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LoFF

Karsten Piepjohn, Rolf Stange,

Malte Jochmann & Christiaane Hübner

With excursions in and

around Longyearbyen!

of Longyearbyen

The Geology

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Svalbard tells a fantastic history through the seemingly unremarkable rocks of the dark-shaded mountain ranges that lie exposed beside the glaciers and along the cold coasts. Geological history is excellently presented, as if in a geology textbook, because the ice-free areas are not

covered by vegetation the way they are in Central Europe, for example. A large proportion of Earth’s history is exposed on the islands of the small archipelago, which makes Svalbard uniquely attractive to geologists in the Arctic.

Publisher: Longyearbyen feltbiologiske forening (LoFF)P.O.Box 694, 9171 Longyearbyen

All text, figures, maps and photographs, unless otherwise specified, are by Karsten Piepjohn, Malte Jochmann, Rolf Stange and Christiaane HübnerIllustrations and layout: Trond HaugskottTranslation: Janet Holmén

Map: Geology of Svalbard (Hjelle 1993).

Introduction

2012 ©

No. of pages: 36Issue: 1000

ISBN 978-82-93009-05-4 (printed)ISBN 978-82-93009-06-1 (PDF)

The present landscape shows distinct land forms characteristic of cold climate conditions on Earth: in Longyearbyen, the Quaternary Ice Age still has not ended. In this booklet, we would like to take you on an exciting journey through the ancient past in the surroundings of Longyearbyen. We will start with a brief general description of Svalbard’s geological history, and then zoom in on the geology and the present landscape in and around Longyearbyen.

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The rocks of Svalbard represent a huge archive of information about geological history, the ancient climate, earlier life forms and the evolution of Svalbard through space and time. Incredible as it seems, Svalbard was covered by tropical oceans, deserts or subtropical

rain forests eons ago. The current apparently stable geographic position at the north edge of the European continent is the result of a long journey from the South Pole to the North Pole over the last 600 million years. How many are aware that Svalbard was situated at the center of a huge ancient continent (called Laurasia) which unified North America, North Europe and Asia for more than 300 million years? It sounds like science fiction – but, in contrast to H.G. Wells’ novel, geology really is a kind of a time machine... Some 600 million years ago, the landscape of Svalbard was dominated by large glaciers of an ancient Ice Age. The big difference: Svalbard was not located in the northern hemisphere of the old Earth but in the vicinity of the South Pole! Since then, Svalbard has drifted northward 12,000 kilometers through our planet’s various climate zones, approaching its present position at a «speed» of 2.5 centimeters per year!

1 The geological history of Svalbard – a journey through time and space

In Devonian times, Svalbard crossed the Equator, and a huge desert dominated the landscape, which probably looked like the Sahara in southwest Libya today. It’s almost unbelievable, but rain shower that took place 400 million years ago in the Devonian desert left imprints that can still be seen at Woodfjorden!

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1 The geological history of Svalbard – a journey through time and space

By the end of the Devonian, the climate became more humid: the oldest forests on Earth grew along the shores of ancient rivers in what is now Dickson Land west of the Russian settlement of Pyramiden.

At the beginning of the Carboniferous, some 350 million years ago, Svalbard was located in the northern Tropics. As in Central America today, huge rain forests covered parts of the island, which turned later into the coal that was mined in Pyramiden until 1998.

In the middle of the Carboniferous (330 million years ago), Svalbard was inundated by a shallow, subtropical sea. Numerous marine fossils such as corals indicate that Svalbard was situated at a geographical latitude similar to that of the Bahamas today. This warm shallow sea covered wide areas of the present arctic until the end of the Permian.

Fossil corals in life position at Brøggerhalvøya.

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During the Triassic and Jurassic, 250 to 150 million years before present, Svalbard travelled continuously northwards into the humid climate zone of the Earth. It was still covered by a shallow sea, but the water was colder than in the sub-tropical seas of the Carboniferous and Permian. Life was dominated by ammonites and huge marine dinosaurs such as ichthyosaurs and plesiosaurs. During Lower Cretaceous times (150-100 million years ago), the shallow sea disappeared, and Svalbard emerged as land where dinosaurs several meters tall, such as Iguanodon, grazed in the Cretaceous forests. By the beginning of the Tertiary some 65 million years ago, Svalbard had already reached its present geographical latitude. The island was characterized by extensive humid forests similar to the present forests in Central Europe. If it were possible to travel back to Svalbard of 65 million years ago, we would find the vegetation very familiar. How strange to think that the dinosaurs had just died out at that time! Forty million years ago, the climate worldwide started to cool down and about 3 million years ago, the present Quaternary Ice Age started in the northern hemisphere. The landscape of Svalbard became what we see today.

Ichthyosaurus at Kapp Thordsen (Photo: Dierk Blomeier).

Ammonite from Ostrogradskij­fjella, Hornsund.

