagram. Keep d1 and d3 constant. Use an angle of 180o
(straight line) in your first diagram and smaller angles down to 20o in
subsequent diagrams. Draw about 6 separate diagrams.
Angle
d2
d3
d1
139
2. Measure the shortest distance between the lines d2.
3. Plot distance against angle
4. Draw your conclusions
5. Work out a formula which relates d2 to the angle and d3
Teacher’s Section
Requirements
A goniatite, ceratite and an ammonite
Protractors
Results
The strength of the shell increases the closer together the septa are so
the more crinkled the sutures are the stronger the shell.
d2 = d3 sine (1/2 angle)
Time
45 minutes
140
ANTERIOR MARGIN
Purpose
Many bivalves and brachiopods have folds in their ventral / anterior
margins. This experiment aims to determine the relationship of the angle
of the fold, the area of the opening, and size of sediment /predator’s
claws that could enter.
Activity 1
To prove that the area of a parallelogram is height x length of base.
1
Measure the height and length of the pack of cards.
2 Push the cards into a parallelogram. The height and length have not
changed. Neither has the area changed regardless of how sharp a
parallelogram you have made.
Activity 2
Sketch the shape of the ventral / anterior margins of the bivalves and
brachiopods provided. Measure the angles of their folds.
Activity 3
1 Draw a series of diagrams like these keeping the opening (o) and the
distance (l) constant and varying angle a from 0o to 70o in 10o steps.
Start with an opening of 3cm and distance 10cm. If you are working in
pairs one person should use 3cm and the other 4cm.
141
d2
d1
o
a
l
2 Draw the largest circle that will fit in the sides and measure its
diameter (d1). The circle represents a sand grain.
3
Draw the largest circle which will fit at the top of the fold (d2)
4 How does the area of the opening and thus the volume of water able
to enter change with change in angle?
5
How do d1 and d2 vary with the angle a.
6
Plot your results and those of your partner. Draw your conclusions.
142
Teacher’s Section
Requirements
Several brachiopods and bivalves .
A4 paper, protractor.
Pack of cards
Compass (for drawing circles)
Sharp pencil
Notes
Suitable brachiopods are Spirifer, Terebratula, Rhynchonella, Pugnax and
the best modern bivalves are Lopha and Tridacna.
This activity can also be done using thin card and cutting out the shapes.
The students always find it difficult to draw the largest circle
accurately.
The conclusions should include some reference to the shells they have
drawn. The anterior fold is also important in holding the valves together
when shut by stopping any sideways movement.
Results
As the angle increases the gaps get smaller. (d1 = o cos a) but the volume
of water that can get in remains the same.
Time
One hour
143
CRENULATION
Purpose
To determine what effect crenulation has on the strength of shells.
Instructions
1. Choose three shells, one with a smooth shell, one with small
crenulations and the last with larger crenulations. Sketch all three
shells.
2. Take a piece of uncreased paper and make a series of zigzag folds in
it. The folds should go across the width of the paper. You will be told
what spacing there should be between your folds. Fold the paper very
carefully and accurately. Make five identical pieces of folded paper.
3. Place a piece of the folded paper on top of the wooden gadget so that
the edges rest equally on each side. Stretch the paper out so that
there is a gap of about 1cm between the crests and place the small
piece of wood on top in the centre. Record the wavelength and the
amplitude.
4. Add twopence pieces or weights in a symmetrical pattern, one at a
time, on to the small board until the paper collapses. Record the final
weight. 2p pieces weigh 7g.
5. Now take a second piece of the folded paper but this time make the
crests 1.5cm apart, place the wood on top and repeat instruction 4.
6. With the third piece make the crests about 2cm apart and again place
the weights on top until it collapses. Repeat so that you fill up one line
of the table below.
144
coin
Small Piece of
Hardboard
Folded Paper
40 mm x 40 mm wood
A4 hardboard
Draw up a table like this and fill the other information from other pairs
of students.
Crest
every 1cm
1.5cm
2cm
3cm
4cm
Folds
every 1cm
1.5cm
2cm
3cm
4cm
7. Draw your conclusions about what is the most effective fold pattern.
145
Teacher’s Section
Requirements
Sheets of thin A4 paper,
A variety of smooth and crenulated shells such as Mytillus, Cardium, and
Pecten.
Piece of hardboard 7.5cm by 10 cm
An A4 piece of hardboard with two pieces of wood 40mm by 40mm fixed
to the long edges.
200 Two pence pieces or 100 10g weights
Notes
The success of this depends on the paper being folded accurately. You
can also try using paper of a different thickness. This works best if one
pair of students folds 5 pieces of paper with 2cm between each fold and
the next pair with 3cm and the next with 4cm etc. Each pair then varies
the spacing of the crests. Results are shared.
Results
Smaller tight folds are stronger but there is some evidence that folds
with a 60o angle are strongest.
Time
1 hour
crenulation
146
CRINOIDAL LIMESTONE
Purpose
The purpose of this activity is to determine if there is any orientation to
the crinoid stems and to measure their size ranges. If a preferred
orientation is found this can tell us something about the wave or current
movement at the time of deposition.
Instructions
1. Measure the orientation by placing the protractor over the crinoid but
with the straight edge on the left side and parallel to the line on the
slab or photograph.
2.
Measure the length, and breadth of the crinoid. Number the crinoid
if using a photocopy of a photograph.
3. Plot your data and explain your results.
Teacher’s Section
Requirements
A large slab of crinoidal limestone, either found in the field or bought
from a stone masons (crinoidal limestone is sometimes called
Hoptonwood). Alternatively a photocopy of a slab has many advantages in
that it can be marked and each student can have his own. The slab or
photocopy should have a straight edge or a line drawn on it. Try to get a
slab which shows some alignment.
Protractors (not small ones)
If you have a weathered slab with the crinoids sticking out it is better to
measure the diameters with callipers.
Notes
Students should realise or be told that those pieces where the length is
similar to the diameter have no significance in determining direction of
water flow.
Time
30 minutes is usually enough
147
THE EVOLUTION OF MICRASTER
Purpose
To determine how the shape of Micraster changed during the Upper
Cretaceous.
Background information
Micraster is found throughout the Upper Chalk. Specimen a is found near
the top and b near the bottom. There is a gradational change from one
form to the other but there is no change in the surrounding sediment.
Instructions
1 Use the British Fossils to identify the two micrasters.
2 Measure the following features of Micraster (a) from a low zonal form
and Micraster (b) a high zonal form. The pieces of wood make measuring
easier for 1 to 3.
1. length
2. width
3. height
4. depth of anterior groove
5. height of the anus
6. distance of the mouth from the anterior end
7. length of the petals
3 Comment on any changes you notice in the plastron, the labrum and the
fasciole.
4 Tabulate and describe your results.
5 Use a text book to obtain an explanation of these changes.
148
Teacher’s Section
Requirements
British Fossils published by Natural History Museum
Plaster casts of Micrasters: a low zonal form such as M.Corbovis or M.
Cortestudinarium and a high zonal form e.g.M Coranguinum. labelled a
and b
Two blocks of wood 5cm by 2cm by 2cm (makes some measurements
easier)
Callipers
A tyre depth gauge fixed into a board is very good for measuring the
depth of the anterior groove ( see appendix 1)
Diagrams to remind them of the different parts of irregular echinoids
Notes
Check the students measurements and understanding of the parts. If
plaster casts or real samples are not available the drawings in "British
Fossils" can provide most of the information. Unless the samples or
diagrams are clear the changes to plastron and fasciole will not be
obvious.
Results
In the higher zonal forms the:
1. length gets longer
2. width gets larger
3. height gets higher
4. depth of anterior groove becomes deeper
5. height of the anus increases
6. distance of the mouth from the anterior end gets smaller
7. length of the petals become longer
In addition the labrum becomes more pronounced, the plastron increases
in size and the fasciole becomes broader
Time
30 minutes
Cost
Micraster plaster casts £7 each
149
EVOLUTION USING DICE
Purpose
Mathematically it is inconceivable that anything as complex as a protein
let alone a cell or creature could arise by chance alone. Natural selection
preserves those aspects which are desirable and eliminates those which
are undesirable. This activity attempts to show how unlikely it is that
animals/cells were formed complete by chance and how much more likely
that they formed by evolution. Each dice represents one aspect of the
creature or cell. In the first activity you are calculating the chance of
developing all ten aspects at once. In the second you are simulating the
development and retention of successful aspects.
Instructions
1 Think of a number ten digits long but containing only the numbers one
to six and calculate the chance of throwing all ten dice at once so that
they come up with your number. It is 1 in 610.
2 Draw a table like this with 20 lines
Dice number
1
2
3
Your number
Number of throws
1
2
4
5
6
7
8
9
10
3 First throw. Take the dice number 1 and throw it. Write down the
number.
4 Repeat with each of the remaining dice, writing the number down in the
same row. If any of the numbers match the digit of your number at the
top of the column, underline it and do not throw that dice again.
5 Second throw. Repeat instruction 4 by shaking each dice in turn except
those that have come up with the correct number.
6 Repeat until the correct number has come up for each column.
7 Compare the total number of throws with the number you calculated
for 610
150
Teacher’s Section
Requirements
Ten dice
Beaker to shake dice in (or use hand)
Tray to shake dice onto (helps prevent them rolling on the floor)
Notes
This can be done with one dice but it is not as visually effective.
Results
Chance of throwing a ten digit number is 1 in 60,466,176 whereas to get
that number by the second method requires on average 60 throws.
Time
15 minutes
151
THE EVOLUTION OF SCREWS AND NAILS
Purpose
To illustrate the ways by which an evolutionary sequence is worked out
from fossils.
Instructions
The screws and nails represent the fossils found in a sequence of five
separate beds.
The bed from which each fossil comes is indicated by the colour of the
paint on it.
The stratigraphic sequence is:
blue represents fossils from the youngest bed
red
grey
green
yellow represents the fossils from oldest bed.
1.
Clear a large area on your desk and place a sheet of A1 size paper
on it.
2.
Examine the “fossils” and list or draw the main variables found in
them.
3.
Sort the “fossils” into groups of like colour. Then spread each
group out in a line so that the lines are in stratigraphic order with the
youngest group furthest away from you and the oldest closest to you.
4.
Try to work out an evolutionary sequence for the “fossils”. Keep
the “fossils” in their lines so that no evolutionary tree has more than five
stages. There is no correct solution but you must be able to justify your
own sequence. Which are the problem “fossils”? Draw lines to show your
evolutionary tree and write what type of change is taking place at each
place on the lines.
152
5.
Try to find examples of each of the following:
continuous evolution
one fossil continuously changing in the same
direction
divergent evolution
one fossil giving rise to two or more new forms
of life.
a radiation
one fossil giving rise to several new forms of
life in a short period of time.
stasis
a “fossil” which remains unchanged for a long
time.
an extinction of a line
A life form ceasing to exist without evolving
into another.
convergent evolution
Separate groups evolving to resemble each
other.
parallel evolution
Separate groups evolving in the same manner.
Requirements
A large variety of nails, tacks, brads, screws, bolts, rivets etc. These
should be chosen so that they show the types of evolution listed in
instruction 5.
5 small screws and nails painted yellow
12 screws, nails and bolts painted green
13 screws etc painted grey
14 screws etc painted red and 15 painted blue. The grey and blue ones
will be mostly larger sizes.
Teacher’s Section
Notes
It is not possible to write a written report but it is possible to put all the
fossils on an A1 sheet of paper to draw onto it the evolutionary tree and
to write on the sheet what changes are occurring. Some of the variables
are:
composition:
steel, brass, aluminium, black painted
length
thickness
shape of cross section: round, oval, square
head: round, countersunk, slotted head, cross head,
type of thread, length of thread
Time
45 minutes
153
EXTINCTION AND CONTINENTAL DRIFT
Purpose
To show the effects of continents coming together on the variety of
species.
Instructions
Each of the four continents has four land animals, four beach and four
shallow marine animals. The species on each continent are different.
Land (terrestial)
Beach (littoral)
Shallow marine (neritic)
Rabbit
limpet
shark
Fox
mussel
fish
Snail
crab
scallop
Bird
sea gull
lobster
As the continents move together the animals are able to compete and
eventually one species of each type survives and the others become
extinct.
The top diagram on the table shows the four islands each surrounded by a
shallow sea and separated by deep sea. Subsequent diagrams show the
shallow seas merging and then the islands touching.
Fill in each of the columns on the table for each arrangement of the
continents.
How does the length of the beach change and how does the number of
species and percentage of littoral species change?
If you were examining a rock sequence which represented the coming
together of two continents would you expect the nonmarine or shallow
marine fauna to show extinctions first?
In what other ways may the movement of continents cause extinctions?
154
1
2
3
4
5
6
7
155
% loss of all
species
Total number
of species
% loss of
marine
species
No of marine
species
% loss of
shallow sea
No of
separate
seas
Shallow sea
area
% land
species loss
No of land
species
No of islands
Patterns of islands
Teacher’s Section
Notes
This is more fun done as a classroom exercise. Students are divided into
four groups. Each group has one continent. They name their animals and
as the continents come together a dice is thrown for each type of animal
to see which survives.
Time
30 minutes to fill in table, one hour if used as a class room exercise.
Results
The total number of species is reduced to 25% of the original and the
length of beach is halved.
Some of the shallow marine fauna would become extinct before the land
fauna. The movement of continents may also cause extinctions because
the climate may change.
156
MEASURING BIVALVES
Purpose
The purpose of the exercise is firstly to describe in both verbal and
statistical terms these bivalves, to make deductions about their mode of
life and the environment in which they lived, and secondly to make
deductions about the fossil assemblage (life or death) from its size
distribution. Bivalves continue to grow throughout their life.
Instructions
These bivalves were all collected from Happylands Quarry, grid
reference 150350 north of Stow on the Wold in Gloucestershire. They
can be found throughout several metres of the limestone exposed in the
quarry but the vast majority are found in a layer about 30 cm. thick,
often in clusters with each individual bivalve in a vertical position. A few
echinoids and brachiopods were found among them.
1.
Measure the length, breadth, and width of the bivalves in the box
you have been given. If the bivalve has been chipped record the
actual length followed by a plus sign, followed by an estimate of the
original length, e.g. 28+ (est 30)
2.
Enter the data into a spreadsheet in 3 columns. Where the bivalve
has been chipped type in the estimated length.
3.
Describe the fossils using appropriate terminology.
4.
Make a labelled drawing of one of the fossils, not a diagram from a
book.
5.
Use the British Fossils books to find the name of the bivalve.
6.
Sort the whole data (i.e. keep the columns together) in order of
length. Plot a frequency graph using the length either by using the
spreadsheet or manually. You will need to group the bivalve lengths
in intervals of 3mm, so you will count, for instance all, those with
lengths of 38mm, 39mm, and 40mm then plot the interval against
the number of bivalves with those lengths.
7
Plot length against width or breadth.
157
8
Deduce the mode of life of the bivalve and whether the populations
are life or death assemblages. Give the arguments both for and
against your decision. Are they all one species?
Teacher’s Section
Requirements
A large number of bivalves, or other fossils all of the same species.
Number each fossil.
Callipers
British Fossils (BMNH) or other fossil identification book.
Notes
You will need to modify the worksheet to suit the fossils you have.
It is best if students measure no more than 20 otherwise they get bored.
Students should record the number of each fossil so you can check on the
accuracy of their measurements. Results can be shared by all students
using a printed sheet or data file. 100 fossils are probably enough. If you
need more for statistical purposes then data can be recorded in advance.
It is also possible to construct two sets so that students can determine
from frequency diagrams if there are two species present.
Results
Depends on the fossils you have used.
Time
About 1 hour for measuring and drawing.
158
ORIENTATION OF BELEMNITES
Purpose
To show the effect of water movement on the orientation of belemnites.
Instructions
Place the belemnites in random orientation scattered over the sand.
Create ripples by moving the water back and forth with the board for
five minutes.
Measure the orientation of the belemnites using a large protractor with
the straight edge parallel to the side of the tank.
Plot your data on a rose diagram.
Teacher’s Section
Requirements
50 small belemnites (Neohibolites type )
Glass tank 50cm by 10cm by 10 cm or plant trough or similar container
Sand to cover bottom of tank to a depth of at least 1cm
Piece of plywood 8cm square
Protractor (8cm radius is good)
Results
Most belemnites align themselves parallel to the ripples
159
SHAKING SHELLS
Purpose
To determine which shells are the most resistant to attrition and thus to
help to explain the proportions of shells preserved in bioclastic and shelly
limestones.
Instructions
Activity I Attrition without the help of stones
1. Select two shells of each type and then weigh each pair of shells.
2. Place shells in the cardboard tube and shake for 1 minute. You must
hold both ends of the tube.
3. Remove the shells but discard all pieces less than 5mm long. Weigh all
the whole or broken shells of each type separately.
4. Replace all the shells and pieces bigger than 5mm back in the tube and
shake them for another minute.
5. Repeat this five times.
6. Plot the percentage of the original weight of each type of shell left
after each throw against the number of the throw.
Activity II Attrition with the help of a stone
1. Place the small stone or marble in with a new set of shells and repeat
the instructions for activity I.
2. Compare the results.
160
Teacher’s Section
Requirements
Four shells of each of the following: cockle, mussel, periwinkle, oyster,
and limpet Many other types of shells would be suitable.
