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Eyjabakkajökull
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V
www.need.is
www.geoneed.org
Öxi
A
Axarfellsjökull
S
Skeiðarárjökull
Þrándarjökull
Hofsjökull
Vatnajökull
Berufjörður
Skaftafellsjökull
Búlandstindur
9
Lónsöræfi
Skaftafell
1
Skeiðarársandur
Öræfajökull
Öræfi
Fallastakkanöf
2
Breiðamerkurjökull
3
Háalda
Jökulsárlón
Hornafjarðarfljót
Jökulsá
Baulutjörn
6
Mýrar
13
Publisher: Hornafjörður Rural Research Centre. Text and translation: Sigrún Inga Sigurgeirsdóttir, Helga Davids, Þorvarður Árnason.
Design and layout: Náttúrulega ehf. Cover picture: Sigrún Inga Sigurgeirsdóttir. Printing: Prentmet ehf.
Þvottá
Lón
Almannaskarð
Skarðsfjörður
Melatangi
Álftafjörður
Díma
Nes
Höfn
- 30 km -
Gatklettur
11
Hornafjörður
Kvíármýrarkambur
Ingólfshöfði
16
Djúpivogur
Suðursveit
4
Blábjörg
15
Hofsdalur
5
Hvannadalshnjúkur
Fjallsá
Rauðaskriða
8
7
18
Teigarhorn
Heinaberg
Hjallanes
Kálfafellsdalur
14
Fláajökull
Skálafellsjökull
Svínafellsjökull
17
Jökulgilstindar
Hoffellsjökull
Esjufjöll
12
Hvalnes
10
Vestrahorn
Stokksnes
Papey
Berunes
1
Skeiðarársandur
Skeiðarársandur is a glacial
outwash plain (sandur)
formed of sediments deposited by rivers flowing from the
S k e i ð a r á r j ö k u l l g l a c i e r.
Skeiðarársandur is the largest
outwash plain in Iceland, covering an area of ca. 1000 km2.
Photo: Regína Hreinsdóttir
It is the largest glacial
outwash plain of Europe. Sediments in outwash plains are
often size-sorted by the water. Larger boulders are deposited close to the margin of the glacier, gravel further away
from it and the finest sediments, sand and clay, are deposited close to the sea. Jökulhlaup (glacial outburst floods),
glacier retreat and glacier advance have created a great
variety of fluvioglacial landforms in front of the glacier, like
kettle holes. The outwash plain is still being shaped by ice
and water and there, one has a good opportunity to see
glacial and fluvial land-forming processes at work.
7
Heinaberg
In the Heinaberg area, various
landforms can be found that
have been created by the
action of glaciers and the sea.
When Heinabergsjökull glacier
reached its point of maximum
advance , its sno ut blo cke d
Photo: Rannveig Einarsdóttir
Heinabergsdalur valley, forming
lake Dalvatn. In the middle of the slopes of
Heinabergsdalur, several ancient shorelines can be seen,
that indicate various water levels of the former icedammed lake. Heinabergsjökull also blocked another side
valley, Vatnsdalur and as a result, water collected there,
forming a lake that drained in cathastrophic annual floods
In the remote past, some of the rocky hills in the
Heinaberg area were surrounded by the ocean, which
accounts for the wave cut cliffs found on the seaward side
of the hills. Another interesting geological feature in the
area is Heinar, a rock formation with beautiful basalt columns.
13
Þvottá
Along the shoreline close to Þvottá river, ignimbrite can be
found, a volcanic rock that forms by the welding together
of tuff from an explosive volcanic eruption. Several dikes
can be found as well and
one of them has eroded in a
very special way. Dikes are
a characteristic feature of
the landscape around Þvottá.
Dikes are thin rock layers
which have solidified in
factures. They are usually at
r i g h t a n g l e s t o t h e s u rPhoto: Andrés Skúlason
rounding rock layers. In Iceland, dikes are most common in
the Tertiary Basalt Formation, which forms about 80% of
the bedrock in East Iceland. The dikes at Þvottá are variable in size, some of them small and thin, but others form
high walls. At Þvottá, many types of metals have been
found, in very small amounts, e.g. gold, silver, mercury and
platina.