Plesiosaurus

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The pearl necklace of mines in Longyeardalen (from left to right): Gruve 1B at Sverdrupbyen (180 masl), Gruve 1A above the church (240 masl), the mine at Hiorthfjellet (550 masl), Gruve 2B at Sukkertoppen (270 masl), Gruve 2B above Nybyen (230 masl) and another mine opening to Gruve 2B close to Larsbreen. Picture taken from the entrance of Gruve 4 (just below Sarkofagen at 160 masl).

The geology of Longyearbyen and its surroundings is dominated by marine and terrestrial mudstones and

sandstones of the youngest chapters of Earth’s history. Looking from Longyearbyen across Adventfjorden at Hiorthfjellet, you can see an almost horizontal succession of Cretaceous and Tertiary sedimentary beds with the oldest rock units at the bottom and the youngest deposits on top. The lower and middle parts of Hiorthfjellet consist of 140-100 million-year-old deposits of the Early Cretaceous era, whereas the upper third of Hiorthfjellet is formed of 65-55 million-year-old Tertiary sediments. The sedimentary succession is not continuous: deposits from the time interval between 100 and 65 million years ago (Late Cretaceous) are not represented in

2 The geology of Longyearbyen 2.1 Introduction

Svalbard. Either no sediments were deposited at all or the deposited layers were eroded before the Tertiary sedimentation began – a time gap of 35 million years (marked by the double dotted line in the picture of Hiorthfjellet in middle of the book). However, the whole mountainside of Hiorthfjellet from the base to the top exhibits a time span of 85 million years! At the beginning of the Tertiary era, ancient swamps led to the formation of the coal seams in Nordenskiöld Land which became the economic basis for the foundation of Longyear City more than 100 years ago. In Longyeardalen and Adventdalen, it is easy to recognize the bottom of the Tertiary sediments, because all the mine entrances lie like pearls on a necklace at the level of the coal seam.

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The oldest deposits in the Longyearbyen area are Early Cretaceous siltstones at the base of Hiorthfjellet. During this

era, Spitsbergen was characterized by constant shifts between marine and terrestrial conditions due to changes in sea level. Thus, Spitsbergen was land which was repeatedly inundated by a shallow shelf sea. Most of the Cretaceous marine deposits are dark-gray to black mudstones and siltstones which contain very characteristic structures called geodes or concretions. They look like cannonballs and are often perfectly spherical in shape, with diameters up to 30 centimeters. When marine animals die, their bodies – or parts of them – sink to the sea bottom, where they are deposited in and covered by mud. Due to the decomposition of this organic material, chemical processes result in a harder

2.2 The Early Cretaceous time period (145-100 million years ago)

consolidation within spherical aureoles than in the surrounding mudstones. Often, remnants of bones or bivalve shells or ammonites can be found within the «cannonballs». During times of low sea level, the shallow sea retreated and Spitsbergen became land with large flat, river-crossed plains and deltas along the coast. Characteristic sediments are green and gray successions of sandstone and mudstone with abundant plant remains and dinosaur footprints. Spitsbergen’s flat landscape must have been covered by extensive forests: evidence that supports this is the existence of coal seams at the base of Adventtoppen, the mountain ridge opposite Longyearbyen airport. Such coal layers can only be generated by decomposing organic material from growing plants under terrestrial conditions.

Geodes or «cannonballs» at Øienbukta, Bohemanflya.

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2.3 The «missing» Late Cretaceous time period (100-65 million years ago)

In Svalbard, no sediments of Late Cretaceous age are preserved: 100 million-year-old Early Cretaceous sandstones and siltstones are

directly overlain by 65 million-year-old deposits from the Early Tertiary age. Geologists call such a break a «hiatus». In Svalbard, the narrow joint or boundary between the two rock units represents a time gap of 35 million years! What happened in this period? Probably sedimentation continued into the lower part of the Early Cretaceous while Svalbard was slowly uplifted. This uplift raised Svalbard over the water surface of the surrounding oceans – Svalbard became land, and erosion started removing the previously deposited sediments

Footprints of an Iguanodon, a dinosaur up to 8 meters long and 5 meters tall and weighing up to 4.5 tons. These tracks were found close to Barentsburg. The sediments that make up the lower slopes of Hiorthfjellet represent the age when Iguanodon was walking through the Early Cretaceous forests of Spitsbergen.

until the uplift stopped 65 million years ago. Most information about Svalbard’s environment, climate, plants and animals during the hiatus is lost together with the eroded sediments. Worldwide, the Cretaceous – Tertiary boundary represents a major event in the evolution of life on Earth. During one of the most important mass extinctions in Earth’s history 65 million years ago, a huge number of plants and animals – entire genera – suddenly disappeared from Earth’s surface. This was the time when the dinosaurs died out. As one of the consequences, the evolution of mammals exploded after the dinosaurs had died out.