Section of a cardboard tube 20cm long by 10cm diameter with plastic
ends or a plastic bottle with a large screw lid.
Small stone or marble 10mm or less in diameter.
Timer or clock
Balance.
Notes
Often many of the shells remain whole during activity I. The activities
are noisy and may be dusty.
Further work should include looking at the relative abundance of
different shell types in modern and ancient beach deposits and
commenting on them in light of their findings from this experiment.
Results
Limpets and periwinkles are the most resistant to damage, mussels break
most easily.
Time
30 minutes
Credits This experiment is modified from P Kennet and C Ross in
Palaeoecology Longman 1983
161
SHELLS AS WAY-UP INDICATORS
Purpose
To determine if loose valves of Bivalves can be used as way-up indicators
in sedimentary rocks.
Instructions
Activity 1 Wave motion
1. Use the piece of wood to spread the sand out evenly over the bottom
of the plant trough.
Plant
trough
Sand
2cm deep
Water
3cm deep
Move
wood to
make
waves
Shells
either all convex up or
all concave up
2. Place the small valves on the sand in the tank all concave up.
3. Use the piece of wood to make waves but not so vigorously that the
water splashes out.
4. Count how many valves are now convex up and how many are concave
up.
5. Repeat this three times and work out an average.
6. Now place all the valves on the sand in the tank again, but this time all
convex up.
162
7. Repeat instructions 3 to 5.
Activity 2 Breaking waves
8. Use the piece of wood to push all the sand to one end so that it makes
a sloping beach.
9. Place the valves on the sand just above the water on the sand all
concave up
10. Use the piece of wood to make some waves but not so vigorously that
the water splashes out.
11. Count how many valves are now convex up and how many are concave
up.
12. Repeat this three times and work out an average.
13. Repeat instructions 9 to 12 but this time with the valves placed convex
up.
14. Draw your conclusions and explain your results.
Activity 3 Shells on a beach
15. Examine the photograph of shells on a beach and work out what
percentage is convex up and what percentage is concave up.
Activity 4 Working out the way-up of a rock
16. Examine the rock sample and count the number of valves that are
convex up and concave up first on side A and then on side B.
17. Which was the original top of the sedimentary rock?
163
Teacher’s Section
Requirements
Plant trough about 60cm by 14cm by 14cm.
About 1 litre of clean sand preferably white.
Piece of wood 15cm by 8cm to fit easily into the trough.
About 20 small thin valves about 2cm long. Sunset shells and Banded
Wedge shells are good. Mussels also work well or if no shells are available
pistachio “valves”
The sand should be placed in the trough (about 2cm deep) and the trough
filled with 2 litres of water (about 3cm deep).
Photograph of shells on a beach.
Slab of rock full of single valves. My sample came from the Blue Lias at
Blue Anchor near Minehead but I am sure that samples can be got from
many other places.
Notes.
Make sure students understand concave and convex, they often mix them
up.
The effect of marine currents can be simulated in a flume. The valves end
up convex up but are often lost buried in the sand, Pouring water along a
piece of guttering does not work because the concave up valves float.
If there are several pairs of students it is worth having two troughs, one
for each of the first two activities.
Activity 3 can be done on a real beach.
Results
Most of the valves end up convex up because that is the more stable
position. They can be used as way-up indicators. Beware - some Bivalves
e.g. Ostrea and Brachiopods e.g. Productus are found in growth position
but these have both valves together,
Cost
Trough £6
Time
About 45 minutes
164
SPINES
Purpose
To determine whether lateral spines found in some gastropods and
trilobites might have helped prevent the animal from being turned over
by predators or waves.
Activity I
Make sketches of the fossils or modern shells provided.
Activity II
Use the spring balance to find the force necessary to lift up the one side
of the creature, leaving the spines on the other side touching the table.
First lift it up with the hook next to the body. Make measurements for
both the left and right hand side of the body. Then lift it up with the
hook at the end of the spine. Do this for each of the creatures and
record the length of the spines.
Activity III
Put the periwinkles in the tank and make waves without causing the water
to splash out. Which rolls over, the one with or the one without nails.
Repeat the last activity but using two rolls of plasticine one with nails
through it and the other without
Teacher’s Section
Requirements
Examples or pictures of gastropods with lateral spines e.g. Aporhais. See
also plate 61 of British Mesozoic Fossils and plate 20 of British Caenozoic
Fossils.
Examples or pictures of trilobites with lateral spines. See also plates 8, 9
and 10 of British Palaeozoic Fossils.
Spring balance
4 “Creatures” (see below) three with spines and one without
2 periwinkles.
plasticine
Tank or plant trough 75cm long, 15cm wide and 20cm deep
165
Making the equipment (1 hour)
4 pieces of wood 14cm by 4.5cm by 2cm
Cut 6 pieces of wire 5mm diameter (coat hanger wire is suitable) 15cm
long, 6 pieces 10cm long and 6 pieces 5cm long.
Drill 3 holes in each side of three of the pieces of wood. Insert the 6
longest pieces of wire in the first piece of wood, the 6 medium length
pieces in the second piece and the shortest in the third piece. Bend the
pieces of wire so they just touch the table top. Bend the front and back
wires as in the diagram. The forth pieces of wood should have one small
nail in the centre of each side each side hammered in until the head is
3mm proud from the wood. Draw eyes on each piece of wood.
Drill two holes in a periwinkle and put 2.5 cm nails in the holes. Cement
them in using araldite. Make sausages of plasticine 2cm long and 1cm
diameter, put 2.5cm nails through one roll of plasticine.
Notes
Lateral spines may have had other uses such as acting as outriggers when
floating or snow shoes when on soft mud or helping gliding through the
water.
Results
As the length of spines increase so the force needed to lift the
creatures up increases if measured next to the body. The spines prevent
the periwinkles and plasticine from rolling.
Time
30 minutes
Creatures with different lengths of spines
166
167
Side view
Lift creature next to body first and then at end of spine.
Top view
Eyes painted on
4.5cm
Spines
Spines(coat hanger
wire)
14 cm
Wood 2cm thick
168
HUMAN EVOLUTION
Purpose
To determine some of the advantages of becoming bipedal.
1. To measure the amount of the sun’s radiation which falls on bipedal
and quadrupedal forms.
2. To determine the amount of wind available for cooling at 60cm and
100cm above ground level.
3. To measure the advantages of losing body hair and sweating.
Activity 1
1. Make the following measurements of your partner.
Head
a Width (ear to ear, but excluding the ears themselves)
b Breadth ( back to front but not nose)
c Length (top to shoulders)
Torso
Arms
Legs
d Width (side to side)
e Breadth ( back to front)
f Length (shoulder to crotch)
g Diameter
h Length
i Diameter (just above knee)
j Length (crotch to sole of feet)
2. Draw the top, side and front view on graph paper and count the
squares on each. Work out the actual area of your body visible from
above, from the side and from the front.
3. Now use the same figures to draw a quadruped. Average the lengths
of the arms and legs.
169
Alternatively use the following table first for bipeds then for
quadrupeds.
Top
Head
axb
Shoulders
(d-a) x e
total
Front
Face
Torso
Arms
Legs
total
axc
dxf
2(g x h)
2(i x j)
Side
Head
Torso
Legs
total
bxc
exf
ixj
4. Now calculate the area exposed to the sun for top and front and top
and side for each 10o above the horizon.
5. Calculate the strength of the sun for each 10o above the horizon.
When the sun is directly overhead (90o) and there is no cloud the energy
received is 225 watts per square metre.
Make up a table for bipeds and another for quadrupeds with the following
columns. The first column is the angle (a) of the sun above the horizon.
1. Top area
2. Side area
3. Front area
4. Power of sun
5. Energy received on top and side
6. Energy received on top and front
7. Average energy received
170
a
10o
20o
30o
40o
50o
60o
70o
80o
Noon 90o
average
1
2
3
4
5
6
7
Activity 2
1. Use an anemometer to measure the wind speed at 60cm and 100cm
above ground level in an open area. Get an average over several
minutes.
2. At the same time record the temperature at those heights both
with a dry thermometer and with one with a damp tissue around the
bulb.
Set up a table like this
Temperature oC
Dry thermometer
Wet thermometer
Still air
Moving air
3. Record the temperatures shown by the two thermometers
4. Now wait 5 minutes and record the temperatures again.
5. What are the advantages of sweating and standing on two feet?
171
Teacher’s Section
Requirements
2 Thermometers
Tissue paper
Wind speed meter (anemometer). This is not vital.
Notes
Students will need to use trigonometry to find the surface area that at a
given time of day is exposed to the sun. To calculate the sun’s power
assume it is maximum at midday and decreases to zero at dawn and
depends on the thickness of atmosphere it has had to penetrate. Ignore
the curvature of the earth.
Energy received on top (t) and side (s)
= (t x Sin a + s x Cos a ) x 225 x Sin a
Energy received on top (t) and front (s)
= (t x Sin a + f x Cos a) x 225 x Sin a
The last sin a is an approximate reduction due to the thickness of the
atmosphere the sun’s rays must pass through.
Alternatively a spreadsheet can be set up to do all the calculations.
The cooling effect of the wind must be done outside and on a day when
there is some wind. Do not use a fan, fans always warm the air slightly
and do not reproduce natural conditions.
Make sure the water you use for damping the tissue is at outside air
temperature.
A rectangular block of wood stood on its end and a torch will help
students understand the calculations needed.
Results
At midday when the sun is most powerful, the heat received by a biped is
less than a quadruped. The wind speed will be greater at 1.0m than
nearer the ground. The evaporation from the damp thermometer bulb will
reduce the temperature by about 5oC if there is some wind. So standing
upright and sweating can significantly cool the body.
Time
One hour for measurements
Cost
(Anemometer £105. This just makes Activity II better but it is not
necessary)
172
Credit
Based on ideas in the BBC Horizon programme “Some like it hot”
173
DINOSAUR FOOTPRINTS
Purpose
The first part of this activity is an exercise in recording data and the
second part is to see what information can be deduced from footprints.
Instructions
1.
Imagine that you have come across the footprints in a remote area
to which you are never likely to return. Make as many
measurements as you think appropriate and suggest what other
ways of recording the tracks you might consider. (Imagine that
the tracks are real impressions.)
2.
Try to deduce from the prints whether the dinosaur walked like a
crocodile, a dog, or a kangaroo.
Give your reasons.
3.
One method of getting some idea of the size of the dinosaur is to
assume that the height at hip is 4 times the foot length. Calculate
the hip height of the animal using this method.
4.
The graph below shows the estimated weight against hip height for
dinosaurs. Use it to calculate the weight of the dinosaur that made
your footprints.
Graph
Modified from T. Thulborn
100
10
W, body mass 1
(tonnes)
0.1
0.01
1
2
h, height at hip (m)
3
4
174
Teacher’s Section
Requirements
A trail of prints
Tape measures
Reference
Dinosaur Tracks by Tony Thulborn
The book includes lots of examples of tracks.
Making the prints (1 hour )
Decide what type of prints you want: a dinosaur with all prints the same
size or one with larger back than front feet.
Cut the shapes of dinosaur prints out of hardboard. Two holes are drilled
in each. The “prints” are then laid out in a line on grass and 15cm nails put
through the holes to hold them in place.
Alternatively the shape of the print is cut from the centre of a piece of
hardboard 60cm by 60cm and black spray paint used to mark the prints
onto concrete.
Results
Some of the things they should have recorded: track direction, track
length, number of right side, left side tracks, track width, stride
(distance from tip of left toe to tip of next left toe), orientation of feet
to track, length and width of feet, number and length of toes.
Time
30 minutes
175
WEIGHING A DINOSAUR
Purpose
To find the weight of a dinosaur.
This activity also shows how the volume of an irregularly shaped object
can be found and it is a good mathematical exercise in using scales.
Instructions
1.
Fill the displacement can until it just overflows. Wait until it
stops overflowing.
2.
Empty the measuring cylinder and place it under the spout.
3.
Slowly lower the dinosaur until it is completely covered with water.
You may need to press it down with a thin stiff wire. Do not put
your fingers in the water.
4.
Record the volume of water that is now in your measuring cylinder:
this is the volume of your dinosaur model.
Calculations
If the model was made to a scale of 1 to 40 then to get the size of the
actual dinosaur you will need to multiply the volume of the model by 40 x
40 x 40.
Once you have done this you have the volume of the real dinosaur.
Nearly all living animals have about the same density as water; that is,
they either only just float or just sink. It is assumed that dinosaurs were
the same. One ml of water weighs exactly one gram.
In other words, the weight of your dinosaur in grams is numerically the
same as its volume in ml.
To get its weight in tonnes divide your answer by 1, 000, 000.
176
Teacher’s Section
Requirements
A large displacement can
100 ml or 250 ml measuring cylinder
Small models of dinosaurs, ones which state the scale used
Block of wood to support displacement can
Notes
The volume can also be obtained by weighing the model in air and in water
Results
Depends on dinosaur and model but typically Triceratops 7 tonnes,
Diplodocus 12 tonnes
177
ENVIRONMENTAL INTERPRETATION OF SAND
GRAINS
Purpose
To interpret the environment of formation of sands by matching the
characteristics of the sand to those of known environments.
Instructions
1 Examine each of the modern sands using a microscope. For each note
the following:
a) Environment of deposition
b) Colour
i. Are all the grains coloured? If several colours are
present give proportions.
c) Size
i. Use the grain size card
ii. Give the range and average
d) Sorting
i. Use the sorting diagram to give sorting coefficient
e) Roundness
i. Use the roundness chart
f) Sphericity
i. Use the sphericity chart
g) Composition
i. List the composition of any grains you can identify
2 Use the headings above to describe the grains in the sandstone. Be
aware that the colour of the grains may be due to the cement.
3 Rub a few grains from the sample and then use the data of sands
from known environments to deduce the environment in which the
sandstone was formed.
178
Teacher’s Section
Requirements
1. Modern sand samples. These can be collected in a film canister. But
are best given to students as grains glued to a 5cm by 5cm white card.
Use a glue stick not liquid glue (the latter makes all the grains shiny).
2. Binocular microscope or pocket microscope
3. Grain size card and charts for sorting, roundness and sphericity
4. A loosely cemented sandstone which students can rub the grains off
Notes
Desert, beach, river and glacial work well.
Alternatively students can describe and try to work out the environment
of deposition of loose sands and gravels.
Time
40 minutes
179
HALF-LIVES
Purpose
To show how the numbers of atoms change as a radioactive element
decays.
In this simulation each dice represents one atom and each throw
represents a unit of time. It is assumed that each “atom” has a 1 in 6
chance of decaying during each half life and that if it lands with the 6
face up then it has decayed and it is removed from the group.
Instructions
1.
First make up a table like the one below with about 35 lines for
readings on paper or on a spreadsheet.
throw number
number N of
dice left
number of sixes
running total of
sixes
0
100
0
0
1
2.
Place the dice in the cup and shake them and then empty them into
the tray.
3.
Remove all the sixes and place them neatly on the grid sheet.
4.
Fill in the table for that throw.
5.
Place the dice remaining in the tray in the shaker and repeat the
process. Record each throw even if there are no sixes.
6.
When there are no dice left in the tray plot a graph of your data
with the number of throws along the x axis and the number parent
atoms on the y axis. Draw a best fit curve through the points.
7.
Using the graph, work out the half-life assuming each throw
represents 1000 years. Work out the length of the 2nd and 3rd
half-lives and see if they are similar.
180
Question
If 93.75% of the atoms have decayed to become the daughter atoms how
many half lives have elapsed? Calculate this by imagining you are starting
with 64 atoms.
Teacher’s Section
Requirements
Sets of 100 dice
Tray about 40cm by 30cm size with 5cm high sides
Beaker large enough to contain all the dice
10 by 10 grid with each square the size of a dice
Making Dice (30 minutes)
Buy a piece of hard wood with a square section. Paint one side. Use a
circular saw to cut it into cubes. The painted side is equivalent to “6” in
the instructions above.
Results
The answer to the question is 4 half lives.
Notes
Dice have an uncanny knack of disappearing. If, at the end, students put
the dice on the grid you can check that all are present. The last column in
activity 1 is not strictly necessary but it helps check students’ arithmetic
because at the end it should be 100.
A good reference is “Geochronology” by P. Kennet and C. A. Ross. The
exercise can be further enhanced by students entering their data into a
spreadsheet or specialised graph drawing application so that the final
decay curve is based on a larger sample.
Time
30 minutes
Cost
Dice can be bought from wholesalers in packets of 1000 £28.80 plus VAT
or £4.24 plus VAT per 100.
181
BOREHOLES
Purpose
To locate and describe the oil trap and to suggest the best position for a
production well.
This activity will give you practice in predicting where to drill exploration
bore holes, in contouring the depths to the reservoir bed, in drawing
sections and in locating production wells.
Background
The model represents an area underlain by this sequence
shale
sandstone 150m thick
shale 500m thick
Each centimetre on the ruler and on the board represents 100m
It is your task to detect if there is an oil trap beneath the area . You are
only allowed 30 exploration holes. The depth measured in each hole gives
you the depth to the top of the sandstone.
Activity
1. Place the rod vertically in the hole and measure the depth using the
ruler. The depth of the hole is the reading on the ruler at the top of
the rod when the ruler has the 30cm mark next to the pegboard.
2. Use the co-ordinates to locate the borehole on the map and then plot
the depth.