2
Öræfajökull
Öræfajökull is a stratovolcano at the southern edge of the
Vatnajökull ice cap, with a
large ice-filled caldera. The
volcano is located on the
Öræfajökull flank zone, a
volcanic belt that is not
very active. Öræfajökull is
the second largest volcano
in Europe; its base covers
Photo: Þorvarður Árnason
an area of ca. 400 km 2
and its volume is close to 370 km2. Öræfajökull is an active
volcano that erupted 5-6 times before the settlement of
Iceland. It has erupted twice during historical times, in
1362 and 1727. During the first eruption, the volcano
ejected a huge amount of tephra and farms and pastures in
the neighboring district were destroyed either by tephra fall
or by flooding. Hvannadalshnjúkur (2.110 m)on the northwestern rim of Öræfajökull is the highest peak of Iceland.
8
Fláajökull
The landscape in front of
Fláajökull glacier is newly
exposed and still being shaped
by ice and water. In this area
several hiking trails have been
ma r ke d, a mo ng o the r s a n
educational trail with information about the uneasy coexisPhoto: Rannveig Einarsdóttir
tence between man and
nature in the old days, before the construction of the flood
protection dikes. In 1937, such dikes were built close to the
glacier, in order to protect the farmlands against flooding
by glacial rivers. The dikes were constructed in a fairly
primitive manner, using only hand tools and horse power.
Fláajökull has retreated more than 2 km in the last 100
years and about 20 km2 of new land has been exposed.
The moraines in front of the glacier contain remains of tree
trunks, indicating that the glacier has advanced over land
covered by forest during the period of the settlement.
14
Rauðaskriða
In the middle of Mt.
Hálsafjall is a rhyolite scree
slope, a very prominent feature of the landscape
because of its reddish colour.
This scree slope is called
Rauðaskriða, which means
“red scree”. Rhyolite is an
acid volcanic rock, which is
Photo: Sigrún Inga Sigurgeirsdóttir
usually very colourful. Above Rauðaskriða, there is a ledge
in the mountainside, which is called Rauðuskriðuhjalli. Likely, Rauðaskriða has its origin in the extinct Álftafjörður central volcano, which was active around 10 million years ago.
Its activity lasted for about 500.000 years, but in the end,
it got buried under basalt lava flows from fissure eruptions.
Before, Rauðuskriða was quarried and rhyolite slabs from
the scree slope were e.g. used as wall cladding on buildings.
Nowadays, Rauðaskriða is protected and quarrying is no
longer allowed.
3
Háalda
Háalda is a bulky fluvioglacial sediment ridge, formed during a glacial burst
(jökulhlaup) that followed
the 1727 eruption of
Öræfajökull. In the wake of
the eruption, a huge flood
rushed down the Kotá river,
carrying blocks of ice from
Kotárjökull glacier to the
alluvial plains below. The
Photo: Helga Davids
icebergs became buried by
sediments and as they melted, they left large depressions
in the Háalda ridge, so-called kettle holes. Kettle holes can
also form when glaciers retreat and advance. Usually the
depressions get filled with water and become kettle lakes,
but they can also stay dry. Blocks of ice that break off glaciers or are carried down during floods are often called
“dead ice” and the landscape at Háalda with its kettle holes
is a typical dead ice landscape.
9
Hoffellsjökull
During the 17th century, the climate detoriated significantly
and several outlet glaciers of
Vatnajökull, like Hoffellsjökull,
advanced into the lowland
areas. Hoffellsjökull is now
one of the largest outlet glacie r s de sce nding fr o m the
southern margin of Vatnajökull.
The glacier reached its maxiPhoto: Þorvarður Árnason
mum extent shortly before
1900 AD and at that time, it loomed over the terminal
moraine in front of it, but in recent decades it has retreated
very quickly. As the glacier retreated, a lagoon formed in
the depression carved by the glacier and expanded rapidly.