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Modified from C.J.Lüthje (2008).

2.4 The Early Tertiary time period (65-23 million years ago)

When you look from the center of Longyearbyen to the slopes on either side of Longyeardalen, you can see

the cableways of the old coal transportation system and the buildings and entrances of several abandoned coal mines, all at the same altitude at the base of the Tertiary sediments. Here lie several coal seams which are the most important productive coal deposits of Svalbard in Longyearbyen, Barentsburg and Sveagruva.The landscape of Spitsbergen in the Early

Tertiary was distinctly different from what it is today: the characteristic topography with the plateau mountains and vast fjords in central Spitsbergen and the high mountain ranges along the west coast of Spitsbergen did not exist! Sixty-five million years ago, the landscape of central Spitsbergen was dominated by a large bay that opened towards a shallow ocean in the south and was bounded by flat land areas west, north and east.In the area around Longyearbyen, geologists have found evidence of sandy beaches,

tidally influenced lagoons and tidal flats similar to those of the wave energy-dominated shores of the Wadden Sea along the Danish and North German coast. Muddy deposits with high organic content, coal and plant remains are evidence of coastal plain swamps which probably extended from the coast approximately 10 km inland. This coastal plain was protected from waves and storms by barrier bars and islands.

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Satellite image of the North German Wadden Sea (Photo: NASA).

The tidally influenced lagoons, swamps and extensive mires with rich and dense vegetation must have been attractive for grazing mammals. Until recently, no fossil of a land animal had been found in the Early Tertiary deposits to prove the assumption that grazing animals lived in the coastal areas around Longyearbyen. So it was a stroke of luck when the miners Håvard Dyrkolbotn and Kent Solberg found fossilized mammal footprints in the roof of Gruve 7 in Longyearbyen in December 2006. Studying this find, the scientists C.J. Lüthje, J. Milan and J. Hurum could reconstruct the tracks of at least three individuals. The footprints belong to large mammals called pantodonts, which resembled the present hippopotamus: they were up to 2 meters long and weighed 500 kilograms. The new scientific name for the pantodonts in Gruve 7 is Thulitheripus svalbardii: Thulitheri means «great beast from the north», pus means «foot», and svalbardii signifies the location where the footprints were found.

Drawing of the Pantodont footprints in Gruve 7 (C.J. Lüthje (2008)).

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Fossil leaf from Longyearbreen moraine.

and consist mostly of black to dark-gray shale, mudstones and fine-grained gray and green sandstones. As in the Early Cretaceous times, sea level changes led to alternating marine and terrestrial conditions in the Longyearbyen area, with flat coastal plains at low sea levels and shallow inland sea at high sea levels.

It is important to know that Thulitheripus svalbardii is the first pantodont found in Europe, and that pantodonts had been only known from the Early Tertiary in North America before the tracks were discovered in Longyearbyen. So, this finding is additional evidence that North America and Svalbard were still attached together in the Early Tertiary – it was still possible to walk from Longyearbyen to North Greenland. Most probably, the small group of pantodonts came over from Greenland to Svalbard to graze in the rich vegetation of the swamps near the coast of the ancient bay near Longyearbyen. At Hiorthfjellet, the level of the old coal mine marks the point of time, when Thulitheripus svalbardii was walking across the Tertiary swamps of Spitsbergen. In Early Tertiary times, Svalbard had already reached the high polar latitudes where it is situated today. The existence of the coal and very well preserved imprints of leaves in the Tertiary sandstones – not only in Spitsbergen but almost everywhere around the Arctic Ocean – show that the climate on Earth was much warmer than it is today. There were no glaciers and there was probably no sea ice around the North Pole. At the same time, conditions in southern Germany were sub-tropical and palm trees were growing in Paris and London! Sixty-five million years ago, the climate in Spitsbergen was warm-temperate with high humidity equally distributed over the year. The mean annual temperature has been estimated at +12°C in the Early Tertiary – this is significantly warmer than the current mean annual temperature of +8.5°C in Germany! The sediments that were deposited in the time span between 55 and 30 million years ago in central Spitsbergen are monotonous

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In the Early Tertiary, Svalbard was still attached to Northeast Greenland. Due to simultaneous opening of Baffin Bay and

the North Atlantic, Greenland was pushed northeastwards against Svalbard like a bulldozer. This collision produced a 300-kilometer long, folded and thrust-faulted mountain range along the west coast of Spitsbergen, the so-called West Spitsbergen Fold-and-Thrust Belt. It resembles the deformable zones of cars after car

2.5 The collision between Svalbard and Greenland

crashes – but is much, much larger! On both sides of the entrance to Isfjorden, sediments more than three kilometers thick have been turned into a vertical position; the folded rock units are easily recognizable in the mountains. In the Longyearbyen area, the fold structures at the end of the steep cliff along the road to the airport are related to this deformation of the edges of Svalbard and Northeast Greenland.