3. Choose the site for the next borehole and repeat the process
4. Repeat the process until you have drilled 30 boreholes.
5. Contour the data.
6. Draw a section across the map at right angles to the fold or fault. Put
on both the top and bottom of the sandstone. Describe the shape of
the trap.
7. Assume the gas occupies the top 100m and the oil the next 300m. Mark
on the section the parts occupied by the gas, oil and water.
8. Locate the best position for a production well.
182
Teacher’s Section
Wood block to
separate
sheets of
pegboard
Wood block to
keep pegboard
on crate
Peg board
30 cm ruler
Record this
height
Steel rod
Shape
Plastic
Crate
Requirements
A box 50cm by 40 cm by20cm. A plastic crate is good.
Pegboard
Hardboard shapes to fit, one at a time, inside the crate; symmetrical and
asymmetrical folds, fault, or a basin up side down
A 30cm steel rod to fit the holes in the peg board. File end to a blunt
point.
A 30cm ruler marked “top” at 0 end
An A4 map of the top of the box with the co-ordinates marked on
Making the equipment (1 hour)
Fix two pieces of pegboard 2cm apart to cover the top of the crate. Make
sure the holes are fixed exactly above each other. This must fit firmly
183
on the crate but must be removable. Mark A to Z on one edge and 1 to 20
on the other to give co-ordinates.
Checks
Make sure the students have the ruler the correct way up and make sure
they do not cheat by lifting the top and peeking at the structure.
Time
30 minutes
Cost
Crate £6.
Outside view of the box
Some shapes used
184
GAPS CAUSED BY NORMAL FAULTING
Purpose
Firstly to determine what parameters control the size of the gap that
develops when a normal fault cuts two different rock types.
Secondly to determine the effect of varying these parameters.
Background
The angle a fault makes with the bedding is determined by the physical
properties of the rock; it is lower in incompetent strata and higher in
competent strata. This means that movement along the fault causes a
gap to open up if the fault cuts different strata. This gap will fill up with
minerals, usually quartz or calcite but sometimes minerals of economic
importance. Predicting the size of the gap is therefore important for
mining companies.
Activity
1. Look at the model and try to work out what parameters are going to
affect the size of the gap.
2. Choose one of the parameters and draw at least three diagrams
similar to the model but varying the chosen parameter. Use a full
sheet of A4 paper for each diagram.
3. Calculate the area of the gap. The area of a parallelogram is base x
perpendicular.
Teacher’s Section
Requirements
A model of a normal fault like the first diagram cut out of card or
hardboard (15 minutes to make).
Each student requires a ruler (one designed for drawing parallel lines is
best), plain paper, scissors and a protractor.
Notes
Lined paper makes it easier to draw parallel beds.
185
Gaps caused by normal faulting diagram a
Strata before faulting
Bed A
Bed A
Bed b
Bed b
Bed C
Bed C
Fracture plane. The angle varies
with the rock type
Gaps caused by normal faulting diagram b Strata after
faulting
Fault
Bed A
Bed A
Bed b
Bed b
Bed C
gap
Bed C
186
Results
Parameters
Bed thickness Bed A and Bed B
Displacement
Throw
Angle in strata A
Angle in strata B
Increasing thickness of beds and/or, increasing the difference in angle,
increase area of gap and therefore volume of mineralisation. So does
increasing the displacement, but only up to the thickness of the bed then
it decreases.
Time
15 minutes for each parameter
187
ORE GRADE
Purpose
To calculate the percentage of galena in a piece of ore containing only
calcite and galena and to work out the grade of the ore.
Activity
1. Work out the density of calcite using the piece of calcite provided.
First weigh the calcite.
2. Then place the beaker of water on the balance and press the tare
button. Read the balance with the calcite suspended in the water.
The last reading gives the volume of the sample.
3. Calculate the density. Density = weight/volume
4. Work out the density of galena in the same way..
5. Weigh the piece of ore and then calculate its density.
6.
Make a graph to enable you to calculate the percentage of galena in
any sample which is a mixture of only calcite and galena. Plot
percentage of calcite along the y axis from 0% to 100%. Plot the
density on the x axis starting at the origin with the density of
calcite and increasing to the density of galena . Draw a diagonal line
from 100% to the density of galena.
7. Use your graph to work out the percentage of galena in your sample.
8. Check your result by using the following equation to calculate the
percentage by weight of galena in the sample.
Ds = Pg x Dg + (1-Pg) x Dc
Ds = density of sample
Dg = density of galena
Dc = density of calcite
Pg = proportion of galena as a fraction
9. Now try to calculate the percentage of lead in the ore. This would be
its grade. Galena is PbS and lead has an atomic weight of 207 x and
sulphur 32. Therefore the grade = 207/(207+32) x %galena in ore.
188
Teacher’s Section
Requirements
Pieces of pure calcite and pure galena about 5cm by 5cm by 5cm.
A piece of mixed ore about the same size. Each sample should have a
nylon (fishing line) loop about 15cm long attached to it with araldite.
A beaker or coffee jar large enough to fit each sample.
Balance with tare facility if possible otherwise ordinary balance.
Notes
Make sure your samples do not contain any barite or fluorite.
Measuring the density can be done with a normal balance without the tare
facility by weighing in air and water or with a displacement can.
Time
Lab work 15minutes, calculations and write up 1 hour.
189
PLACER DEPOSITS
Purpose
To see how placer deposits are concentrated in different environments.
In these experiments we shall use galena as the placer mineral because it
is easy to see and obtain. (Galena is not found as a placer mineral because
it is easily oxidised and breaks easily along its cleavage planes.) The
sediment you will use has 50% by volume galena and 50% by volume sand.
Activity I Plunge Pool
This activity is designed to show how a plunge pool affects the sediment.
1. Place about 20ml of mixed sand and galena in the bottom of the glass.
2. Place the glass in the plastic box and under a tap.
Diagram a
3. Turn the tap on gradually until lots of grains are ”dancing” in the water
and some are coming over the side.
4. Watch and describe the movement of the grains.
5. Leave the tap running for a few minutes until about half the sediment
has come over the top.
6. Remove the glass from the box and carefully empty the water from
both by pouring it into the other container.
7. Tip the grains out on to the paper in the tray.
8. Use the chart to estimate the percentage of galena that stayed in the
glass and then the percentage of galena that escaped and was caught
in the box.
190
Activity II Stream with ribbed bottom
This activity is to show how ribs of rock (caused by alternations of hard
and soft strata) effect the sediment.
1. Place the grid in the channel with the bars lining up with the marks on
the side of the channel. Place an elastic band over each end to hold
the grid down.
Diagram b
2. Place the closed end of the channel on the wooden block and the
plastic box in the sink under the open end of the channel.
3. Put about 20ml of mixed sand and galena in the channel in the part
above the top rib.
4. Pour water into the top part of the channel above the sediment.
5. Watch what happens to the grains.
6. Continue pouring until all the sediment has moved over the top rib and
most over the second rib.
7. Take off the elastic bands and remove the grid.
8. Use the chart to estimate the percentage of galena and the
percentage of sand caught above each rib and record them on a table
like this
Upstream end
Downstream end
section
1
2
3
4
5
6
7
8
9
10
11
12
% galena
% sand
Activity III Wind blown
1. This shows how placer deposits, e.g. gold in Australia can be
concentrated by wind action
2. Place 20ml of sediment along the zero line.
3. Use the hair dryer to blow the sediment until it has all moved at least
5cm.
4. Use the card to estimate the percentage of galena in each interval and
record it in a table like that shown above.
191
Teacher’s Section
Requirements
Activity I
Glass with rounded bottom inside about 15cm high
20ml sediment (see preparation below)
Tap and sink
2 plastic boxes about 20cm by 15cm by 5cm (ice cream boxes will do)
White absorbent paper on tray
Percentage of grains chart (on Geosupplies grain size card and in
field geology books)
Activity II
Channel and grid (see preparation below)
20ml sediment (see preparation below)
Plastic box 20cm by 15cm by 5cm
2 litre jug or pipe from tap
Tap and sink
Percentage of grains chart
Block of wood 6cm by 10cm by 15cm
Activity III
20ml of sediment (see preparation below)
Paper 50cm by 120cm (plain (lining) wall paper is good)
Hair dryer
Making the equipment
Sediment. (15 minutes).
Crush some pure galena pieces and then sieve it. The fraction caught on
the 1mm sieve is retained and added to an equal volume of white sand of
the same size. Broken pieces of galena can be obtained from mineral
suppliers
Activity II Channel (1 hour to make)
You will need:
A piece of white guttering 1m long and a stop end
1.2m of 6mm by 6mm strip of wood.
A piece of 5mm thick wood 6cm by 60 cm
Glue the stop end into one end of the guttering.
Mark the side of the guttering with permanent pen every 5cm from the
open end for 65cm.
192
Cut 12 pieces of the 6mm by 6mm wood about 8cm long. The latter should
fit snugly across the bottom of the guttering so you will to have cut the
ends at about 60o and round them with a file or sandpaper. Glue and pin
the short pieces on to the edge of the long piece of wood at 5cm intervals
and at right angles. This is best done by placing the small pieces in the
guttering at the correct intervals and gluing the long strip to them. Pin
each one when the glue has set. The grid is held in place by two elastic
bands.
Activity III Wind blown
Fold paper 10cm from each long edge to make a trough. Draw a line across
the trough every 5cm.
Notes
Use damp sediment to avoid grains floating for activities I and II.
Activity I can be done without a tap just by pouring water from a jug.
The grid in Activity II is not stuck to the guttering so that the sediment
can be easily observed and then removed. It is possible to do activity II
without the grid. The guttering should be almost horizontal and you will
get very good separation but no gradation.
Be careful not to lose any of the grains down the sink or elsewhere
otherwise the percentage of galena will be changed. The galena breaks up
with constant use and the sediment will need to be renewed every few
years. Cassiterite would be much better but is more difficult to obtain.
Results
Activity I Almost 100% separation of sand from galena can be achieved.
Usually the sand in the tray will contain very little galena but there will
still be some sand left in the glass, mostly on top of the galena.
Activity II and III A gradation from almost pure galena at the top to
pure sand lower down.
Time
Activity I 10 minutes
Activity II 15 minutes
Activity III 10 minutes
Cost
Guttering £8 for 2m
193
Placer deposits Activity I
diagram a
Tap or Jug
“plunge pool”
Box or tray
Grains of
sand and
galena
Glass
194
Put
sediment
here
Placer deposits diagram
b
Board
Elastic bands to
hold board to
guttering
Pour
Water
Here
stopend
Guttering
Sink
Plastic
box
“ribs” glued
to board
Bench
Top
Block of
wood
Channel and grid for Activity II
195
RESISTIVITY OF ROCKS AND MINERALS
Purpose
To discover which rocks, minerals and fluids conduct electricity and which
do not. This information is important when using resistivity for
prospecting, either on the surface or down the hole.
Activity I Rock and mineral samples.
Place the two prongs of the meter firmly onto the sample. If there is no
sound, or the needle indicates no conductivity, move the prongs a little to
make a better contact. Record the name of the material and the result.
Activity II Reservoir rocks
As above.
Teacher’s Section
Requirements
Simple resistivity meter. I use a damp tester which makes a noise whose
pitch varies with conductivity. Alternatively a multimeter can be used on a
resistance range
Activity 1
A variety of igneous, metamorphic and sedimentary rocks, say two of
each.
A variety of minerals, all the common sulphides and oxides and a few
other common minerals.
Activity II
Three samples of sandstone and of oolitic limestone, one of each
saturated with formation water (tap water), oil (cooking oil) and gas (air).
Notes
If the students have to identify the samples in Activity 1 then it is a
good revision exercise as well.
Results
No dry rocks conduct electricity except anthracite, all sulphides do
except sphalerite. Oxides sometimes do depending on the sample. Other
minerals do not.
196
Water saturated sandstones and limestones do conduct electricity but oil
and gas saturated ones do not.
Time
2 minutes per sample
Cost
Damp tester £14
197
ANGLE OF REST
Purpose
To determine the angle of rest in loose sediments.
To determine if the angle of rest is affected by grain size, roundness or
sphericity and whether it is different in wet and dry sediments.
Geological relevance
It is important to know the angle of rest because it will determine the
angle of scree slopes, the stability of the sides of slag heaps and of piles
of sand and gravel. It also determines the stability of embankments and
of road cuttings made in loose sediment.
Instructions
Activity I Dry sediment
1. Choose one container and note the grain size.
2. Turn the container until the sediment slides.
3. Use a protractor to measure the angle of slope.
Container
sand
Measure this
Angle
Wooden Stand
198
4. Repeat for all the containers.
5. Use a protractor measure the angle of slope of the sand and gravel in
the photographs.
6. Plot your results and draw your conclusions.
Activity II
Repeat the instructions above using the additional containers to find the
effect of water, roundness and sorting.
Teacher’s Section
Requirements
Activity I
Transparent circular containers. Honey jars or any large diameter
squat container.
Five containers, each containing dry sediment of a different grain size,
say 0.25, 0.5, 1.0, 2.0, 4.0 mm. The containers should be one third
full.
Protractor or angle measurer (see appendix 1).
Photographs of the sides of sand and gravel piles whose grain size is
known and on which a student is holding a metre ruler horizontally.
Supports for the containers (see diagram).
Activity II
Two containers with the same size sediment, one dry and the other half
full of water (seal lid with plumbers’ sealant).
Two containers with the same grain size, one with angular and one with
rounded grains.
Two containers one with poorly sorted and the other with well sorted
sediment.
199
Notes
Activity I is a good experiment because students expect there to be a
difference and there is not.
If you have access to a gravel works it makes a good field exercise to
measure to slopes and grain size. This experiment can be done without
the containers by just gently pouring sand/pebbles onto a sheet of paper
or into a box but it is more messy and more difficult to measure the
angle.
The correct phrase for angle of rest is “static angle of repose”.
Results
Grain size has no effect on the angle of rest. Most sediment rests at
about 35o. The angles are lower under water. Angular grains have a
steeper slope. Damp sand can stand vertically. Poorly sorted sand has a
slightly higher angle
Time
3 minutes per container. 1 hour for 12 containers and 6 photos.
200
Angle of rest
201
LANDSLIDES
Purpose
The purpose of these two experiments is to determine which of the
following factors is most important in determining whether a landslide
occurs: angle of slip plane, weight of overlying strata, roughness of slip
plane surface, water on slip surface or pore pressure.
Activity I uses a “smooth” plane whereas activity II uses a plane with
varying degrees of roughness.
Instructions
Each measurement should be made several times and an average angle
calculated.
Activity Ia To test the effect of weight
1. Place the two tins A with pebbles and B without pebbles on the dry
glass. Hold a clinometer on the top edge of the glass.
2. Lift the end of the glass very slowly and record the angle at which
each tin slips. Catch the tins before they slip off the glass.
Activity Ib To test the effect of lubrication
3. Repeat with the tins on the second sheet of glass and wet the
surface.
Activity Ic To test the effect of pore pressure
4. Place tins C (with no holes) and D (with holes in bottom) at the top
of the wet glass and fill C and then D with water. Put the caps on.
5. Again lift the end of the glass very slowly until each slips and
record the angle. Catch the tins before they slip off the glass.
Glass
Tin
Clinometer
Sink
Clamp Tray
Bench
202
Activity IIa To test the effect of weight
1. Place the clinometer on one end of the larger piece of wood. Place the
smaller piece of wood on top of the larger one so that the pieces of
sandpaper are touching.
Nail
Clinometer
Weight
Shorter piece of wood
Sandpaper
Longer Piece of
Wood
Bench
2. Raise the one end slowly until the block slips and then record the
angle.
3. Place the 500g weight over the nail on the upper block and repeat
instruction 2.
4. Repeat with more weights
Activity IIb to test the effect of surface roughness
5. Repeat with blocks with different grades of sandpaper
203
Teacher’s Section
Requirements
Activity I
2 sheets of 6mm glass 50cm by 30cm supported on a board. Round edges
of glass slightly with carborundum paper. Label one sheet of glass “dry”
and the other “wet”. The latter must overhang a sink or suitable tray.
Clinometer (Maxiclin from Geosupplies works well)
4 tins 17cm high and 10cm diameter (large dog food tins are ideal), two
with lids to reduce water spills.
Tin A half full of pebbles, Tin B empty, Tin C half full of sand (between 1
and 2 mm), Tin D as tin C but with 20 holes less than 1mm punched
into bottom (These can be made with a nail).
Sink.
Activity II
3.6m of planed timber 100mm by 50mm
1m of each of the following grades of sandpaper: 60, 80, 120
12 drawing pins
4 15cm nails
Clinometer
Weights 500g 100g and 200g
Making the equipment for activity II (45 minutes)
Cut the timber into 4 pieces 30cm long and 4 pieces 60cm long.
Cut each piece of sandpaper into lengths of 35cm and 65cm.
Attach the sandpaper to the blocks using the drawing pins.
Drill a 25mm deep hole in the centre of the 30cm block and place the 6
inch nail into it.
Notes
The tins may slip a little before they start slipping continuously.
Clinometers may need shaking a little because sometimes they get stuck.
A more accurate angle can be obtained using a large demonstration
protractor. Students should raise the end of the glass and wood slowly,
the sudden movement of the tin or upper wooden block may alter the
angle they were holding it at.