Fossils of marine animals have been found in the moraines
in front of Hoffellsjökull, indicating that the glacier has
overridden ancient marine sediments. Research on
Hoffellsjökull goes back a long way. In this respect, it is
worth mentioning the 1936 expedition lead by Jón
Eyþórsson and the Swedish scientist Hans Ahlmann.
15
Gatklettur
In Hálsaskógur forest,
interesting geological
features can be found,
e.g. many bizarre lava
formationsandGatklettur,
a rock formation with two
parallel holes in it. The
holes are casts of ancient
trees and are considered
to be a certain kind of
Photo: Andrés Skúlason
fossil.They form when hot lava flows over a forested area.
The lava flows up against tree trunks and knocks some
down. The trees then burn, but in the process the lava
cools and hardens around the trunks and, in the end, the
burned trees leave holes in the lava. In Hálsaskógur, the
holes are horizontal, indicating that the trees fell down
when the lava flowed over the area. The bedrock at
Gatklettur dates from the Late Miocene (8,5-10 million
years ago).
4
Kvíármýrarkambur
The end moraines at
Kv í a r m ý ra r k a m b u r a r e
among the largest and most
magnificent in Iceland. The
Kvíármýrarkambur moraine
reaches 173 m above sea
level and is believed to have
formed ca. 2500 years ago.
Kvíármýrarkambur is a comPhoto: Regína Hreinsdóttir
posite moraine ridge, mainly c o ns is ting o f de br is , fa lle n o r pluc ke d fr o m the
mountainsides, carried down by Kvíárjökull glacier and
eventually deposited at its snout. The glacier reached its
maximum extent around 1900 AD when the snout of the
glacier rose high above the moraine, so that ice blocks now
and then broke off the glacier and rolled down the outer
slopes of the moraine. Since then the glacier has retreated
considerably. Kvíármýrarkambur has been registered as a
natural history site that deserves protection.
10
Vestrahorn
The oldest rocks of Southeast Iceland can be found in
Vestrahorn (and Eystrahorn); lava flows and rhyolites that
are around 8-10
million years old.
Glacial erosion
has removed the
upper 2 km of
extrusive rocks
and exposed
Photo: Þorvarður Árnason
deeper intrusions,
e.g. the large pluton that forms the core of the extinct central volcano of Vestrahorn. This pluton represents the
uppermost part of an ancient magma chamber and consists
mainly of gabbro, but contains also granophyre. These are
intrusive plutonic rocks that solidify at considerable depth
beneath the earth´s surface and cool slowly. Under these
circumstances, rocks become coarsely crystalline and very
hard and can therefore withstand weathering better than
16
Teigarhorn
Te igar ho r n is o ne o f the
most reknown sites in the
world where zeolites are
found. Zeolites are certain
type s of amygdule s that
occur in crags and wave cut
cliffs and become visible
when the surrounding rocks
erode. Amygdules are
Photo: Andrés Skúlason
formed at great depth under the earth´s surface and only
become visible under special circumstances. It is believed
that at Mt.Teigarhorn, a ca. 1500 m thick layer of rocks
that was lying on top of the Tertiary Basalt Formation in
which the amygdules occur, has eroded away. Moreover,
the land has risen because of isostatic movements of the
crust and therefore, the amygdules can now be found at
the surface. Teigarhorn is protected as a natural monument
and it is not allowed to damage the geological formations in
the area.
5
Fallastakkanöf
One of the most beautiful
examples of basalt columns in
Iceland can be found at
Fallastakkanöf. The basalt columns at Fallastakkanöf are ca.
90 m long and are considered
to be among the highest in
the country. Basalt columns
Photo: Helga Davids
form when basaltic magma
cools gradually and contracts, causing polygonal (often
hexagonal) cracks to develop. Basalt columns always form
at a right angle to the cooling surface and are thus vertical
in lava flows and sills. Fallastakkanöf is a cliff at the southern edge of Hestgerðishnúta. The upper part of
Hestgerðishnúta is made of palagonite (tuff), which probably formed under a glacier during a subglacial eruption.
Subsequently, the palagonite was washed away by a large
glacial outburst flood and filled a glacially eroded valley.