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Folds along the road to Longyearbyen airport: Lower Cretaceous, 100 million­year­old siltstones which have been deformed, folded and thrust­faulted during the formation of the Tertiary Fold­and­Thrust Belt some 50 million years ago.

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After the deformation that formed the West Spitsbergen Fold-and-Thrust Belt, Svalbard started to break loose from Northeast Greenland.

Thirty-five million years ago, the land bridge between Greenland and Svalbard sank beneath the waves; North America and Europe were finally separated, and Svalbard drifted to its current position.

2.6 The Late Tertiary time period (23-2.6 million years ago)

2.7 Coal

No deposits younger than 30 million years are preserved in the area of Longyearbyen. Like the «missing Late

Cretaceous» they have either been eroded after deposition or were never deposited at all. In this period, the global climate started to cool

down and changed to almost cool-temperate with mean annual temperatures around +8°C in Svalbard. By the end of the Tertiary the climate became increasingly colder until the Quaternary Ice Age started in the Arctic, leading to the situation we know today.

Coal geologySixty million years ago, even though Svalbard was situated north of 70° latitude, vegetation dominated a landscape that looked very unlike the one we see today. Due to the high latitude there was a long polar night just as there is today, but nonetheless the climate was relatively warm and offered suitable conditions for blooming landscapes. There is no comparable place on earth today!

As parts of the land slowly subsided, ground water level rose and coastal swamps could grow thicker and thicker. Where grasses, ferns and horsetail had created stable ground along lakes and lagoons, hazelnut bushes and birch trees moved in and were then followed by trees we might recognize as elm, beech, plane and giant redwood – or at least their ancestors. The land continued subsiding and was flooded while rivers

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transported mud and sand from inland out into the sea. Eventually the former wetlands and mires were covered with several kilometers of sediments. How do we know about those forests and wetlands then? Well, they are still there! The land was pressed up again, luckily rising to even a bit higher than it was 60 million years ago. If we walk inside the coal mines, we can find fossils and imprints of ancient plants in the roof and the surrounding rocks. And the coal itself is nothing else other than peat that has been slowly roasted for some million years at around 80°C. What happened exactly? When the peat was slowly covered by sediments, the water it contained was pressed out and thus it dried, turning slowly into brown coal (lignite). Typically temperature rises by about 30°C per 1000 meters of depth, and at the same time the pressure increases. More and more water is pressed out of the coal and at some point the brown coal changes its chemical structure and becomes black and lustrous. This point is called the geochemical gelification and more or less marks the change from brown coal to bituminous coal – the stuff which is mined in Longyearbyen. The whole process is called coalification and explains how 6-10 meters of peat can be converted into 1 meter of energy-rich coal. If this process were to continue, further increases in temperature, pressure and time would turn the coal into anthracite, graphite and, at very high pressure, diamond. The mine in the old Advent City on the northern side of Adventfjorden produced cretaceous coal. All the other mines in Longyearbyen worked early Tertiary bituminous coal. We can imagine the coal layers in the surrounding mountains as the jam in a layer cake. In an up to 50-meter thick succession of

sandstone, mudrock and conglomerate, we can find five main layers of coal, so-called seams. The seams have been given names: the main seam here is called Longyear seam. At the bottom we find the Svea seam (which is more than 5 meters thick at the active mine Svea Nord, 45 km southeast of Longyearbyen), overlain by the thin Todalen seam. Above are the Svarteper and Askeladden seams. Between the seams, layers of mudrock, sandstone and conglomerate tell geologists a story about tidal flats, beaches and rivers 60 million years ago. To find out if a seam is worth mining in a specific area, a many analyses and evaluations must be done. Factors such as coal seam thickness, content of inorganic material (so called ash), sulfur content, energetic value and the location of the coal field decide whether mining can be done economically or not.

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Mining operation inside Gruve7 (Photo: Tommy Dahl Markussen; SNSK).

Coal miningAll the mines in the vicinity of Longyearbyen are underground coal mines. In 1906 the American «Arctic Coal Company» started mining in the valley that is now named after the founder John Munro Longyear. In 1916 the Norwegian «Store Norske Spitsbergen Kulkompani» (SNSK) bought Longyear City and has been mining in the Longyearbyen area ever since (apart from two years during the Second World War). SNSK is Norway’s only coal mine, the northernmost active mine in the world and produces without subsidies. SNSK’s mines are numbered, Gruve 7 (Mine 7) is active today. Though the old mines have been abandoned, most of the installations are preserved and visible on the mountainsides (see 2.1). Most of the coal was transported to the harbors by cableway. SNSK’s main office is situated in Longyearbyen. The main activity, however, is in Sveagruva: the mine «Svea Nord» started production in 2002 and is the most productive mine ever in Svalbard. At its peak, the annual production was more than 4 million tons! For comparison, all the other mines worked by SNSK have produced about 27 million tons since 1916. Today (2012), SNSK is opening up a new mine, called Lunckefjellet.