You can also try varying the amount of water in the tin with holes. An
increase in the volume of water increases the pore pressure and thus
lowers the angle of slip
204
Time
Activity I 20 minutes, Activity II 40 minutes
Results
The angle of the slip plane and the pore pressure have a big effect.
Changing the weight has no effect on the angle of slip because if the
weight is increased so is the friction. Increasing bed roughness increases
the angle of slip when sandpaper is used but the plane wood often has a
higher angle than the sandpaper, Lubricating the surface should lower the
angle but in this experiment capillary attraction sometimes causes the
lubricated tin to slide at a higher angle than the dry tin.
Cost
Glass 6mm thick £5 per
sheet
Landslide using glass sheet
205
Landslide using wooden blocks
206
LANDSLIDES AND STRESS
Purpose
To determine the relationship between the force necessary to initiate
movement and the weight of the overlying strata and the grain size of
the sediment.
Background
The principal force involved in landslides is gravity. The force of gravity
can be resolved into two forces: one acting down the slope trying to
initiate the landslide and the other acting at right angles to the slope
and increasing the friction between the layers.
Side view of apparatus
Box with sides only
Loose
Board
Weight
hook
500N Spring
Balance
Wood Strip
Box with sides and bottom
Gravel or Sand
G Clamp
Activity 1 To determine the effect of the weight of the overlying rock
1. Use the clamp to attach the strip of wood to the bench and place the
lower box beside it
2. Place the open box on top of the box with the bottom and fill with sand
until the top of the sand is level with the line inside the box.
3. Place the loose board on top of the sand and 1 kg weight on the board.
4. Attach the force meter to the hook.
5. Pull on the force meter slowly and carefully and note the reading when
the upper box moves
207
6. Repeat using different weights.
Activity 2 To show the effect of bed roughness and grain size
1. Place the two boxes together as before and fill with fine sand.
2. Place the loose board on top of the sand and 1 kg weight on the board.
3. Attach the force meter to the hook.
4. Pull on the force meter slowly and carefully and note the reading when
the upper box moves
5. Repeat using different grades of sand..
Teacher’s Section
Requirements
1m of wood 20mm by 25mm to make boxes (see below)
Piece of wood 15cm by 2.5cm by 2cm
G clamp
500 N spring balance
Loose piece of hardboard to fit in top box.
Sand of various grain sizes, say 0.5mm, 1mm, 2mm, 4mm
Making the boxes (30 minutes)
Make a box with internal measurements of 10cm by 10cm by 2.5cm with
bottom but no top as in diagram. Sides of a box of the same size with no
top or bottom but with a strong hook screwed into centre of one side.
Results
The force needed to initiate movement increases with the weight added
and with the increase in grain size.
Time
1 hour
208
ROADSTONE
Purpose
To determine the best types of rock for making the wearing course for
roads.
Background
Whereas most rock types can be used for the lower layers of a road, the
rock used for the wearing course has to have very precise characteristics
if it is to be used on important roads. It has to be hard so most minerals
contained in the rock must have a hardness greater than 5. In order to
remain rough and to provide a good grip for the tyres the rock must have
two or more minerals of different hardness. The grain size of the
minerals within the rock must be less than 2mm. The rock must be strong
otherwise the pressure from the tyres would break it up. It must have
low porosity otherwise water will get in and the frost will shatter it.
Lastly tar must adhere well to it so glassy rocks like flint and obsidian will
not do.
Activity I
1 Set out a table like this with 12 lines
rock
grain size minerals with hardness of each
2 Identify the rocks and note their grain size, if too small to measure
put <2mm
3 Identify or look up the mineral composition of each rock.
4 Look up or work out the hardness of each mineral.
5 Now use this data to fill in a table with this format with 12 lines. Put a
tick if the rock has the characteristic.
rock
most
2 or
grain
strong
tar
low
minerals
more
size
rock
adheres porosity
with
minerals <2mm
well
hardness>5
6 Identify the rocks which are suitable for wearing course roadstone.
209
Teacher’s Section
Requirements (see notes)
A variety of rock samples, about 12 is suitable. They should include
dolerite, basalt and greywacke sandstone.
Samples of the minerals found in the rocks.
Mineral hardness testing set.
Notes
This is a good exercise for revision of rocks and minerals. It is simpler,
but not such good revision, if the mineral composition of each rock is
given and also the hardness of each mineral.
Results
Dolerite, basalt and greywacke sandstone satisfy all the criteria.
Time
60 minutes
210
STRENGTH OF AGGREGATE
Purpose
To determine the resistance of aggregate to crumbling under impact.
This test is regularly used by the Ministry of Transport to test road
aggregate and the figure obtained from this test is called the “aggregate
impact value”.
Instructions
Safety. The steel cylinder is heavy and is a potential hazard. It should
stay on the floor except when in use. Keep it lying down. Do not stand it
on its end or put it on the bench.
1. Choose a rock type, sieve the aggregate and keep those fragments
which pass through the 16mm sieve and are caught on the 8mm
sieve.
2. Weight out exactly 100g of these fragments (w1).
3. Place the steel block on the floor in the tray and hold the plastic
tube on the block and put the 100g of rock into the tube.
4. The first person holds the tube firmly pushing it down onto the
block. The second person lifts the steel cylinder and lowers it
slowly into the tube until the line is level with the top of the plastic
tube. The steel cylinder is then dropped.
5. Pull the cylinder up as far as the line and then drop it again.
Repeat this until you have dropped the cylinder 15 times. When
pulling the cylinder up the arrows indicate when you are
approaching the line.
6. Collect all the crushed rock including the dust. Do this by tapping
the tube on the metal block or by poking any fragments that are
jammed in. Sieve all the fragments and the dust through the 2mm
sieve.
7. Weigh both the fraction that passes through (w2) and that which
is larger than 2mm (w3).
8. The aggregate impact value is w2/w1 x 100. Check that w1 =w2+w3
or is within 3g of it.
211
Teacher’s Section
Requirements
Steel cylinder 5cm diameter and about 67cm long, should weigh about
10kg
Steel plate 15cm square 1cm thick
Plastic pipe 48cm long to fit tightly over the cylinder but still allow it to
slip.
Jubilee clip to fit around plastic pipe
Gravel of several different rock types (from driveways or piles beside
roads) If you break up rocks to produce the aggregate for testing
remove any flaky bits.
Sieves 16mm, 8mm and 2mm and pan
Tray larger than 20cm by 20cm by 10cm deep
Balance
Small trays to weigh samples in
Making the equipment (15minutes)
Put a bold line around the cylinder 5cm from the end or so that it has a
fall of 40cm. Put arrows for 5cm above that line to indicate, when the
cylinder is being lifted out, the line has nearly been reached.
Put the jubilee clip on the end of the plastic pipe, it will help prevent it
splitting.
Notes
Steel cylinders can be picked up from metal scrap dealers, the exact size
does not matter but it should weigh about 10kg and you will need a plastic
pipe which fits around it.
The steel cylinder is heavy and is a potential hazard. It should stay on
the floor lying down and not be balanced on its end. Beware of males using
it as a phallic symbol.
There is normally some loss in weight between w1 and w2 + w3. 3% is
acceptable.
The tube will need replacing every so often.
The experiment should be performed outside as it is dusty and the
thumping would irritate nearby classes. I have never had any flying
fragments of rock but safety glasses would be a wise precaution.
Reference
Collis and Fox Aggregates
212
Checks
Make sure students are dropping the cylinder from the correct height.
Results
Basic igneous and granite are the strongest i.e. have the lowest values
Time
15 minutes per sample including all sieving and weighing.
Cost
The steel cylinder will cost £33 if bought new but cylinders can be found
or bought very cheaply from scrap merchants.
Steel Cylinder
Mark on Cylinder
Plastic Tube
Jubilee Clip
100g
Aggregate
Tray
Steel Block
213
Strength of aggregate
214
THE STRENGTH OF ROCKS 1
Purpose
In this activity you will measure the relative strengths of rocks by
dropping a marble onto them.
Background
When the marble hits the rock both the rock and the marble deform
slightly. You will find that the marble will bounce higher on some rocks
than on others. The height of bounce is directly related to the elasticity
(Young’s Modulus) of the rock. There is a positive correlation between
Young’s Modulus and the strength of the rock. The Schmidt hammer used
by professionals to determine the strength of rocks works on the same
principle.
Instructions
1. Take one of the rocks, note its name and briefly describe it.
2. Place the base of the metre rule on the edge of the slab of rock.
3. Trial run: Drop the marble from a height of one metre onto the slab,
while your partner notes the approximate height to which it bounces.
4. Now your partner gets into position looking directly at that height.
5. Drop the marble from one metre, while your partner observes exactly
how high the marble bounces. Do this three times.
6. Repeat instructions 1 to 4 for all the other rocks you have chosen.
7. Work out the average bounce for each rock and then list the rocks in
order of decreasing strength.
8. Draw graphs to illustrate your data.
9. Draw any conclusions you can and suggest why some rocks are stronger
than others.
215
Marble
Height of
Height of trial bounce
Trial Bounce
Eye level
Meter Rule
Rock Slab
216
Teacher’s Section
Requirements
About 12 slabs of rock with flat surfaces. The slabs should be at least
10cm by 10cm and all should be 2cm thick. There should be a variety of
igneous, metamorphic and sedimentary rocks, see notes below
One metre rule, glass marble about 1.5cm diameter, clamp or wall to hold
up the rule.
Notes
This activity works well at the beginning of a geology course.
Slabs can be obtained free from stonemasons but beware that
stonemasons call many rocks “granite” which geologists would not. The
rocks should be on a solid bench or on the floor. It is better if the
activity takes place against a wall because then there is less chance of
the marble escaping.
A steel ball could be used instead of the marble.
Checks
That students are putting the ruler on top of the rock. Also
that they are adjusting the height of their eyes to avoid parallax
problems.
Results
Igneous rocks are the strongest with bounces of about 85cm, then
metamorphic and lastly sedimentary. Conglomerate is very variable
because it depends on which clast the marble hits. Vesicular lava is very
low.
Time
One hour for 12 samples
Cost
Slabs of many rock types can be obtained free from stonemasons.
217
STRENGTH OF ROCKS 2
Purpose
To investigate which of the following factors determine the strength of
rock: crystallinity, grain size, porosity, mineral hardness
Instructions
1 Choose suitable pairs or groups of rocks to check the effects of each
of these variables.
2 Record the following data about each rock
Name of rock
Crystalline or fragmental
Grain size
Minerals and their hardness
Porosity
3 Find the height of bounce of each rock type. Follow the instructions
given in Strength of Rocks 1 but take 5 measurements and record both
the average and range.
4 Draw your conclusions.
218
Teacher’s Section
Requirements
Slabs of the following rocks, preferably all 2cm thick
To test grain size: granite and microgranite or gabbro, dolerite and
basalt
To test the effects of mineral hardness: marble and metaquartzite
To test the effects of porosity: marble, limestone, and chalk or
metaquartzite and sandstone, basalt and vesicular basalt (the porosities
should be given).
Metre rule
Marble
Reference books for hardness of minerals and composition of rocks
Notes
This activity is good for revision of rocks and minerals.
Students often suggest density as a suitable factor to investigate
however it is difficult to evaluate because it cannot be separated from
either porosity or hardness of minerals.
If rectangular slabs are used it is easy to calculate the porosity by the
dry porosity method, see Dry Porosity activity II.
Checks
Those listed under Strength of rocks 1 also check that students have
chosen suitable rocks to determine the effects of each of the variables
Results
Grain size makes no difference. There is a positive correlation between
mineral hardness and rock strength and a negative correlation between
porosity and rock strength. Crystalline rocks are stronger than
fragmental rocks.
Cost
Most slabs can be obtained free as offcuts from stone masons. You will
probably need to get slabs of metaquartzite and microgranite cut. Stone
masons will charge about £5 per cut.
Time
1 hour for choosing which rocks to test and bouncing the marble and
measuring grain size. The students will also need time to find out the
mineralogy of the rocks and the hardness of the minerals.
219
SUBSIDENCE DUE TO CLAY SHRINKAGE
Purpose
To calculate the amount of subsidence that will occur as a result of clay
shrinking as it dries up. The shrinkage may be caused by the weight of
the house, drought or by trees sucking up water or by man draining water
from an adjacent aquifer.
To calculate the change of volume of clay with water loss.
Instructions
1. Make a slab of clay 10.0cm by 2.0cm by 0.5cm by rolling the clay out
on the board between the strips of wood and then cutting it to the
exact size with the sharp knife.
2. Put your initials on it.
3. Weight it, and leave it to dry out slowly for several days.
4. Measure it and calculate its new volume. Work out the percentage
reduction in volume. This should be the same as the cube of the
percentage contraction in length.
5. Clay in the ground can, in effect, only contract downwards, not
sideways. This is because, providing the clay is still plastic, any gaps
produced by horizontal contraction are filled in with clay from above
thus is converted into change in thickness. Calculate the subsidence
of a house built on clay if the top metre of clay dries out. Example: if
a cubic metre shrinks by 2% the new volume is 98x98x98. The new
thickness is then 983/1002 since the area has not changed.
220
Teacher’s Section
Requirements
Clay dug from the ground or potters’ clay.
Balance, rolling pin, two strips of wood 15cm by 2cm by 0.5cm, sharp knife
Paper or board on which to rollout clay
Time
10 minutes initially and then 5 minutes when it is weighed and measured
again.
Notes
Subsidence due to drought or trees or pressure is only possible in older
buildings with shallow foundations e.g. Leaning Tower of Pisa. Many cities,
London, Mexico City, Shanghai, Venice have subsided because of the
water table has been lowered by pumping from underlying aquifers but
then the clay does not dry out completely.
221
SUBSIDENCE DUE TO MINING
Purpose
This activity allows you to explore some of the effects of coal mining
on the land surface. It simulates the effects of starting and then
extending a mine along a coal seam.
Instructions
The wooden strip marked "A" represents the coal seam and pulling it out
represents mining the coal. The rice represents all the rock and soil
above the mine.
1
Check that the top of the rice is level.
2.
Slowly and carefully pull out the long piece of wood marked "A".
Watch what happens to the rice. Stop when you have pulled it out
sufficiently for there to be about 10cm of flat rice in the centre of the
area of subsidence. Make a sketch. Measure the amount of subsidence,
the angle of the slope and the distance of the surface affected either
side of the coal face. Include these figures on your sketch.
4.
Place the strip of rubber with the "buildings" on it just ahead of
the subsided area. Pull the wooden strip out slowly and note carefully
what happens to the houses.
5.
Now describe what happens as mining advances under an area.
Note where the buildings are likely to be under tension and where they
will be under compression. Most buildings are able resist compression
better than tension. so buildings in compressive areas may not show
damage while those in areas under tension will.
222
Teacher’s
Section
Requirements
Glass sheet 6mm thick 30cm by 100cm
Board 32cm by 102cm by 4cm
Wood 2cm by 4cm, one piece 102cm, 1 piece 30cm, 1 piece 27cm long
Wood as above but rebated 5.5 mm
Wood (coal seem) 2cm by 4cm with hole drilled to fit small piece of
dowelling
10 5cm screws, 2 4cm screws
Supports for board, 2 pieces of wood 15cm by 4cm by 2cm
6 kg rice (Sand, however well sieved, gets between the glass and the “coal
seam” and stops it being pulled out)
Strip of thin rubber 1.5cm wide 5cm long with 2 pieces of wood 1.5 by 1.5
by 5cm glued to it (see diagram c)
Making the apparatus (2 hours)
Glue or pin the wood without rebate around edge of board leaving a gap
for the “coal seam” to be pulled out. Place glass on top. Fit rebated wood
over glass and screw down. The fit between the coal seem and the glass
must be tight. Screw on the supports at right angles to the frame. Place
the coal seem so that it underlies all but 10cm as in diagram. Then fill the
area behind the glass with rice.
Notes
Rock gives an angle of about 60o. Rice gives a much lower angle than that.
It is best done as a class demonstration. Students can then come in pairs
and do the measuring and repeat instruction 4 if they want.
A piece of wood which fits tightly over the top can be placed there and
the apparatus turned upside down to allow the “coal seam” to be reinserted without removing the rice.
Reference
Waltham, A. C. Ground Subsidence.
Results
The area affected by subsidence is larger than the area of coal
extracted. The maximum subsidence is the same as the thickness of coal
but occurs over an area smaller than the area of coal extracted. The
ground under buildings first undergoes tension, then tilts towards the
area of extraction and then undergoes compression before levelling out.
223
Time
20 minutes plus time for questions
Cost
Glass £10. Rice £5
224
Side view
Wood
frame
Wood = buildings
glass
Rubber
Rice
Pull
Diagram a
supports
Wooden strip A =
coal seam
225
subsidence due to mining
226
Diagram b
Top view
Backboar
backboard
d
Side
side
Rice
Glass
Screw
Rebated
Side
Rebated
Side
Screw
Diagram c
buildings (wood
1.5cm x1.5cm)
thin rubber or
paper 5cm by
1.5cm
227
HOT ROCK
Purpose
To determine the specific heat of a rock and thus how much heat can be
obtained from a given volume of hot rock.
Instructions
1 Weigh the cylinder of rock and then heat cylinder of rock to about
100C.
