bryce canyon national park

DISCOVERING THE MYSTERIES OF
BRYCE CANYON NATIONAL PARK
The Colorado Plateau - Grand Staircase Stepping Through Time
Grade Level: 4th-8th grades
Subject Area: Earth Science
Objectives:
Introduce students to the concept of the Grand
Staircase and the geographical location of
different parks along that staircase.
Emphasize that different layers were formed by
unique past environments and the rocks and fossil
records tell us what that the environment was like.
Teach students about the specific environments
that created each layer of the Grand Staircase.
method:
Using the Internet for information, students will
research the Grand Staircase and learn its unique
geological features. Students will also learn about
the paleogeographic depositional environments for
rocks found in the Grand Staircase before considering
present day locations that are similar. Students will
have an opportunity to view images of geologically
significant features of the Grand Staircase and their
geographic distribution.
background:
The Grand Staircase includes regions of Utah, Arizona
and Colorado from the Grand Canyon to Bryce
Canyon. In the 1870s, geologist Clarence Dutton
first conceptualized this region as a grand stairway
ascending from the north rim of the Grand Canyon
in the south and continuing northward over a series
of south-facing steps ranging from 500-1000 meters
high. The Grand Staircase is a series of nearly
flat-lying sedimentary rocks with the oldest being
exposed in the Grand Canyon and progressively
younger rocks being exposed with each step up to
the north. From the Grand Canyon northward to
Bryce Canyon the Dutton divided this layer cake
of Earth’s history into five steps that he colorfully
named Pink Cliffs, Grey Cliffs, White Cliffs, Vermilion
Cliffs, and Chocolate Cliffs. The sequence of cliffs
and terraces making up the steps are composed
of erosion resistant rocks, such as limestone and
sandstone, while the slopes and flat areas are
composed of less erosion resistant rocks, such as
shale and siltstone.
What makes the Grand Staircase unique is that it
preserves more of Earth’s history than any other
single place on Earth. Geologists often liken the
study of sedimentary rock layers to reading a history
book---layer by layer, detailed chapter by chapter,
Earth’s history is written in the rocks. The problem
is that in most places in the world, the book has
missing pages and chapters as a result of erosion.
But, the Grand Staircase and the lower cliffs of the
Grand Canyon remain a largely intact sequence
of over 600 million years of rocks with only a few
paragraphs missing.
The Pink Cliffs are part of the Claron Formation
which makes up the hoodoos observed at Bryce
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DISCOVERING THE MYSTERIES OF
BRYCE CANYON NATIONAL PARK
The Colorado Plateau - Grand Staircase Stepping Through Time
Canyon National Park. They are the youngest of
the rocks, about 50 million years old, in the grand
Staircase. These pink and white limestones were
deposited during the Cretaceous through the
Pliocene time periods when the region was covered
by a shallow sea. Mixed in with the limestones
are fine-grained sandstones and mudstones. The
mudstones play a special role in the formation and
appearance of the hoodoos. Water erodes the
mudstones causing them to flow down over the
limestone layers coating the exterior of the hoodoos
with a stucco-like covering of clay.
The Gray Cliffs are composed of gray to nearly black
rocks of the Dakota formation. These rocks include
mudstones, coal, shale and sandstones. Dakota
formation rocks are Cretaceous in age, having been
deposited around 95 million years ago. The Dakota
sandstone is a widespread unit that can be seen in
many locations in the western United States. In the
Grand Staircase it forms cliffs that stand out from
the White cliffs below it and pink cliffs above. The
sediments forming the rocks in the Dakota formation
were deposited in shallow warm seas and near shore
swamps that were probably similar to the present day
coastal regions of Florida and Louisiana.
The White Cliffs are predominantly Navajo
Sandstones. These sandstones commonly exhibit
cross bedding formed by winds. At the time these
Pink Cliffs
Gray Cliffs
White Cliffs
Vermillion Cliffs
Chocolate Cliffs
The Grand Staircase as seen from the LeFevre
Overlook in the Kaibab National Forest
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DISCOVERING THE MYSTERIES OF
BRYCE CANYON NATIONAL PARK
The Colorado Plateau - Grand Staircase Stepping Through Time
Procedure:
sands were being deposited the region was covered
by great desert similar to the present day Sahara.
Navajo sandstones were deposited around 185
million years ago during the Jurassic period. Cliffs
formed by this sandstone are extremely resistant
to erosion, as evidenced by their towering heights
sometimes reaching 1500 feet.
The Vermillion Cliffs are part of the Kayenta and
Moenave formations deposited around 200 million
years ago. These formations consist of sandstones,
shales and siltstones formed from sediments
deposited in streams and lakes that flowed over or
covered savannas similar to those found in modern
day Kenya. The Kayenta formation contains dinosaur
foot prints.