Compared to Svea Nord, Gruve 7 is a small mine with just over 20 employees and an annual production of 90 000 tons. It works the Longyear seam with a thickness between 1 and 2 meters, typically 1.6 meters. The coal is extracted using the technique called «room and pillar»mining; this production method allows 70-80% of the coal to be exploited. The rest of the coal is left in place as pillars that maintain stability in the mine. The bulk of the coal from Gruve 7 is shipped to Germany where it is used in the metallurgic industry as an important factor in the production of car engines, among other things. The coal is of very good quality and requires no washing. The rest of the coal (about 25,000 tons/year) is used in the local power plant to generate electricity and community heating for Longyearbyen. The coal is transported by truck through Longyearbyen to the harbor and the power plant. Sometimes the trucks lose lumps of coal. If you are lucky enough to find a specimen beside the road, pick it up. Look at the luster and the layered structure; maybe you will even find a leaf imprint. Can you imagine the plants this black lump is made of? Close your eyes and imagine the warm wind, the smell of the swamps and the rustling of the leaves of the giant trees that grew here in the Arctic 60 million years ago!

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3 Quaternary – the present landscape around Longyearbyen

During the ice age, Svalbard was repeatedly covered by huge ice sheets with formidable destructive power. Nevertheless, the most important large-scale landscape features around Longyearbyen have survived from times far more ancient than the last ice age. The best examples are the wide mountain plateaus that are characteristic of Longyearbyen’s surroundings. If you were to connect the plateaus across today’s valleys, you would essentially get the landscape as it would have been many million years ago: a wide, rolling peneplain near sea level, with low hills and muddy rivers. The wide, shallow valleys of these rivers probably created today’s system of fjords and valleys such

3.1 Remnants of the pre-ice age landscape: peneplains, isolated mountains and valleys

as Isfjorden and Adventdalen. A few isolated mountains had resisted erosion while the surrounding bedrock was worn down through many million years and towered 500 meters or more above the plain, just as they do today (e.g. Nordenskiöldfjellet). Over the next millions of years, uplift raised the plains to higher elevations, creating the mountain plateaus. Uplift also led to increased erosion, thus turning the wide, shallow river valleys into deep valleys with steep slopes. With the onset of the ice age, these valleys were repeatedly filled with glaciers that created typical glacial U-shaped valleys with steep slopes and wide bottoms (Longyeardalen, Bjørndalen).

3.2 The ice age: continental ice sheets come and go

Nordenskiöldfjellet towering over Plateaufjellet. Bjørndalen, a glacial valley with U­shaped cross section, incised into a pre­glacial, uplifted plain.

During the past two million years, northern Europe has time and again been covered by vast ice sheets stretching from Svalbard to the southern Baltic Sea area. Twelve thousand years ago, Isfjorden was completely filled by a huge glacier extending well beyond its present-day mouth. This glacier later retreated even beyond the margins of today’s glaciers. Plant remains that were found under Longyearbreen turned out to be at least 1,100 years old. This shows that for a long time, Longyearbreen was much smaller than it is today and had to grow by two

thirds to assume its modern appearance! During the Little Ice Age around 1850, it advanced markedly to reach its maximum size. Since then, Longyearbreen – like many other glaciers both in Svalbard and worldwide – has been shrinking due to the global warming that followed the Little Ice Age, a trend that has recently been accentuated owing to emission of artificial greenhouse gases. Thanks to the moraine cover at its lower terminus, Longyearbreen has essentially kept its length, but it has become up to 30 meters thinner over much of its area.

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3 Quaternary – the present landscape around Longyearbyen

Larsbreen.

Historical picture of Vannledningsdalen and its avalanche sediments/alluvial fan (Photo: Vestby; SNSK).

Old beach ridges at Revneset highlighted by snow patches.

The volume changes of the large Quarternary ice sheet left quite obvious traces in the landscape. The more than 1000 m thick ice mass pressed the Earth’s crust down by about 200 m. Once most of this ice had disappeared, the crust reacted elastically and started to pop up again, returning to its original position. This uplift resulted in retreating shorelines. Traces of this process remain in the form of beach ridges and occasionally driftwood, whalebones and seashells well inland. Near Longyearbyen, the highest traces of former

coastlines are 60-70 m above sea level and date back 10,000-11,000 years. You can find quite obvious fossil beach ridges at Hotellneset, Revneset and the entrance to Bolterdalen, where even whalebones and seashells have been found in the marine sediment, kilometers away from the modern day coastline.