2 Set out a table like this with 20 extra lines below
Before adding water to rock
Temperature
of
Temperature
water
rock
After adding water to cover rock
Time
Water temperature
of
Rock temperature
3 Pour 250ml of water into the jug, allow it to reach room temperature
and then record its temperature.
4 Remove the heated cylinder from the oven and place it in the insulated
container with the hole uppermost.
5 Put a small amount of oil into the hole in the heated rock cylinder, put
in the thermometer and close the hole with plasticine. Record the
temperature of the rock.
6 Pour enough water from the jug into the container to just cover the
cylinder.
7 Put the stirring rod around the cylinder and then place the top on.
8 Put the second thermometer through the outer hole into the water.
9 Stir the water and then record the temperatures every minute until
the water and rock temperatures are within 5oC of each other.
10 Record the volume of water left in the jug and calculate the volume
around the cylinder.
228
1
Data manipulation
Plot your data on a graph.
2 Calculate the specific heat of the rock
a. Calculate the amount by which the water was heated by the rock.
b. Calculate the amount by which the rock was cooled by the water.
energy transfer = mass of water in grams x increase in water
temperature in oC x specific heat of water
= mass of rock x reduction in rock temperature in oC x
specific heat of rock
(The specific heat of water is 4.2 joules per gram)
(1ml of water weighs one gram)
3 Assume you have a hundred metric tonnes of rock at 100oC and that
you pump water into it at 20oC. What volume of water can you expect
to pump out at a temperature of 50oC?
Lid
Metal
Stirrer
Thermometers
Insulation
Insulation
2 litre
beaker
Rock
Cylinder
Outer
Box
229
Teacher’s Section
Requirements
Cylinder of rock, about 8cm diameter and 8cm high
2 thermometers, stirrer
Insulated 2 litre beaker.
250ml measuring cylinder.
Soft wire (e.g. coat hanger) to make stirrer
One litre jug
Box 20cm by 20cm by 20cm and insulation
Polystyrene tile
Oil and a small blob of plasticine
Preparation
Heat the cylinder to 100oc prior to the start of the experiment but
students must weigh the cylinder first.
Making the equipment (About an hour to make the box.)
Drill a hole 4cm deep in the centre of one end of the cylinder. The
hole should be just large enough to take a thermometer and you will
need a concrete drill bit and a drill press to do it. Stonemasons will do
it for you.
Either get a block of expanded polystryrene and cut a hole in it to
take the two litre beaker. Or make a box about 20cm by 20cm by
20cm and put the beaker into it surrounded by insulation. Make a lid
from a piece of expanded polystyrene and cut holes just large enough
for the two thermometers and the stirrer.
The stirrer is made from a 60cm long piece of wire bent so that it fits
around the cylinder of rock and in the beaker.
Notes
Rock cylinders can be obtained free of charge from stonemasons.
Plotting a graph enables students to make a more accurate estimate of
the increase in temperature of the water but the calculation can be done
without a graph.
Checks
Make sure the students stir the water before measuring the
temperature.
230
Results
The specific heat of rocks should be about 1.0 joules per g. but results
will vary from about 0.7 to 1.3 because the experiment is not accurate.
Time
40 minutes
231
Apparatus for determining specific heat
Apparatus for determining specific heat showing inside
232
THE POROSITY OF SEDIMENT
Purpose
To determine the porosity of loose sediment.
To determine how grain size, sorting, roundness and sphericity affect
porosity.
Activity
1.
Measure the grain size if not given.
2
Record the volume of sand in the beaker (V)
3.
Put exactly 250ml of water into the measuring cylinder.
4
Pour the water slowly and gently into the beaker until the water is
level with the top of the sediment. If the sediment is < 1mm or if
it is poorly sorted allow the beaker to stand for five minutes to let
all the air escape. Check the water level.
5
Record the volume of water left in the measuring cylinder (A) and
work out the volume of water in the beaker ( =250-A ). Empty the
measuring cylinder.
6
Pour the water very slowly and carefully back into the measuring
cylinder without letting any grains escape from the beaker by using
the piece of plywood. Record the volume of water now in the
measuring cylinder (B).
7
Draw up a table like this.
volume of water between the
250 -A
grains
volume occupied by the grains
V
volume of water that will drain
B
out the sediment
8
Calculate the porosity
=(250-A ) X 100
V
9
Calculate the specific retention
= (250-A –B) X 100
V
10
Calculate the specific yield
=B X 100
V
Repeat with a second beaker
11
233
Teacher’s Section
Requirements
250ml measuring cylinders
Piece of wood 10cm by 10cm
Beakers 200g coffee jars make ideal beakers because they are clear,
robust and free. Each one should be marked at 500ml level by pouring in
500ml of water and marking the top level on the outside with a permanent
marker pen. It is wise to make a small scratch with a flint or quartz
because the pen mark may be rubbed off. It is then easy to see that the
sediment is at the correct level.
Well sorted sediment of different sizes or small marbles or glass beads.
For sorting: one jar of well sorted and one of poorly sediment.
For rounding: one jar of angular pebbles and one jar of rounded pebbles.
For sphericity: one jar of marbles and one jar of pennies (you will need
about £7 worth). Counters would also do.
Notes
If doing porosity and grain size students can put their results on the
board and all can then plot a graph of how porosity, retention, and yield
vary with grain size.
The sediment can be used again before drying to measure specific yield
but not porosity and specific retention.
The sediment must be dried before being stored otherwise it becomes
smelly.
Checks
Make sure that the students have not filled the beakers above the level
of the sediment and that they are reading the water level in the
measuring cylinder at the base of meniscus.
Results
Porosity should not be affected by grain size provided the sediment is
well sorted. Specific yield increases with increasing grain size whereas
specific retention decreases. The porosity is greater in well sorted
sediment and is about 45%.
Roundness does not make too much difference. The difference in
porosity between grains of different sphericity is heavily dependent on
packing, spheres 45%, pennies 30%.
Time
15 minutes for two jars
234
Coffee jars and measuring cylinder for porosity experiment
235
DRY POROSITY
Purpose
The purpose of activity I is firstly to measure the porosity of well sorted
sand before and after compaction, and secondly to see what variation
there is between different grain sizes. In activity II you will measure the
porosity of sandstone and limestone slabs.
Background
It is usual to measure porosity by finding out how much water the
sediment will hold. This method does not use any water but assumes
the sand and sandstone are made of quartz or other minerals which
have a density of about 2.65 and that limestone is made of calcite,
density 2.7.
Activity I Porosity of sediment
1. Weight the empty plastic container. It must be dry.
2. Fill the container to overflowing and level off the sediment using
the edge of a ruler. Do not shake or jog the container.
3. Weigh the container full of sand.
4. Tap the base of the container ten times on the table fill it up again
and level it off as before
5. Weigh the container again
6. Repeat instructions 2 to 5 with a different gain size.
7. Empty the container of all sediment and then fill it brim full with
water. Then pour the water into a measuring cylinder to find the
volume V of the container.
236
Activity II Porosity of rectangular blocks
1. Measure the rock slab and calculate its volume in ml.
2. Find the weight of the rock slab in grams.
Calculations
If the sand or sandstone were completely solid (i.e. no porosity) their
weight would be Volume (V) x density of quartz = V x 2.65.
The fraction of the sediment or rock which is solid is
the actual weight
V x 2.65
And the fraction of the sediment or rock which is air (the porosity) is the
remainder. So the porosity as a percentage is
( (V x 2.65) – actual weight ) x 100
V x 2.65
For limestone use the density of calcite
237
Teacher’s Section
Requirements
Lightweight but rigid plastic cups or containers 300 to 400 cc
Well sorted sediment, preferably quartz sand, 0.25mm to 4mm
Balance
Rectangular blocks of sandstone and limestone
Notes
Make sure that they do not jog the container before the initial weighing.
The same calculations can be used for any shaped piece of rock provided
the volume and the density of the mineral or rock is known.
Results
The porosity for the uncompacted sediment should be between 42% and
50% whereas the compacted sediment will vary from 37% to 46%.
Time
30 minutes for 5 grain sizes.
238
THE POROSITY OF ROCKS
Purpose
To determine the porosity of irregularly shaped rock samples
Activity
1. Weigh the sample with the spring balance in (Wa1)
2. Quickly weigh the sample in water (Ww)
3. Allow the sample to soak in water for at least 15 minutes
4. Dab the surface water from the sample and weigh it in air (Wa2)
The porosity will be the volume of pore space divided by the volume of
the sample. The porosity is normally given as a percentage.
(Wa2 - Wa1 )x 100
Wa1 -Ww
The difference between the mass in air before and after soaking is the
weight of the water in the pores. Since 1 gram of water has a volume of
1cc the volume of the pore space in cc is the same as the added weight in
grams. The volume of the sample will be the weight of the water
displaced by the sample and this will be the difference between the
weight in water and the weight in air.
239
Teacher’s Section
Requirements
Spring balance
Pieces of porous rock with a nylon loop attached with araldite
Beaker large enough to take sample
Notes
Strictly this experiment only measures absorbancy because not all the
holes may be interconnected or the connecting gaps may be too small to
allow the water through.
Oolitic limestone is the easiest rock, fine grained rocks would be better
soaked over night.
This can be made more interesting by comparing the porosity of, for
instance, different types of limestone: bioclastic, oolitic, micrite, chalk
or sandstones of different ages: Longmyndian, Cambrian. Devonian,
Millstone grit, Permian or linking it in with reservoir calculations or rock
strength.
Time
15 minutes
Results
Most sandstones and oolitic limestones have porosities of between 5 and
15%
Variations
It is simpler for students to understand if rectangular pieces of rock are
used. They measure the rock’s volume and then work out the change in
weight.
240
FLOW OF WATER AND OIL
The purpose of these five experiments is to demonstrate the effects of grain size,
sorting, length, cross sectional area, pressure and temperature on the flow of water or
oil through an aquifer or reservoir bed.
Activity I To determine if the grain size of well sorted sand affects its
permeability.
1. Record the grain size and the thickness of sediment in the tube. All the tubes
contain well sorted sand.
2. Fill the tube containing the finest sediment up to about 2cm above the top line
with distilled water. Start the timer as soon as the water reaches the top line.
Measure the time it takes for the top of the water to fall to the top of the
sediment.
3. Do the same for the other tubes.
4. Empty water from tray below tubes.
5. Plot and explain your results.
Activity II To determine the relationship between sorting and permeability in sand.
1. Note the degree of sorting of the sediment in the first tube.
2. Fill the tube with water to about 2cm above the top line. Start the timer when the
top of the water reaches the top line. Measure the time it takes for the water to
fall to the top of the sediment.
3. Repeat for the other tube.
4. Empty water from the tray beneath the tubes.
5. Explain your results.
241
Activity IIIa To show the relationship of sediment length to speed of flow.
1. Measure the length of sediment in a tube.
2. Pour 50ml of water quickly into the tube and record the length of time it takes
for the top of the water to sink to the top of the sediment.
3. Follow instructions 1 and 2 for the other tubes.
4
Plot length against time.
Activity IIIb To show how water pressure affects speed of flow.
1.
Quickly pour 25ml water into the tube with the least sediment in it.
Record the time it takes for the top of the water to reach the top of the
sediment.
2. Explain why it takes more than half as long as 50ml.
Activity IV To determine the relationship between cross-sectional area
and volume of transmission and speed of transmission.
1. Fill the largest tube up to the about 2cm above the 20cm mark. Start
the stop watch when the top of the water reaches the 20cm mark and
stop it when the top of the water reaches the top of the sediment.
2. Fill the same tube up again but this time as soon as the water reaches
the 20cm mark place a cup under the tube and start the stop watch.
Remove the cup after 1 minute and measure the volume of water in it.
3. Do the same for the other tubes but this time you can do both 1 and 2
together. Record your results in a table like this.
Diameter
Area
Time
Volume in 1 minute
35mm
962 sq mm
25mm
490 sq mm
15mm
176 sq mm
10mm
78 sq mm
242
4. Plot area of cross section against volume collected in the cup. Explain
your results.
Activity V To show how the temperature of water affects the speed at
which it will flow through sediments.
1 Pour about 50ml of ice cold water through the sand to make
sure the sand is at the same temperature as the water.
2 Now place a small beaker under the tube and then pour in
more ice cold water until the water is 2cm above the top line
making sure no ice is poured in. Start the timer when the
water level has reached the line.
3 Record the time for the top of the water to reach the top of
the sediment.
4 Record the temperature of the water in the beaker after it
has flowed through.
5 Repeat instructions 1 to 4 for hot water and warm water
6 For each calculate the average temperature of the water
flowing through and then plot temperature against time.
Permeability apparatus
243
Teacher’s Section
Requirements
Each activity needs a rack of tubes as described in appendix 1 and below.
Mark each tube 20cm above base.
Distilled water
All activities need a timer and a funnel
Tray below tubes to collect water
Requirements for grain size
4 tubes about 2.5cm internal diameter filled with 10cm of well sorted
sand of the following grain sizes: 0.25 to 0.5mm, 0.5 to 1.0mm, 1.0 to
2.0mm, 2.0 to 4.0mm. The grain size should be marked above each tube.
If you do not have sieves remember it is not necessary to have the exact
sizes quoted. The important thing is to have a range of grain sizes.
Requirements for sorting
2 tubes about 2.5cm internal diameter filled with 10cm of sediment. One
tube should contain well sorted sediment whereas the other should
contain poorly sorted sediment but with the same median grain size.
Requirements for thickness
3 tubes about 2.5cm internal diameter all filled with the same sized
sediment but to different thicknesses. If sand with a grain size between
0.25 and 0.5mm is used then the following thicknesses are suitable:
2.5cm, 5cm, 10cm.
100ml measuring cylinders or clear plastic cups marked at correct level.
Requirements for area of cross section
Four tubes with varying internal diameters; 10mm, 15mm, 25mm and
35mm are suitable. Each tube should be filled with the same sediment, if
sand between 0.25 and 0.5mm is used then a 10cm thickness is suitable.
Plastic cup and measuring cylinder.
Requirements for temperature
3 tubes 30cm long and 2.5cm internal diameter are satisfactory. Each
should be filled to a depth of 10cm with sand about 0.25mm but probably
any sand and any tube would work so long as it does not take too long to
flow through. Use one tube for each temperature.
Hot water, about 50oC; water at room temperature, ice-cold water
244
Results
The coarser the grain size the faster the flow. Fluids flow through well
sorted sand faster than poorly sorted sand. The greater the length
(thickness) the water has to flow through the slower it will flow. Pressure
(including head of water) increases rate of flow, as does increased cross
sectional area. In activity IV the water level should go down at the same
speed in each tube.
Increasing the temperature lowers the viscosity and therefore increases
speed of flow.
Notes
Use distilled water otherwise the sediment clogs up.
Time
About 30 minutes for each activity
245
COEFFICIENT OF PERMEABILITY
Purpose
To see how hydrostatic pressure effects water flow.
To determine the co-efficient of permeability of loose sediment.
Instructions
1 Record the thickness of sediment in the glass tube. Check that the bottom of the
sediment is at 0 on the scale.
2 Record the grain size of the sediment in the tube.
3 Place a container beneath the tube.
4 Fill the tube with water to within 2 centimetres of the top.
5 Start the stopwatch when the top of the water reaches the 140cm point and then
record the time at which the top of the water passes each 10cm interval.
Your record should look like this:
Height of water
Time
cm
secs
140
0
130
23
6 Plot water height (on vertical axis) against time (on the horizontal axis).
7 Why does the water fall quickly at first and more slowly when most of the water has
passed through?
8 Calculate the coefficient of permeability for the sediment.
K =
(h1 - h2) x 2 x L
(t2 - t1) x (h1 +h2)
K = coefficient of permeability
h1 = height of water at time t1 (cm)
h2 = height of water at time t2 (cm)
L = thickness of sediment (cm)
246
Teacher’s Section
Requirements
3 Glass tubes 25mm diameter and 1.5m long
Each tube should have gauze tied over the end and should be
supported on a board 1.8m by 10cm by spring clips as in the diagram.
A tape measure tape should be stuck beside each tube.
Funnel
Glass Tube
Tapemeasure
Tape
Measure
Water
board
Gauze
Sediment
Container
Well sorted sand as listed below. Different thicknesses of sand are
needed to allow for the water to flow through in a reasonable time.
½ to 1mm
30cm
1 to 2mm
45cm
2 to 4cm
80cm
Container to catch water
Funnels and jugs
Distilled water
Timer
Notes
To determine the permeability of desert sandstone or oolitic limestone, use
a disk of rock 1 cm thick. Use sealant to seal it in the bottom of the tube.
The disks can be cut with a pipe hole cutter or chipped into shape. As with
247
most water experiments it is useful to have a cloth available to mop up
spills.
Results
K, the co-efficient of permeability=
1.41 cm per second in sediment 2 to 4mm diameter
0.45
1 to 2mm
0.05
0.5 to 1mm
Cost
Glass tubes £15 each
Time
About 20 minutes per tube
Co-efficient of permeability
248
DARCY’S LAWS OF PERMEABILITY.
Purpose
To determine the relationship between the hydraulic gradient, the length
of the aquifer, cross sectional area of the aquifer and the quantity of
water passing through the aquifer.
Activity
1. Record the diameter and length of the horizontal tube.
2. Saturate the sand until water is coming from the horizontal end by
pouring water into the vertical tube
3. Fill the vertical tube with distilled water until it is just above the
25cm mark.