The name Fallastakkanöf refers to the gular poach of a
whale.
11
Díma
Díma is a skerry on
the outwash plains of
the river Jökulsá í Lóni.
It is obvious that Díma
has been an island for
quite a long time.
Almost the entire
skerry is surrounded
Photo: Árnína Guðjónsdóttir
by s he e r c lif f s tha t
show distinct signs of fluvial (and glacial) erosion. Only at
the northwestern side of Díma, the slope is gentle and
there a sheep track starts, that leads to the top of the hill.
Nowadays, the main course of the river lies east of Díma.
From the highest point of Díma there is a good view of the
outwash plains of the river Jökulsá and the mountains of
Stafafellsfjöll. In the Stafafellsfjöll mountains, various interesting geological features can be seen, e.g. colourful rhyolite scree slopes, extinct central volcanoes and landscapes
that are heavily eroded by glaciers and rivers.
17
Búlandstindur
Búlandstindur (1069
m) is the highest
mountain in Iceland
which rises directly
from the sea. It is
believed that the formation of the mountain started around 8
million years ago. It is
a typical example of a
mountain made of
Photo: Elísabet Guðmundsdóttir
Tertiary Basalt, consisting of dozens of basalt layers, piled
up on top of each other. Búlandstindur has been shaped by
erosion and has sharp edges and straight lines. The mountain got its present appearance when it rose above the
Pleistocene ice sheet and outlet glaciers scoured the peak
from both sides. The mountain is beautifully shaped, like a
pyramid. It is quite popular, but challenging, to climb the
peak.
6
Hjallanes
Around the turn of the 20th century, Skálafellsjökull glacier
advanced over Hjallanes, leaving various traces of its presence on the terrain, like lateral moraines, “sheepback
rocks” (or roches moutonnées), erratics and glacial striations. Lateral moraines are
ridges of debris deposited
along the sides of a glacier.
Rock formations in the path of
a glacier become rounded and
elongated and are therefore
referred to as “sheepback
rocks”. Erratics are boulders
Photo: Rannveig Einarsdóttir
that don´t originate from the
place where they are found, but have been transported
there by a glacier. Glacial striations are long, straight lines
in the bedrock, formed by debris embedded in the base of
an advancing glacier. A hiking trail has been marked on
Hjallanes and interpretive signs provide information about
key points of interest along the trail.
12
Hvalnes
From Hvalnes, there is an excellent view of the long and
curved beach ridge that closes off Lónsfjörður and of the
impressive mountains to the north. The farm Hvalnes lies at
the foot of the precipitous mountain Eystahorn, also known
as Hvalneshorn. Eystrahorn is considered to be the upper
part of an ancient magma chamber, like Vestrahorn. Originally, this magma chamber
was situated at a depth of ca.
1-2 km under the surface of
the earth, but was revealed
after the overlying rocks had
b e e n e r o d e d a w a y. T h e
magma chamber is represented by an intrusion of
g a b b r o a n d g ra n o p hy r e ,
Photo: Þorvarður Árnason
which is rather smaller than
the intrusion at Mt. Vestrahorn. Small amounts of gold, silver, mercury, titan and other metals were discovered in the
intrusion. Sand dunes are a prominent feature of the landscape around Hvalnes.
18
Blábjörg
In Berufjörður, bluegreen
ignimbrite can be found.
It occcurs in a prominent
layer that can be followed
along the mountainside
and down into the sea.
Ignimbrite is an acid rock
type, consisting mostly of
ash, pumice and lapilli,
Photo: Andrés Skúlason
that are welded together.
Ignimbrite is formed when a pyroclastic flow (also known
as a nuée ardente) sweeps down the flanks of a mountain
during an explosive volcanic eruption. A sea cliff called
Blábjörg (“the blue cliff”) is part of this peculiar and extensive ignimbrite layer. The landscape along the sea shore at
Blábjörg is interesting and diverse, e.g. the rock formation
Gatklettur, a sizable natural rock arch, resting on three pillars and surrounded by the sea.
Geo-sites in Southeast Iceland