3.3 Water erosionSvalbard’s rivers are frozen for most of the year. In late spring, the snow cover is able to store meltwater for some time, but when its storage capacity is exceeded, huge meltwater floods will rush down the river beds. These floods can last for a couple of hours or even days. The meltwater, which is mixed with snow, ice, mud

and stones, can cause dangerous slush torrents («avalanches»). This happens especially when there is a lot of snow in the catchment area, combined with a warm period to saturate the snow with meltwater and finally another warm spell and rain to trigger the event.

3.4 Vannledningsdalen: hazardous slush torrentsOn 11 June 1953, parts of Haugen were destroyed when a slush torrent rushed down Vannledningsdalen. Several houses were ruined, three people lost their lives and 30 were injured On 14 June 1989 and 30 January 2012, other slush torrents caused damage in the same area, both times without harming any people. To prevent further damage, endangered houses have been protected with avalanche fences and the river has been channeled with dams. In steep, narrow river beds such as Vann-ledningsdalen, meltwater can transport huge volumes of sediment that are deposited again as soon as the river has left the steep and narrow section, and entered flat terrain. Over time, the deposits will gradually form an alluvial fan.

Fossile seashell in Bolterdalen.

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Longyearelva in its artificial bed.

Multiple channels of Janssonelva north of Janssonhaugen in Adventdalen.

The estuary of Adventelva. In the upper left, the large alluvial fan from Mälardalen can be seen.

3.5 One tamed and one wild arctic river: Longyearelva and Adventelva

During the snow-melt period in early summer, the brown, muddy water in Longyearelva can rise to impressive levels. You may hear large stones rumble along on the river bed. When a valley bottom is flat and wide as in Longyeardalen, the river will develop many channels: Large volumes of sediment from frost-shattered rocks and glacial erosion in the catchment area overload the river, which has only the short summer to transport all sediments into the sea. At the end of the summer, as water levels are fall, stones, gravel and sand will remain where they are, blocking the river channel with a new gravel bank, forcing the river to move sideways or split into two smaller channels the following year. Arctic rivers that carry a huge sediment load and have plenty of space on the wide valley bottoms usually split up into a multitude of channels (braided river system). Longyearelva has been forced artificially into one channel to gain space for the settlement. In contrast, Adventelva in the lower, wide part of Adventdalen, has many intertwined channels. The river mouth of Adventelva is an estuary, influenced by tides and waves. There is no sharp boundary between land and sea or between river and fjord. Instead, there is a large, very shallow area that falls partly dry at low tide. The muddy freshwater of Adventelva provides a strong contrast to the clear saltwater of the fjord. The freshwater has lower density than the seawater and remains as a thin layer at the surface before it eventually mixes with the seawater.

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Bassen with ice cap and the famous snow field shaped like a champagne glass.

Moraine of Longyearbreen showing some collapse structures.

3.6 Islands on the rocks: GlaciersDue to the relatively dry and mild climate, only 18% of the land area around Longyearbyen is covered by glaciers. That is little compared to the rest of Svalbard, where glaciers cover about 60% of the land area. Most glaciers near Longyearbyen are small isolated valley glaciers, and there are only few ice caps. One is on top of the mountain Bassen. Another one is Foxfonna, southeast of Gruve 7 in Adventdalen. Both ice caps are thin and move only slowly. Glaciers can move in different ways. The ice mass can slide as a whole block. This happens in «warm» (temperate) glaciers where the temperature is at the pressure melting point near 0°C. These glaciers are kept «warm» by meltwater that penetrates into the glacier ice and then re-freezes at the bottom, emitting melting heat and thus warming up the surrounding ice. The resulting thin water layer between the ice and the underlying bedrock serves as a lubricant. The glacier can slide. This type of movement, called basal gliding, is quite efficient and can result in velocities of several hundred meters per year. Huge ice masses sliding across a rock surface can cause strong erosion. The glaciers near Longyearbyen are mainly cold glaciers. Cold glaciers have a temperature

below the pressure melting point and are frozen solid to the underlying ground. They can only move by means of internal deformation under the influence of gravity. This movement is much slower than basal gliding – amounting to only a few meters per year – and does not cause much erosion: cold glaciers can even preserve pre-glacial landscapes. Below the ice of Longyearbreen, there is still a V-shaped cross section, created by a river in pre-glacial times and similar to Vannledningsdalen, a typical river-created valley. Longyearbreen has a maximum thickness of 115 meters and is moving at a speed of 2 to 4 meters per year.

3.7 Landscapes created by glaciers: moraines and valleys

From the surrounding slopes, frost-shattered rocks fall on a glacier surface and will move together with the ice until they finally reach the lower end of the glacier, where they form a moraine. There is usually a core of glacier ice under the rocks, which can make up more than 90% of the total volume of the moraine. Mudslides, mudholes and slippery, instable terrain are common on ice-cored moraines.

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Rock towers and debris flow track at Vestpynten.