4. When the water has reached the 25cm mark place the measuring
cylinder under the right hand end and start the timer and keep the
level of the water constant by occasionally adding more.
5. Remove the measuring cylinder after five minutes.
6. Now add more water so that the water level is 50cm
7. Repeat instructions 1 to 4 with the water at 75cm and 100cm.
8. Now repeat the same instructions for tubes with different
diameters and different lengths or obtain the data from other
students. Calculate the hydraulic gradient.
9. Plot three graphs:
a graph of volume of water against tube length and
a graph of volume of water against cross sectional area
a graph of volume of water against head (height of water in
vertical tube)
10
From this information try to derive an equation which relates water
volume to cross sectional area, length and water pressure.
249
Teacher’s Section
Requirements
The apparatus described below.
2 Funnels and a jug
100mm measuring cylinder
Distilled water with a little bleach added
Bowl or beaker to catch water when not being measured
Small G clamp to hold apparatus to table
Wash bottle (useful for keeping water up to required level)
Making the equipment (two hours)
You will need: Clear polythene tube. 2.05m of 3cm and of 1.5cm diameter
tube. 6.70m of 2.5cm diameter tube.
Elbows (right angled junctions). 2 each to fit 3cm and 1.5cm tubes and 8
to fit 2.5cm diameter tubes.
6 boards 1.1m long and 5cm wide marked at 25cm, 50cm, 75cm and 100cm
from one end.
Sealant
Sand 0.25mm
6 L shaped brackets
Gauze. 12 pieces about 6cm square
Take the following pieces of tube and fix an elbow on the end with gauze
between the elbow and the tube.
100cm lengths of 3cm, 2,5cm and 1.5cm diameter tube. 75cm, 50cm and
25cm lengths of 2.5cm diameter tube. When the sealant has set fill the
tubes with sand and shake them to compact the sand. Make sure each
tube is completely full. Use sealant to glue gauze and another elbow on
the other end of each tube. Use sealant to fix a 105cm length of tubing
to one elbow on each tube. Take the board and screw an L shaped bracket
to the zero end. Attach the 105cm tube to the board using clips. The
diagram shows how it should be mounted on the bench. It will take about
2hours to make.
250
Funnel
100
75
Board
50
L
bracket
25
Tube
105 cm
long
Gauze
Sand
filled
tube
Gauze
Elbow
funnel
Measuring
Cylinder
G clamp
Bench
Stool top
251
Notes
There is likely to be some spilt water. This activity works best if pairs of
students do one tube each and then share results using a table like this.
diameter
length volume of water in 5 minutes
25cm
head
3.0cm
100cm
2.5cm
25cm
2.5cm
50cm
2.5cm
75cm
2.5cm
100cm
1.5cm
100cm
50cm
head
75cm
head
100cm
head
To save time the water should be poured in before hand so that it has
time to soak the sand.
Results
The volume of water (V) increases with diameter (d) and head (h) but
decreases with length (L) of tubing. V= k x d x h
L
(k= coefficient of permeability, a constant for a given sand )
Cost
Tubing and connectors cost £20
Time
45 minutes to do one tube (4 readings)
252
CAPILLARY MOVEMENT
Purpose
To show how water rises in sediments of different grain size.
Activity I
1. Examine the level the water has risen to between the glass sheets.
The water has risen because of capillary movement. Measure the
height of the water at each of the lines.
2. The glass sheets are 0.5mm apart at the one end and touching at the
other and the glass 30cm long. Calculate the gap at each line.
3. Plot the height of the water on the vertical axis against the width of
the gap on the horizontal axis. The vertical axis for the height of
water should go up to 30cm. Draw a best fit line through your points
and extend it to 30cm.
Activity II
1. Pour distilled water into the tray to a depth of 1cm.
2. Measure the height the water in each the tube has risen above the
water level in the tray every five minutes for half an hour.
3. Measure the level again after several hours.
4. Plot the height of water against time for each grain size.
5. Use the information from activity I to estimate the effective gap
between the grains for each grain size.
253
Teacher’s Section
22sheets
Sheetsofofglass
touching
glass
Glass Sheets
Separated by
Strip of Metal
touchingtou
ching
Clip
Clip
Water
Tray
Marks
every
6cm
Capillary movement
254
Requirements
Activity I 2 sheets of 4mm clean clear float glass 30cm by 20cm
ideally with the cut edges smoothed. One sheet should be marked with
lines every 6cm.
4 clips to hold the glass sheets together
A thin strip of metal 20cm long and 0.5mm thick
A tray more than 1cm deep and longer than 30cm filled with 1cm of
distilled water
A retort stand or other support to hold the glass vertical
Activity II 4 glass tubes 50cm long, 2.5cm internal diameter, with gauze
tied over the ends. The tubes should be filled with well sorted sediment
with grain sizes of 0.25mm, 0.5mm, 1.0mm, and 2.0mm
Support for tubes as shown appendix 1.
Tray about 1cm deep to fit between supports.
Notes
It is impossible to see the film when the gap is very small and dying the
water does not help.
Results
Activity I should yield a smooth curve with the film getting higher as the
gap gets smaller. The water rises fastest and to the greatest height in
the finer sediment. The water rises fastest in the first 15 minutes but
then slows down to rise slowly over the next few hours.
Time
40 minutes for both activities.
Cost
Glass tubes £20
255
PURIFYING WATER
Purpose
To determine which sand size is best for filtering water. We shall test
the sand for filtering out food colouring which is an organic compound
suspended in the water and for filtering out mud.
Instructions
1. Pour 50ml of dyed water into each of the tubes and keep 50ml as a
control.
2. Collect the water in 100ml beakers as it comes through the sediment
and note any change in colour.
3. Comment the speed at which it comes through each tube.
4. What advantage does each grain size have as a filter.
5. Repeat instructions 1 to 8 but this time use the slightly muddy water.
Stir the water before use.
Teacher’s Section
Requirements
1. Tubes at least 22cm long and about 2.5cm diameter. Each tube should
be filled with a different sand size, say 0.125mm, 0.25mm and 0.5mm.
See appendix 1.
2. Three 100ml beakers or clear plastic cups
3. Water dyed with food colouring (about one drop of food colouring
from disposable pipette per litre of water).
4. Slightly muddy water
Notes
The sand needs washing after the experiments.
Results
Water flows more slowly through the finest sand but becomes clearer.
Time
20 minutes for three tubes
256
CONTAMINATED AQUIFER
Purpose
1 To see how easy it is to contaminate an aquifer and how difficult it is
to clean it.
2 To see if grain size affects ease of cleaning the aquifer.
Instructions
The contaminant we shall use is food colouring. All samples should be
labelled immediately they are collected. The sand in the tube represents
an aquifer.
1. Ensure that the sand is damp by pouring in some water and letting it
drain away.
2. Pour in 50ml of clean water.
3. Keep a sample of the clean water after it has passed through the
sand to compare with the contaminated water.
4. Pour 1ml of the contaminant into the tube.
5. Pour in 50ml of clean water.
6. Collect the fluid in a 100ml beaker.
7. When most of the fluid had drained out replace the beaker and pour
the contents into a boiling tube and label it.
8. Repeat activities 5, 6 and 7 until the water is clean. Check by looking
down through the last sample and the sample of clean water
9. Comment on what you have found.
10. Repeat on a tube with different sized sand.
257
Teacher’s Section
Requirements
50ml measuring cylinder
Food colouring
3 Tubes each filled with a different sized sand and each with gauze to
stop the sand escaping. See appendix 1.
Suitable sizes for the sand 1 to 2mm, ½ to 1mm, and ¼ to ½ mm
Retort stands and clamps to support tubes.
100ml beakers or clear plastic cups
Boiling tubes to save samples in
Notes
Usually at least 1000ml of water needs to be poured in before the water
becomes indistinguishable from clean water. If you really want to show
how difficult it is to clean an aquifer you can also try using fluorocene
which shows up even when very dilute. I have used 1ml of fluorocene
powder dissolved in 5ml of water as the pollutant. Even after 200 litres
of clean water had flowed through there was still a faint greenish yellow
tinge.
Time
30 to 40 minutes per tube (The finer grain size takes longer).
258
RISE AND FALL OF THE WATER TABLE
Purpose
To show the relationship between rainfall and the level of the water
table.
Instructions
1. Set up a table like this with 10 lines
Rainfall (H)
Cumulative rainfall
Height of water table
(in cylinder B)
2. Add 2 or 3 cm of water to cylinder A and measure the height H of
the water.
3. Pour this into cylinder B. This is equivalent to rainfall of H cm because
both cylinders have the same diameter.
4. Measure the height of the water table in cylinder B.
5. Repeat instructions 2 to 4 until the water table is close to the top of
the sediment.
6. Now record the volume of the sediment below the water table by using
the volume scale on the measuring cylinder.
7. Carefully drain the water out using the board to prevent the sediment
escaping. The water should be drained into cylinder A. Record the
volume of water using the volume scale on the measuring cylinder.
8. Plot a graph of water table height against cumulative rainfall.
9. Convert the total rainfall to total volume of water added by marking
the total rainfall on the height scale of the measuring cylinder and
reading the corresponding volume on the volume scale
10.You now need to calculate the porosity of the sediment. The porosity is
volume of water added x 100
volume of sediment filled with water
259
11. Describe the relationship between the rainfall, the change in height of
water table and porosity in words.
12.What is the mathematical relationship between rainfall, porosity and
change in height of water table?
Questions
1. The diameter of the two cylinders is the same. Explain why the
change in level is much greater in the gravel than in the measuring
cylinder.
2. If the sediment were well sorted sand instead of gravel would the
amount of rise or fall of the water table be different? Explain.
3. If the porosity of the sediment were only 15% would you expect the
rise of the water table to be larger or smaller or the same?
4. In May 1992 Anglia Water reported that the water table in parts of
Cambridgeshire was 26 feet (7m ) below its normal level for that time
of year. If the soil porosity is 10% how many centimetres of rain is
needed to restore the water table to its normal level?
Teacher’s Section
Requirements
2 large measuring cylinders, preferably 2000 ml.
One labelled A should be empty and the other, labelled B should be filled
with well sorted pebbles about 8mm diameter. Both should have a
centimetre scale stuck on them (scalafix selotape).
1 piece of board 10cm by 10cm.
Results
The change in height of the water table = the rainfall
porosity
where the porosity is given as a fraction e.g. 40/100
Time
30 minutes
260
Cylinders for rise and fall of the water table
261
EARTHQUAKE
Purpose
To simulate the movement of an earthquake and to investigate the
relationship of the fault displacement to the following:
friction
compressibility of the crust
velocity of movement of crust
frequency of movement
applied force in the direction of movement
The amount of friction is related to the force perpendicular to the fault
plane and the roughness of the fault plane. In this experiment the
perpendicular force is increased by adding weights to the upper piece of
wood and the roughness of the fault plane by using different grades of
sandpaper.
The compressibility of the crust is simulated by the elastic bands or
spring balance and can be altered by adding extra bands.
The velocity of movement of the crust is simulated by pulling the block
over the sand paper.
The fault displacement is measured by marking the position of the block
each time it stops and from this the frequency of movement can be
calculated.
The force is measured both immediately prior to movement and
immediately after by noting the reading on the spring balance.
General Instructions Varying the elasticity, velocity and force
You will need a trial run.
1. Draw up a table like the one on the next page.
2. Choose one of the factors as a variable and keep the others fixed.
262
Sandpaper grade
Length of time
weight
elasticity
number of stops
total length of movement
average displacement
velocity of movement
maximum slip
minimum slip
Sandpaper
weight
Hooks Elastic
Band
Winch
String
Block
Bench
G Clamp to Hold
Sandpaper
G Clamp to Hold
Sandpaper and
Winch
3. Set up the apparatus as in the diagram. Always use at least 500g
weight on the blocks. Use bluetack to hold a 1m strip of till roll
paper along the side of the long piece of sand paper.
4. Mark both on the table and on the till paper your name, the
sandpaper grade, the number of elastic bands and the weight on
top.
5. Start the stop watch and turn the handle to pull the block of wood.
The handle should be turned slowly (one turn per ten seconds or
less) and continuously without slowing or stopping. If the block
263
starts to slide continuously you are turning the handle too fast and
you should stop and start again.
6. Mark each stop point on the till paper.
7. When the wood is nearly at the end stop the stop watch and stop
turning the handle.
8. Complete the table.
9. Repeat the experiment two more times and then change your
variable by adding another elastic band or by adding a weight. Either
replace the till roll strip or use a different colour the mark it.
Instructions for varying the elasticity
Use either one, two, three or four elastic bands of the same size
together on the same hooks. You can put the bands in a line to represent
a rock with high elasticity (compressibility).
Instructions for varying the frictional force
Use 0.5, 1.0, 1.5, or 2kg placed on top of the wooden block.
Instructions for varying the roughness of the fault plane
Use different grades of sandpaper. The sandpaper for block and the
strip should be the same.
Instructions for measuring the velocity of movement
Do one run turning the handle very slowly, then next turning it at twice
the speed, say one turn every 10 seconds and one turn every 5 seconds.
Instructions for measuring the maximum and minimum force
One person turns the handle, and the other marks the till roll, watches
the spring balance and writes down the minimum and maximum force.
You will need a trial run.
1. Set up the apparatus as in the diagram but replace the elastic
bands with a 20 Newton spring balance. Do not use the stop watch.
2. Turn the handle very slowly. Stop turning as soon as the block
begins to slide
264
3. Note the maximum force, just before the block slips, and the
minimum immediately after it slips.
4. Mark the new position of the block on the till strip and measure
the displacement
5. Complete the table for 50 movements.
weight
Sandpaper grade
number
Maximum
Minimum
Change
force
force
force
in displacement
1
6. Add an additional weight to the block of wood and repeat these
instructions.
265
Teacher’s Section
Requirements
Three blocks of wood 5cm by 10cm by 30cm
Spring balance for 20N
timer
Four identical elastic bands each about 5cm long
String, 3 pieces 1m long and safety pins to attach string to elastic bands
Winch (see below)
2m strips of till roll
Weights 0.5 to 2kg
Sand paper strips of various grades, say 60, 80, 120. For each grade:
One strip 1m long and one 35cm the latter fixed to the wooden
block.
2 G clamps, Blue tack or masking tape to hold till strip down
Strip of wood 5cm by 3cm by 1cm to hold sandpaper strip down.
Making the apparatus (2 hours)
Use 4 drawing pins to attach 35cm piece of sandpaper to wooden block
and then screw a cup hook into the centre of the end.
The winch is made by bending a piece of aluminium 5cm by 25cm into a U
shape and drilling holes for a crank (see photo). The string should leave
the winch at the same height as the hook on the block. Alternatively the
winch can be made from meccano.
Notes
It is important to stress that the handle must be turned very slowly.
This activity needs to be done in pairs or threes if using spring balances.
Results
There is a clear relationship between the number of elastic bands and the
displacement: the more bands in parallel the less displacement. There is
no relationship between the weight and displacement. Displacement
generally increases with roughness and speed. The greater the change in
force the greater the displacement and the maximum force precedes
maximum displacement which might be useful for prediction.
Time
2 hours but this can be reduced by different groups of students
investigating different variables.
Based an article by M.Hall-Wallace in Journal of Geoscience Education v46 1998
266
THE EFFECT OF EARTHQUAKES ON BUILDINGS
Purpose
To simulate the response of buildings to the shaking caused by
earthquakes and to find out which shapes vibrate least.
Activity
It is the Love and Raleigh waves which only travel along the earth's
surface which do all the damage to buildings.
2 Record the sizes of all the buildings if this data it is not provided.
3 Trial run: increase the speed of vibration slowly and watch what
happens to the buildings.
4 Return the frequency of vibration to 1 hertz and then slowly increase
the frequency incrementally. For each increment record the amplitude of
the vibration of each building as none, slight, moderate or large.
Record the frequency at which each building shows the greatest
amplitude of vibration (resonance).
5 Move the board through 90o and repeat your recordings.
6 Plot your data as you think best.
7 Draw your conclusions.
Question
Explain why in the Kobe earthquake in Japan many of the 20 story
buildings were undamaged but the 10 storey ones were badly damaged?
267
Teacher’s Section
Requirements
Signal generator
Vibration generator.
Cradle for vibration generator
Block 45cm by 10cm by 5cm
Block 30cm by 10cm by 5cm
Plywood or hardboard 30cm by 30cm
Sponge shapes
Making the equipment (2.5 hours including cutting the sponge)
The vibration generator should be placed in a cradle so that it vibrates in
a horizontal plane and this attached to a piece of wood 45cm by 10cm by
5cm. The generator itself is attached to a piece of wood about 30cm by
10cm by 5cm with a cup hook screwed into the end (see diagram).
Rectangular pieces of sponge of different widths, heights and
thicknesses are glued by their smallest ends to a piece of plywood 30cm
by 30cm. The plywood has small holes drilled in the centre of each edge.
These fit onto headless nails on the wooden block so that the plywood can
be turned through 90o. I have the following sizes in centimetres of
sponge shapes but would be quite satisfactory to have half this number:
15 x 2 x 2
10 x 2 x 2
5x2x2
15 x 2 x 3
10 x 2 x 3
5x2x3
15 x 2 x 5
10 x 2 x 5
5x2x5
15 x 2 x 7
10 x 2 x 7
5x2x7
15 x 2 x 10
10 x 2 x 10
5 x 2 x 10
They can be cut from sponge using a hot wire.