The Chocolate Cliffs is composed of the Chinle and
Moenkopi formations which were deposited around
210 -245 million years ago. The Chinle contains the
world famous Petrified Forest. It is also well known
for badlands deposits and ash deposits from nearby
volcanoes. The Moenkopi formation is made up of
limestone, shale, siltstone and sandstone. These
sediments were deposited in coastal tidal flats as
the shallow sea shoreline drifted back and forth in
the region during the Triassic time period. The rocks
of the Moenkopi formation are rich in ripple marks,
mud cracks, reptile and amphibian tracks and shallow
water marine fossils.
materials:
Google Earth
Grand Staircase flash cards
Internet access to view paleogeographic
maps
Data sheet for the Grand Staircase
1. Use Google Earth to locate Bryce Canyon National
Park and the North Rim of the Grand Canyon
National Park. Make sure students can recognize this
region on a map from the outline of the states.
2. Review the descriptions of the rock types found at
each “step” on the Grand Staircase using the “step”
flash cards. Record this information in the data sheet.
3. Students should draw an arrow from each “step”
name to the “step” on the final flash card.
4. Compare what you know about the rock types
found at each step with the Triassic, Jurassic, and
Cretaceous maps. See the links below for access to
maps showing what conditions were in the Colorado
Plateau region during the time period when each of
the sedimentary formations was being deposited.
5. Look for the region that would be the present
day location of the Grand Staircase. Determine what
type of environment was present during this time
period. This is the depositional environment for the
sediments that are preserved in the rock record.
Record this information in the data sheet.
6. Correlate the rock types and features to the
environment. Discuss what types of environments
produce each type of sediments. For example, the
sandstone observed in the heavily cross bedded
Navajo sandstone deposits formed in a desert as
wind blow sand grains into sand dunes. These
dunes were later preserved in the rock record as
cross bedded sandstones.
7. Identify a present day location where a similar
environment exists. Use Google Earth to search for
locations around the globe where the environment
today is similar to the environment at the time
the sediments were deposited. Students could
even make a Google earth tour to demonstrate
their understanding of the correlation between
depositional environment, sediment and
sedimentary rock type.
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DISCOVERING THE MYSTERIES OF
BRYCE CANYON NATIONAL PARK
The Colorado Plateau - Grand Staircase Stepping Through Time
Flash cards:
Flash cards for each of the “steps” should be printed
out to be used during the class. One set of flash
cards per small group of students (3 or 4). For best
results print flash cards on colored card stock paper.
You might want to laminate these for future use.
Paleogeographic maps:
Click on the link to view each map. Maps courtesy
of Ron Blakey, Professor Emeritus, Northern Arizona
University.
Pink Cliffs – 50 mya:
http://tinyurl.com/pinkcliffs
Gray Cliffs – 95 mya
http://tinyurl.com/graycliffs
White Cliffs – 185 mya
http://tinyurl.com/whtcliffs
Vermillion Cliffs – 200 mya
http://tinyurl.com/vermcliffs
Chocolate Cliffs – 210-245 mya
http://tinyurl.com/chococliffs
references:
Extension activities:
Students have started to build a regional
stratigraphic column. They could continue to
work with older materials by investigating the
ages, formations and rock types exposed in the
Grand Canyon. Students could make a poster,
PowerPoint , Glogster or other presentation
showing the full stratigraphic column for the
region.
Use Google Earth to create a tour of the Grand
Staircase. Add in the Grand Canyon. Students
could add images at locations where there are
exposures of each rock formation.
Images – Ron Blakey, Northern Arizona
University
The Grand Staircase cross section
http://jan.ucc.nau.edu/~rcb7/Grand_
Staircase_topo.jpg
Paleogeographic maps Ron Blakey, Professor Emeritus, Northern
Arizona University.
The National Park Foundation is the national charitable
partner of the National Park Service.
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DISCOVERING THE MYSTERIES OF
BRYCE CANYON NATIONAL PARK
The Colorado Plateau - Grand Staircase Stepping Through Time
The Grand Staircase – Data Sheet
Time period /
Cliff type
Rock
formation(s)
Rock types
present
Special features
Depositional
environment
Present day
location
5
Pink Cliffs
Gray Cliffs
Claron Formation
pink limestone
white limestone
mudstone
fine-grained sandstone
50,000,000 years old
hoodoos
Dakota Formation
mudstone
shale
coal
sandstone
95,000,000 years old
White Cliffs
Vermillion
Cliffs
Navajo Sandstone
sandstone
cross bedding
185,000,000 years old
Kayenta Formation
Moenave Formation
sandstone
shale
siltstone
200,000,000 years old
Chocolate
Cliffs
Chinle Formation
Moenkopi Formation
limestone
sandstone
shale, siltstone
210,000,000 –
245,000,000 years old
Pink Cliffs
Gray Cliffs
White Cliffs
Vermillion Cliffs
Chocolate Cliffs