The steep slopes surrounding Longyearbyen are areas where important landscape-shaping processes take place. The huge volume of broken rocks that covers the lower slopes is provided by frost shatter, which can attack porous sedimentary rocks quite efficiently. Meltwater penetrates into pores and cracks; in autumn it will freeze and

3.8 Steep and active: slopes

3.9 Rock towers and avalanche funnels

3.10 Debris flows

Frost will attack any rock surface, but is more efficient in some places than in others. Avalanches often create funnels that will be retraced and enlarged by future avalanches. These funnels have individual catchment areas of a certain size depending on the rock type and how easily it is eroded. The funnels are

During heavy rain events in summer and during the snow melting season, impressive mixtures of water, mud, and rocks can rush down the steep funnels with velocities of up to 60 km/h. The tracks of such debris flows are only a few meters wide but can be several hundred meters long.

expand, thereby breaking the rock. The ice serves as mortar during the winter and it is not until spring, when melting starts again, that the rock will actually fall apart. At this time, many rocks fall and avalanches occur and large volumes of rock accumulate on the lower slopes, forming either continuous scree slopes or distinct talus cones, if they fall down along discrete channels.

separated by protruding rock towers. If the rock type is similar over a large horizontal area, the catchment area sizes will also be similar. In these cases a very regular pattern of rock towers separated by incised funnels can be found, reminiscent of gothic cathedrals or fortresses.

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The rock glacier on Hiorthfjellet.

3.11 Rock glaciers

3.12 Permafrost and climate

A rock glacier is a solid body of rocks and ice that develops when meltwater percolates between the rocks and freezes in the permafrost area. It remains frozen for a long time and fills the hollows between the rocks completely. The whole mixture can deform under the influence of gravity and move slowly downhill at a speed of a few centimeters per year. Avalanches contribute significantly to supplying rock glaciers with debris and ice. There are several nice examples of rock glaciers around Longyearbyen.

Active rock glaciers depend on permafrost. In Svalbard, almost all of the unglaciated land surface is permanently frozen except the uppermost «active layer» that thaws during each summer. The thickness of the active layer depends on the substrate, exposure, moisture, vegetation cover and on the thickness and duration of the snow cover. The thickness of the active layer has increased in recent years due to a warming climate, and the temperature of the underlying permafrost has increased. A deep and long-lasting snow cover protects the ground effectively from the severe cold of the winter, but wherever the snow is blown away by wind, the surface is exposed. As a result, the greatest permafrost thicknesses have been found on exposed mountain plateaus and ridges such as Sarkofagen, where the ground is permanently frozen down to a depth of 450 meters. In valleys the permafrost layer may be only 100 meters «thin».

The ski jump competition «Svalbardkollen» in 1932 was held on a rock glacier in Longyeardalen (Photo: SNSK).

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Pingo on the northern side of Adventdalen at the opening of Mälardalen.

Polygons in Adventdalen beside the road to Todalen. See cabin for scale.

3.13 Pingos

3.14 Polygons of ice wedges

Pingos are little hills that can be between 10 and over 30 meters high and have a diameter of more than 100 meters at their base. Pingos have a thin outer layer of soft sediment but most of their volume consists of solid ice. Most pingos can be found on the bottom of large valleys.The formation of a pingo can start when groundwater flows from the catchment area of a temperate glacier into the layer under the permafrost. There it is under pressure but cannot easily escape through the permafrost. The groundwater will have to find weak zones within the permafrost to reach the surface. Such zones are often found in valleys with big rivers. Their water helps to keep the permafrost weak.

During summer, groundwater can reach the surface in these areas, but as soon as the surface is frozen, the water is captured below the surface. There it will re-freeze to form an ice body that can grow and survive for many years. During the summer, there is usually a small artesian spring somewhere on the pingo, which can create a large ice-covered area on and around the pingo in autumn. The pingo nearest to Longyearbyen is at Moskuslaguna on the northern side of Adventfjorden, but there are more pingos in Adventdalen.

Ice wedges are wedge-shaped bodies of solid ice and can be found mainly on even surfaces. The visible part usually consists of quite inconspicuous, elongated depressions only a few centimeters deep and wide. These depressions run many meters through the tundra and several ice wedges form a network of polygons, mostly pentagons and hexagons, with 10-25 meters across. Occasionally, small rivers can enlarge the depressions into trenches of more than a meter in depth and width.

The development of an ice wedge starts with frost cracks that form in the soil during winter. The cavity will be filled with ice crystals or re-freezing meltwater that may survive the following summer within the permafrost layer. This process is repeated over a long time span whenever the winter temperature drops to about -15°C or lower. Over centuries, ice wedges can become up to a meter thick and extend 10 meters into the ground, depending on how far down the ground temperature varies over the year.

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Ruler

GPS

Geological compass

Proper clothes!

Hammer

Helmet

Safety goggles

Hand lens

Field book & pencil

Map

Camera

Family excursion in LongyeardalenThis is a geological excursion for families with children or just anyone who wants to get some exercise but doesn’t want to emulate a mountain goat. It can be done as a round trip in the Longyear valley and takes 1-3 hours. It follows roads all the way but can also be extended with short excursions off-road.