Notes
A shake table which would replace the signal generator and vibration
generator can be bought from Middlesex University Teaching Resources f
Results
Tall thin buildings generally vibrate the most and short squat ones the
least. However at certain speeds of vibration the tallest do not vibrate
and the moderate height buildings do. This explains why in some
earthquakes e.g. Kobe the tallest buildings were not damaged but shorter
ones were.
Time
30 minutes
268
Signal
generator
Vibration
generator
Vibration
Headless nail
Sponge shapes
hook
Hook
Block
Block and Cradle
Bench
Plywood
Signal generator, vibration generator and sponge shapes
269
THE SHADOW ZONE
Purpose
To determine how the size of the core and its refractive index control
the start and end of the shadow zone.
In this practical the surface of the earth is represented by the circle,
the core by the beaker of water or resin. The seismic waves
(P only) are represented by light.
Instructions
1. Place your sheet so that the cross on the edge of the circle is
immediately below the filament of the bulb.
2. Measure and record the diameter of a beaker and whether it is
water or resin filled.
3. Place the beaker in the centre of the circle. Make sure the
shadow zone is symmetrical.
4. Mark on the sheet the positions of the start and end of the
shadow zone on both sides. Record on the line the diameter of
the beaker and whether the line is the start or end of the
shadow zone. Use a different colour for each beaker
5
Repeat instructions 2 to 4 for each of the other beakers.
6 Remove the paper and draw lines to represent the ray paths of
the light/ seismic waves by joining the focus to the point marking
the start of the shadow zone for each beaker.
7 Draw lines from the start and end of the shadow zone to the
centre of the circle. Use a protractor to measure and record the
epicentral angles for the beginning and end of the shadow zone
for each beaker. Calculate the beaker size divided by the
diameter of the circle.
270
8 Plot the epicentral angle against the beaker size divided by the
diameter of the circle.
9 The earth has a radius of 6371 km. Using your graph determine
the radius of the core?
10 The accepted radius of the core is 3471km. Why does your result
differ from this? Look at the ray paths for the seismic waves
shown in the diagrams in textbooks.
11 How does the size and refractive index of the core affect the
position of the shadow zone?
12 Draw the ray paths for the end of the shadow zone.
Water
Beaker
or resin
Light
bulb
Paper
Board
A3 paper
degrees marked on outer
edge of circle
centre of circle matched to
centre of beaker
271
Teacher’s Section
Requirements
Light bulb with vertical filament and low voltage source. The bulb needs to
be positioned so that it is close to the paper.
For each student a sheet of A3 paper with a 25 cm diameter circle drawn
on with a cross at the centre and a cross on the circle.
Beakers of different sizes e.g. 2 litre, 1 litre, 500ml, and 250ml filled
with water. 1 litre beaker filled with at least 2cm depth of clear resin
(obtainable from art and craft shops).
Notes
It is better if the degrees are already marked on the circle with 180o
opposite the cross on the edge of the circle. You can enlarge a protractor
by photocopying it so that it fits the 25cm diameter circle.
Checks
Check that the beaker and bulb are positioned correctly.
Check that the students are marking the lines clearly so that they know
which line is which.
Results
As the core gets larger in proportion to the earth the epicentral angle
decreases for the start and end of the shadow zone. The start of the
shadow zone is not affected by the composition of the core, but the
epicentral angle for the end increases with a higher refractive index.
Time
30 minutes
Cost
Resin £12
272
ISOSTASY
Purpose
To determine the relationship between the amount of erosion and the
amount of uplift of the crust and between the amount of deposition and
the depression of the crust.
In these experiments the water represents the mantle, the blocks of
dense wood the crust and the blocks of light wood the sediment or ice.
The weight of the wood (crust or sediment) added must equal the weight
of the water (mantle) displaced.
Activity I To determine the amount of uplift or depression caused by the
thickening of the crust by mountain building and thinning by erosion
1
Place the retort stand in tank.
Wooden
Blocks
Water
Clear
Tank
Retort
Stand
2 Measure the thickness of all the dense blocks (A to D) and then do the
same for the light blocks (E to H). Record the data in the table below.
273
3 Copy and complete this table:
blocks
thickness added (t)
Total thickness added (T)
A
B
C
D
E
F
G
H
height of top of blocks above
water = height of land (H)
change in height of top of blocks
(h)
depth of bottom of lowest block
=base of crust (D)
change in depth (d)
4 Place block A over the retort stand in the water and measure the
height of the top above the water and the depth of the bottom below the
water.
5 Place block B on top of block A. Measure the height of the top of the
highest block above the water. Measure the depth of block A below the
water.
6 Repeat instructions 4 until you have all the blocks of dense wood (A to
D) on top of each other.
7 Now repeat the process adding the light blocks E to H.
8 Plot a bar graph with height above (H) and below water (D) and the
total thickness added (T) on the vertical axis and the stages A to H on
the horizontal axis. Your zero line should be about 1/3 up the page. It
should look like a series of steps which gives you a good visual
representation. Label your lines “level of land before isostatic
adjustment”, “level of land after isostatic adjustment”, “base of crust
after isostatic adjustment”
9 Plot a scatter graph of H and D on the vertical axis against T on the
horizontal axis
10 Find from the graph or from the numerical data the relationship
between the change in height and the thickness added or subtracted, the
density of water and wood.
274
Questions
1 Write an equation to show the relationship of uplift and erosion
assuming the mantle has a density of 3.3 and crust 2.7.
How will the height of a plateau change if 500m of rock are eroded from
its surface?
2 Likewise write an equation to show the relationship of depression and
sedimentation assuming that sediments have density of 2.0.
100 m of sediment are deposited all over the bottom of a large deep lake.
By how much will the depth of the lake change?
3 Write another equation to show the relationship between isostatic
change in sea level and the thickness of ice added. Ice has a density of
0.9.
Parts of Scotland have raised beaches indicating an isostatic rise of the
land of 10m. What thickness of ice must have melted to cause this
amount of uplift?
Teacher’s Section
Requirements
One transparent tank about 50cm by 30cm by 30cm deep filled with
water 20cm deep. The lowest block should not touch the bottom when all
blocks are in the tank.
Blocks of dense wood e.g oak and of light wood e.g. pine.
Retort stand (to hold all the blocks in place.)
Ruler and tape measure
Making the equipment
Four of pieces of hard wood. All pieces of wood should be 10cm long by
7cm wide and of varying thicknesses, say 5cm, 3cm, 2cm, and 1cm. All
pieces should have a hole drilled through the centre so that they fit
easily over the retort stand and should be labelled A thickest to D
thinnest. The wood should not have knots because these will make it float
unevenly. Four pieces of soft wood 10cm by 7cm, 5cm, 3cm, 2cm, and 1cm
thick, again with a hole in, labelled E to H.
Notes
Unless you wish the students to calculate the density of the wood it
should be worked out before and given to them. The density of any wood
can easily be found by finding what proportion lies below the surface of
the water.
275
With less bright students it is better to give them the equation and ask
them to confirm it. It is easiest to measure the depth below water using
a tape measure and the height above using a ruler.
Results
The equation is t (thickness added) x dwd (density of wood) = d (change in
depth of bottom of crust) x dwt(density of water.)
d = t x dwd
dwt
h= t - t(dwd)
dwt
h= height of top above water
Time
About 40 minutes for the practical part
Isostasy; wooden blocks floating in tank
276
THE EFFECTS OF ISOSTASY
Isostasy is the theory that the crust floats on the mantle in the same
way that wood floats on water.
Purpose
To show how isostatic adjustment affects the height and shape of the
land and the ages of the rocks on the surface.
In these experiments the water represents the mantle and the wood the
crust.
Before doing these experiments try to answer the following questions.
1. Why does the continental crust “float” higher than the oceanic
crust?
Activities 1a and 1b
2. What effect will deposition have on the height of the oceanic
crust?
Activity 2
3. What effect will erosion have on the continental crust? Activity 2
4. What effect will erosion of mountainous areas and deposition on
the continental shelf have on the slope of underlying strata?
Activity 3
5. What effect will the formation of ice sheets and their subsequent
melting have on the level of the crust?
Activity 4
6. How can erosion expose, at the surface, rocks which are formed
50km below the surface?
Activity 7
277
Activity 1a
Height of the crust
1. The water represents the mantle and the blocks of wood the crust.
The blocks of wood both have the same density. The oceanic crust
is about 10km thick and the continental crust is on average 35km
thick.
2. Place the blocks of wood in the water and draw them.
3. Why does one block float higher than the other?
Activity 1b
Height of the crust
1. The blocks of wood have different densities but the same
thickness.
2. Place the blocks in the water and draw them.
3. Explain why one block floats higher than the other.
4. Using the information gained from these two activities explain why
the continental crust floats higher than the oceanic crust.
Activity 2 Erosion and deposition a
The thickest block represents the solid crust and the thinner ones
represent the loose sediment deposited on top.
1. Place the thickest block in the water.
2. Add a second block on top of it and note how the position of the lower
block changes.
3. Place a third block on top and again note how the position of the lower
block changes.
4. Remove the upper blocks one at a time and note how the position of
the lower block changes.
5. Repeat the instructions and draw each stage.
6. Relate the changes in the level of the lower block to deposition and
erosion
278
Activity 3 Erosion and deposition b
1. Place the pieces of wood in the tank in the same arrangement as is
shown in the diagram. Make a sketch.
2. Remove the two top layers of the mountain and place them on the
sea bed. This represents erosion of the mountain and deposition on
the continental crust. Make a second sketch.
3. Describe and explain what has happened to the continental shelf.
loose blocks to be removed and
placed on continental crust
Mountain
Crust
Continental Shelf
Water =
Mantle
Glass Tank
50cm long
Activity 4
The erosion of a plateau
In this activity the water represents the mantle, the wood the
continental crust. Note the level of the peak. Simulate the erosion of a
plateau to form a mountain by removing the upper piece of wood. Try to
explain why the peak has risen in spite of the erosion.
279
Activity 5
The effect of ice-sheets
In this activity the water represents the mantle, the wood the
continental crust and the white painted piece represents an ice-sheet.
1 Measure the height of the top of the continent above the mantle.
2 Now place the ice on the continent and measure the height of the
continent again.
3 Describe and explain what has happened.
4 Now melt the ice by removing it and describe what happens this
time.
5 Scotland was covered with a great thickness of ice but there was
no ice south of the Thames. The ice has all melted but the land is
still adjusting the loss of the extra weight. Will Scotland be rising
or sinking compared to southern England? There are many raised
beaches around Scotland’s coastline, each indicating that sea level
was once higher than it is now. Can you show how these are related
to the disappearance of the ice?
Activity 6 The age of rocks at the surface
1 Place all the blocks in the water in the order shown below:
Sedimentary rocks
Slate
schist
gneiss
migmatite
2 Simulate erosion by removing one block at a time.
3 Explain how rocks which are formed 50km below the surface can be
exposed by erosion.
Activity 7 The formation of rift valleys
1 Start with the three pieces of wood together as a single piece of wood.
This represents the plateau before the formation of the rift valley.
Make a quick sketch of it.
280
2 Rift valleys form when the crust is stretched so pull the outside two
pieces of wood slightly apart but keep all three pieces touching.
3 Sketch and explain the result.
4 Below is a cross-section of East Africa. Explain how the formation of
Lake Victoria is related to the formation of the rift valleys either side.
NW
Lake
Mobutu
619m
Lake
Victoria
1134m
Lake
Natron
628m
Sea
SE
Level
Modified from Principles of Physical Geology by A. Holmes 1965 Nelson
281
Teacher’s Section
Requirements
7 glass tanks with internal measurements of 50cm by 10cm by 10cm made
from 6mm glass. (see appendix 1)
Wooden blocks (see below).
Making the equipment
The glass tanks can be ordered from glaziers but are cheaper to make
(see appendix 1).
Wooden blocks.
All blocks are cut from 100mm wide planed timber and should not contain
knots. Planed 100mm timber is usually 95mm and this size allows for
expansion when the wood is soaked.
Activity 1a Two blocks of wood 15cm long, 3cm, and 5cm thick
Activity 1b One block of soft wood and one of oak 15cm by 5cm
Activity 2 Three blocks of wood 15cm long, 2cm, 3cm, and 5cm thick
Activity 3 As in diagram. Central piece is plywood 45cm long 6.5 thick.
Other pieces made from 2.5cm thick wood. Top two layers are loose,
others are screwed and glued. Screws should be positioned symmetrically.
Activity 4 A piece of wood 9.5cm by 15cm cut as in diagram.
Activity 5 Crust 20cm by by 5cm. Ice is white painted wood 20cm by
3.5cm
Activity 6 Six pieces of wood 20cm by 2.5cm long labelled as in diagram
Activity 7 A piece of wood 40cm by 5cm cut as in diagram
Notes
This is meant to be a circus activity. Students should be given the
questions one to answer before they begin the activities. Each glass tank
should have the instructions beside it.
Time
40 minutes to do the activities
Cost
Glass tanks £17 each if bought
£10 each if made
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Shapes for cutting wood for Activities 4, 5, and 7
Activity 4 15cm long and 9.5cm high
White Painted Wood =
Ice
Plain Wood = Crust
Activity 5 Crust 20cm long 5cm high, Ice 20cm long 3.5cm high
Activity 7 40cm long 4.5cm high
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SEA FLOOR SPREADING
Purpose
To work out what factors determine the amount of displacement of the
ridge along a transform fault.
To demonstrate the relationship between the movement of a continent
and the orientation of the ridge and the transform faults
Rules of motion
1. The spreading rates are the same on both sides of the ridge
2. Ridges are at right angles to the direction of motion
3. Transform faults are parallel to the direction of motion
Activity
1. Put the two pieces of card together as shown in diagram 1 and place a
piece of paper underneath. The card represents a continent which is
about to rift apart and the paper, when exposed, represents the
oceanic crust which is created.
2. Move the card pieces apart by about 4 cm as in diagram 2.
3. Mark the edges of the continent onto the paper using a brown crayon.
4. Draw a line joining points X and Y. The line shows the direction of
movement of the continents.
y
x
Diagram 1
Diagram 2
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5. Transform faults are always parallel to the direction of movement.
Draw in pencil a series of lines 2cm apart to represent the transform
faults. These should be between the continents and parallel to the line
joining X and Y. Mark the mid point of each line.
6. Use a red crayon to draw in the ridge on each block between pairs of
transform faults. It should always be at right angles to the transform
fault, and in the centre of the block it should be half way between the
continents.
7. Repeat instructions 1 to 6 using a new piece of paper but move the card
pieces in a different direction.
8. Look at a map of the Atlantic and suggest where the displacement
along the transform faults will be largest.
Teacher’s Section
Requirements
A4 cards (one for each student) cut to the pattern shown in the diagram.
Points X and Y are adjacent either side of the cut. Each student also
needs sheets of plain paper.
Map of Atlantic with out any transform faults shown.
Notes
Make sure students are drawing the ridge segments in correctly.
Results
Where the edge of the continent is at right angles to the direction of
movement there will be no offset but the amount of offset will
increase as the movement direction becomes more oblique to the
continents edge.
Time
30 minutes
Based on an article by Dennis Bates in the Journal of Geological Education 1990 v38
285
ACCRETIONARY PRISM
Purpose
To show how an accretionary prism is built up by thrusting at a subduction
zone and to show how the sequence of strata is formed.
In this activity the wooden blocks represent a continental plate and the
carpet represents an oceanic plate. The pieces of hardboard and the
cards represent layers of sediment with “a” being the oldest and “g” the
youngest.
Instructions
Activity I To show how an accretionary prism is built up.
1. Set up the apparatus as shown in the diagram
Cards
Wooden
Block
Strip of
Carpet
Bench
2. Place the hardboard pieces in a row on the piece of carpet.
3. Sketch the apparatus and describe it in geological terms.
4. Pull the carpet slowly down between the tables. Stop when the last
piece of hardboard has reached the subduction zone.
5. Describe what has happened and make a labelled sketch.
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Activity II To explain the sequence of strata found at accretionary
prisms
1. Set up the apparatus as shown in the diagram
2. Place seven pieces of the brightly coloured card labelled “a” side by
side along the strip of carpet to represent a layer of sediment.
3. Pull the carpet down until the card nearest the subduction zone begins
to tip.
4. Lay down all the cards labelled “b” on top of the “a” cards which are
still lying flat. These represent a new layer of sediment deposited on
top of the “a” layer.
5. Repeat instructions 3 and 4 with cards labelled “c, d, e, f, and g” until
all the cards have reached the subduction zone.
6. Describe what has happened in geological terms and make a labelled
sketch.
7. Draw a section or diagram to show the order of the beds in the
subduction zone. Mark the base of the card “a” as a thrust fault.
287
Teacher’s Section
Requirements
7 pieces of hardboard 10cm by 7.5cm.
Coloured cards 10cm by 7.5cm. There should be seven of a bright colour
labelled “a”. 6 of a different colour labelled “b” and 5 of another colour
labelled “c” etc up to “g”
2 wooden blocks 30cm by 10cm by 5cm one of which is nailed to a strip of
carpet 2.5m long and 10cm wide.
Two desks with a small gap between them.
Notes
This can be used as a class demonstration or for small groups of students
to play with.
If you only have a long bench the single block of wood can be placed on a
piece of L shaped plywood held onto the table with a G clamp.
Time
20 minutes
Results
This should result in a series of thrust slices each getting younger in the
direction of subduction but the slice with the youngest beds is at the
bottom. The sequence should be like this, (a is oldest bed, \=thrust, and
subducting plate is moving to the right).
abcdefg \ abcdef \ abcde \ abcd \ abc \ ab \ a
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METEORITE CRATERS
Purpose
To make a series of craters and to see what factors control their shape
and size. To compare these craters with those made by meteorites on
the earth and the moon.
Instructions
Examine and describe the features shown on the photographs.
To determine the effect of impact velocity
1. Level the surface of the sand by placing the strip of wood on the
edges of the tray and pulling it across the sand.
2. Hold the metre rule vertically beside the sand tray.
3. Choose a steel ball and weigh it.
4. Drop it from 25cm onto the sand.
5. Describe the shape of the crater.
6. Measure and record the diameter of the rim, the height of the rim
and the depth of the crater.
7. Calculate the impact velocity (v) using the formula v2 = 2 x 10 x
height in metres.
8. Calculate the kinetic energy on impact = ½ mass x v2
9. Repeat instructions 2 to 5 using the same steel ball but dropping it
from 50cm, then 75cm and then 100cm. Drop the ball so that it
lands in different part of the tray so that at the end you have 4
separate craters which you can compare.
To determine the effect of mass
1. Choose a steel ball and a marble of the same diameter.
2. Weigh them and the drop each from 1.0metre.
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3. Measure and compare the craters.
To determine the effect of size
1. Choose a marble and a steel ball of similar weights
2. Measure and record their diameters.
3. Drop them from 1.0 metre
To determine the effects of an increase in both size and mass
1. Choose steel balls of different sizes.
2. Drop them one by one from 1.0 metre.
3. Describe the
results.
Apparatus for simulating meteorite craters
290
Teacher’s Section
Requirements
Marbles and steel balls of various diameters upto about 25mm.
At least two trays at least 7cm deep and about 40cm by 30 cm. Smaller
trays will do but it is good to have several craters in the same tray to
compare.
12 litres of fine sand (¼ mm is suitable). This can be obtained from
building suppliers.
Photographs of craters.
Metre rule, setsquare
Callipers to measure diameters
Balance
Dropper and bowl of water.
Magnet and tweezers for plucking “meteorite” from the sand
Torch to show up shapes of craters
Notes
Crater depth and rim height are difficult to measure. It is interesting to
see how different students solve this problem. The crater depth can be
measured with a thin slice of a ruler or the edge cut off a grain size card
and a setsquare laid across the rim. Rim height can be measured using a
setsquare with millimetres marked on pressed into the sand.
Results
The craters increase in size with increasing velocity and density. A
marble and a steel ball of the same mass make a crater of the same size.
Rays, lines of ejecta leading radially away from the crater are a common
feature of real craters. The sand experiments do not make rays but they
can be made using flour.
The craters do not have hills in the centre as some real craters do. A
simulation can be made by dropping water into a bowl filled with water.
Time
1 hour if all activities are done
Cost
25mm steel ball £5 other steel balls about £1 each
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Appendix 1
Making glass tanks
Requirements
6mm glass with the following sizes:
base: internal length + 12mm x internal width + 12mm
sides: internal length + 12mm x height
ends: internal width x internal height
Aquarium sealant
2 rectangular wooden blocks 10cm x 10cm x 20cm or bricks
6 mm Glass
Internal Width
10cm
10 cm
Sides
Internal length + 12 mm x 10 cm
End Plate
10 cm x 10 cm
Base
Internal length + 12 mm x internal width +
12mm
1 Use corundum paper to round the edges of the glass so they are not
sharp.
2 Place the base on a flat surface.
3 Take one side and put a continuous bead of sealant along the lower
edge.
4 Place it on the back of the base. Press it down and support it with a
block.
5 Take each end piece in turn and put a bead of sealant along the bottom
and side edges.
6 Press each onto the base and against the side.
7 Take the second side piece and put sealant on the lower edge and place
it on the front of the base and against the ends. Support it with a block.
292
8 Make sure the sides are pressed together using two G clamps
9 Smooth out excess sealant along all joints on the inside using a wet
finger.
10 After it has hardened (24 hours) remove any excess sealant from the
outside using a knife. If there is any leakage put another bead of sealant
all around the inside and smooth it out.
For tanks longer than 50cm it is convenient to have a way of emptying the
water. Get a glazier to cut a hole large enough to take a 15mm tank
connector in the end plate. Assemble the pipe as shown in the diagram. Do
not solder the bend. Vaseline in the bend will prevent the water escaping
and will allow you to turn the end up to keep water in or down to empty.
End Plate 6mm Glass with hole to take
tank connector.
10 cm of 15 mm copper
tube
Soldered Joint
3 cm
90 bend. Not Soldered
only greased.
15mm tank
connector
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Making a pebbleometer (calipers for measuring the diameters of
pebbles)
fixed block
ruler screwed to
wood
sliding block
flange of plywood
Pebbleometer
Requirements
Strip of wood 38cm x 5cm x 2cm
2 blocks of wood 6cm by 6cm by 5cm
1 piece of plywood 5cm by 6cm
1 opaque 30cm ruler
2 4cm, 2 2cm and 3 1cm brass screws
1 Screw and glue one block onto the end of the strip of wood.
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2 Glue and screw the plywood onto the second block so that it over laps
it by 1cm.
3 Varnish all the wood
4 Carefully saw off the part of the ruler below 0cm.
5 Drill 3 countersunk holes into the ruler and screw the ruler to the
strip with the zero end tight against the fixed block.
To use place the pebble on the ruler and against the fixed block. Place
the second block on the ruler with the flange against the side of the
strip. Move the second block so that it touches the pebble.
Remove the pebble and read the measurement on the ruler at the edge of
the block.
Making a depth gauge
This is useful for measuring indentations such as the amplitude of ripple
marks or the anterior groove of echinoids.
Requirements
Tyre tread depth gauge
Piece of wood 20cm by 5cm by 2cm
Drill a hole in the centre of the piece of wood so that the tyre depth
tread gauge fits tightly into it and the bottom is flush with wood. The
tyre gauge should read zero when the wood is resting on a flat surface.
Angle measurer and depth gauge
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Making an angle measurer
This is easier to use than a protractor on its own.
Requirements
Protractor, wood 15cm by 2cm by 5mm,
clear plastic strip 10cm by 2cm with a line drawn down the centre.
3 small round headed screws, 1 washer.
Drill 3 holes in the bottom edge of the protractor one of which is in the
centre. Use the outer holes to screw the protractor to the wood. Screw
the plastic strip to the protractor and wood with the washer between the
plastic and the protractor.
Clear Plastic
Strip
Protractor
Screws
Wood
Support
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Tubes for permeability etc
Requirements for tubes
100ml plastic measuring cylinders or glass tubes
gauze 8cm square
Fernox leak sealant or similar
thin wire
The tubes are most easily made by cutting the bottom from 100ml plastic
measuring cylinder.
Put a bead of sealant all around the outside of the tube 1cm from the
bottom. Press the gauze on and around the bottom of the tube pushing it
into the sealant. Tie the wire around to hold the gauze in place.
Requirements for support
Board 18cm by 2cm thick. For length allow 10cm for every tube
Wood 3cm by 1.5cm by 80cm long cut into 2 pieces 25cm long and 2 pieces
15cm long
2 tool clips for each tube
The support should be made as shown in diagram and photo.
Diagram b and c
Measuring Cylinder
cylinder with
Measuring
or bottom cut off
or glass
tube
Glass
Tube
Sealant
Thin Wire
Gauze
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Board 18 cm High
2 cm Thick
tubes
Clips
At Least 5
cm
Supports
25 cm x 3 cm x
1.5 cm
Feet
15 cm x 3 cm x 1.5
cm at Right Angles
to Support
298
Tubes and rack
299
Appendix 2 Suggested topics for a full practical
report
Planning
Purpose
Background information
Hypothesis
Geological relevance
Variables and constants
Equipment
Safety
Method
Recording data
Number of measurements
Data
Data recording
A simple statement of why you are doing the work
One or two pages, You must include references and some
comment on their reliability.
The answers you expect to find with reasons. Refer to
your references.
Either economic or as a help to interpretation.
What you are hoping to vary and what you hope to keep
constant. Is it a fair test?
For each piece of equipment you must say why you are
using it and why you prefer it to alternatives
Comment on the safety aspects of the experiment you
plan. If none say so.
Describe with diagrams. Comment on the reliability and
expected accuracy. Say why you have chosen this over
other methods. Suggest how you will analyse your results.
Given an example of the chart you propose to use to
record your data on.
Say how many readings you will take and explain why you
have chosen that number
Say how many times you will repeat the experiment and
explain why.
You must record all your data clearly and systematically
so that it is comprehensible to anyone. You should hand in
the sheet on which you originally wrote down your
measurements
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Analysing
Tables summarising data
Graphs
Verbal conclusions
Explanation
Statistics or advanced
mathematical processes
Summary
Evaluation
General comments
Reliability
Accuracy
Table summarising data using simple maths e.g. averages,
ranges, modes
Draw graphs of your data. It is quite a good idea to give a
simple statement of what each graph shows underneath it.
Identify trends or patterns in your data. Compare your
results to those found in books.
Give scientific explanations for your results including any
anomalies. Refer to information found in your references.
Use statistics and gradients if relevant. Say why you have
chosen that particular form of statistics.
Clear short summary, 3 or 4 lines. Say whether
hypotheses have been proved or not.
e.g. easy/ difficult to set up, to take readings, to
understand, to use equipment correctly, enough time,
Are all your readings similar? Are your readings similar to
other students? If so your results are reliable.
Note any ways in which your readings may be inaccurate,
what are the main sources of error?
Anomalous results
Comment and explain any anomalous results. If there are
no anomalous results say so.
Suggested
improvements
Validity
Suggest improvements and give reasons
References
Is the experiment a reasonable simulation of a geological
process
Include lists of all books you have referred to and all web
sites and class notes. Give some indication of the
reliability of your sources
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Appendix 3 List of books and other sources
containing ideas for other experiments
Allen, JRL 1985 Experiments in physical sedimentology. Allen and Unwin
London
Bonnet RL and Keen GD 1990 Earth Science: 49 Science Fair projects.
McGraw- Hill New York
Carlson RC ? The catalyst collection outstanding earth science activities
Dept of Geological sciences California State university at Fullerton
Earth Science Curriculum Project 1967 Investigating the Earth Houghton
Miffin New York
Farndon J 1992 How the earth works. Eyewitness Dorling Kindersley
London
Heller RL 1962 Geology and Earth Sciences Sourcebook Holt Rinehart
and Winston New York
King C 1991 Sedimentology Book 1 and 2. Longman
National Curriculum Council 1993 Earth Science for Secondary School
Teachers National Curriculum Council York U.K.
Scotchmoor J and McKinney FK 1996 Learning from the fossil record
The Palaeontological Society
Tuke MF 1991 Earth Science: Activities and Demonstrations John
Murray London
Booklets
Earth Science Teachers Association has published a series of booklets
on different aspects of Geology entitled “Science of the Earth 11-14”
Each of which contains instructions for one or more experiments
designed for GCSE students.
Journals
Teaching Earth Science published by the Earth Science Teachers
Association (British)
Journal of Geological Education published by the National Association of
Teachers of Geology (American)
Many American publishers produce physical Geology lab books but they
only contain very simple or paper activities.
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Appendix 4 List of equipment
I have got most of my materials free by thinking ahead and collecting
when on holiday or fieldtrips (fieldtrips are particularly good because one
has porters to hand) and secondly by never passing skip by without
peering onto it especially if it is on a building site.
Aluminium shapes
Metal stores (see yellow pages) or engineering departments.
Anemometer
Scientific equipment suppliers e.g. Griffin and George
Callipers
These can be bought in hardware stores. Cheap ones are better than
expensive ones. Metal is better than plastic but do not get metal ones for
field work because they rust. For measuring pebbles see appendix 1
making equipment.
Concrete slabs
Garden centre or Building centre
Dinosaur models, to scale
Geology or natural history museums
Dice
Dice and games Ltd 01787 373501
Felt
Squares of felt (60cm by 60cm) can be bought from fabric/sewing shops
in a huge range of colours.
Fimo
Toy or modelling or art shops
Fishing line
This can be obtained from any sports shop, line to take the weight of 2kg
is sufficient.
Glass tubes
Laboratory suppliers see yellow pages
303
Glass tank
Glaziers will make them for you (see appendix 1)
Grain size scales
These can be bought very cheaply from Geosupplies 16 Station Rd,
Chapeltown, Sheffield S30 4XH.
Guttering
Flat bottomed guttering can be bought in 2 or 3m lengths from builders
merchants
Hair dryers
These are used as a source of wind. Buy them from car boot sales or
steal them from your wife or daughters when they upgrade.
Microscope, pocket x30 or binocular
Geosupplies, 16 Station Rd Chapeltown, Sheffield, SO30 4XH
Minerals
See under rock samples.
Plastic tubing
Clear flexible plastic tubing in a variety of internal diameters can be
obtained from hardware stores.
For clear rigid plastic tubing see yellow pages under plastic engineering
materials. Acrylic extruded is cheapest.
Restistivity meter
Damp tester from hardware shop
Rock samples
If not available in the lab then they can be obtained from
Richard Taylor, Byways, 20 Burstead Close, Cobham, Surrey KT11 2NL
01932 62340
Rock Slabs
These can usually be obtained free of charge from stone masons.
University departments usually have a large rock saw and might be willing
to cut a limited number of rocks.
304
Rubber sheet
Hardware stores have a variety of thicknesses, usually in metre wide rolls
Sand and pebbles
Builders Merchants sell a variety of sands in 25kg bags: sharp sand is
course and poorly sorted, mortar sand is finer and the finest is sand used
for brushing over pavoirs. Bought sand needs washing unless it is sold as
silver sand.
Bags of pebbles can also be bought from a builders merchants but a
greater selection can be found at some garden centres.
Sand and pebbles can, of course, be obtained from the seaside or from
quarries and rivers.
Sieves
Endecotts Ltd 9 Lombard Rd London SW19 3TZ or Geosupplies 16 Station
Rd, Chapeltown, Sheffield S30 4XH
Sponge Rubber
This can be ordered from some furniture stores or over the internet or
in most cities there will be a place where they will cut it for you.
Steel Balls
See yellow pages under bearings
Steel cylinders and rods
See yellow pages under steel fabrications
Tyre tread depth gauge
Car shop such as Halfords
Trays
Garden centres often have a large range of tray sizes
305
APPENDIX 5
Equipment available in the lab
It is prudent to have the following equipment available in the lab because
it is often needed and students do not always bring the equipment they
are supposed to.
Protractors
Compasses (for drawing circles)
Calculators
Scissors
Rulers
Hand lenses
Grain size cards
Brush and pan for spilled sand etc
Cloth for spilled water
Appendix 6 References
Collis L and Fox R A 1985 Aggregates Geological Society London
Hall A 1987 Igneous Petrology Longman London
Gribble C D 1988 Rutley’s Elements of mineralogy Unwin London
Kennet P and Ross CA 1983 Geochronology. Longman York
Kennet P and Ross CA 1983 Palaeoecology. Longman York
Lipman PW and Mullineaux DR 1981 The 1980 eruption of Mount St.
Helens United States Geological Survey Prof Paper 1250
British Fossils 1975 British Museum Natural History London
Roberts R L 1993 Field Guide to Geological Structures. Macmillan London
Thulborn T 1990 Dinosaur tracks. Chapman and Hall London
Weiss L E 1972 The minor structures of deformed rocks. SpringerVerlag
New York
Waltham A C 1989 Ground subsidence Blackie London
Appendix 7 Photocopying rock slices
In many cases it is advantageous for students to have photocopies of
rock slices because these can be marked. It is usually helpful to have the
original rock slice for students to see.
Take a piece of A3 paper and put the slice on it and mark around the
outside of the slice. Now cut out the shape of the slice.
First place a sheet of acetate (overhead transparency) on the
photocopier and then the paper on top. Place the slice within the hole in
the paper. If you can choose between text or photo on the machine
choose the latter. Now you are ready to photocopy. Adjusting the
darkness may improve the copy.
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About the author
Mike Tuke has spent the last 35 years teaching A level Geology, first at
Hinchingbrooke Comprehensive School in Huntingdon, then at Cambridge
College of Arts and Technology (now Anglia Polytechnic University) and
lastly at Cambridge Regional College. He now teaches part time at
Netherhall School, Cambridge. In addition to teaching A level, for many
years he taught mature students coming back into education on Access to
Higher Education courses. He has also taught degree students and for 15
years he gave training days to PGCE students at the University of
Cambridge and was part of the teacher training department at Cambridge
Regional College.
Mike has written a book on practical activities for Key stage 3 and a
pamphlet for Key stage 2, as well as many articles in Teaching Earth
Science and its predecessor Teaching Geology. He is also one of the
authors of the A level textbook “Geoscience”
For 11 years Mike was a moderator for coursework for OCR.
Mike’s academic interests include developing visual aids, demonstrations
and activities for teaching geology.
Mike is married and has two grown up daughters. He enjoys renovating his
old farm house, bee keeping and hill walking.
307