Trollstein - excursion for mountain goats This excursion takes 4-7 hours and requires good shoes and mountaineering clothes. Be sure to take along a proper map, compass or GPS, walking sticks, rifle and signal pistol. Orientation can be very difficult on the plateau-mountains when the visibility is poor. The glaciers are normally fine to walk on without crampons but it won’t hurt to bring crampons. Be careful on the glaciers! The meltwater channels on a glacier’s surface can be hard to cross – and they can be covered by snow!

Excursion by car to AdventdalenIf you have a car available or are a sporty cyclist you can take this excursion into Bjørn- and Adventdalen. This jaunt also requires good shoes, a rifle and a signal pistol with you if you want to see the stops that lie some distance away from the road.

Geological excursionsWe suggest three excursions, depending on your schedule and circumstances:

What a real geologist brings along:

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Family excursion in Longyeardalen(1) Soil creep: Beside the road you see tilted wooden stumps. These are the piles the houses of old Longyear City were built on. The houses burned down during the Second World War. The stakes were vertical at the beginning of the 20th century. The tilt is a sign of movement of the active layer, which slowly creeps downslope. At the same time the piles are pushed up due to frost heave. See chapter 3.12.(2) Rock towers: The yellowish cliff two-thirds of the way up the slope are part of a sandstone layer. This more or less horizontal layer resists erosion better than the overlying siltstones and therefore forms cliffs. See chapter 3.9.

(3) Mud flows: Most of the mud flows in this area are from the same extreme rain event which occurred in August 1972. During this event 31 mm of rain fell in 48 hours. As a result, the active layer became oversaturated with water and was destablized. The wet mud ran downslope and formed channels. Typical for such mud flows are the levees on either side of the channels and the fans at the lower end. Some of the channels even crossed the road. See chapter 3.10. Rolling stones: Blocks break loose from the cliffs of the sandstone layers and tumble down the slope, especially in the early winter when temperatures change a lot and in early summer when temperatures rise. Sometimes the boulders roll all the way to the river bed. See chapter 3.8. (4) Rock glacier: The terrace at the foot of the slope behind Huset was used as a ski-jump in the old days. Those terraces are rock glaciers. See chapter 3.11. (5) Level of the coal seam: The installations of Gruve 1A (the American mine) are clearly visible high above the church. The opening of Gruve 1B is just above Sverdrupbyen; Gruve 4 is at the foot of Sarkofagen. On the other side of Longyeardalen you see Gruve 2B and the leavings from Gruve 2B at Sukkertoppen. Look across to Hiorthfjellet and you may discern the installations of the mine far up on the mountainside. All these mines exploited the same geological coal level, namely the Longyear coal seam. Imagine the coal as the jam in a layer cake. The cake is tilted slightly towards you and the big erosion monster (i.e. ancient glaciers) has «eaten» (eroded) the part of the cake where the valleys Longyeardalen and Adventdalen are today. Before erosion, these too were filled with coal and rock. See chapter 2.1, 2.4 and 2.7. (6) Alternative: Longyearbreen and fossilized forests: See (20).Walk back to Huset and cross the valley. (7) Alternative: Larsbreen: Walk up to Nybyen and continue along the river to Larsbreen. Bring a rifle! At the end of the valley you see the river coming out of the meltwater channel of Larsbreen’s ice-cored moraine. In winter it is possible to enter this «moraine cave». See chapter 3.6. and 3.7. (8) Alternative: Gruve 2B, Santa Claus’ home: climb up the steep slope to Gruve 2B. This mine entrance was established in 1937. In 1943 the mine caught fire during the German attacks and burned until 1962. In 1959 the leavings outside the mine entrance started burning spontaneously: self-combustion. The red, oxidized rock material outside Gruve 2B bears witness to those fires. Gruve 2 was finally closed in winter 1967/68. SNSK maintains the installations and it is possible to enter some of the buildings. Every year in Advent season, Santa Claus moves in here. The children of Longyearbyen deliver their Christmas wish-lists to the mailbox he sets up at the road in Nybyen. See chapter 2.7. (9) Avalanches: behind Spitsbergen Hotel you see the artificial ridge that was built after the catastrophic avalanche in 1953, when three people lost their lives. The avalanche was a slush avalanche that came down Vannledningsdalen with destructive power. (9b) The little footbridge «Perleporten» (The Pearly Gate) was partly destroyed during a slush avalanche in late January 2012. See chapter 3.4. (10) Longyearelva, a tamed arctic river: Before humans came here the river bed covered the entire width of the valley. Today, diligent work with earth-moving equipment keeps the river in its artificial bed – and away from houses and roads. In winter the river dries out completely. See chapter 3.5. (11) A rising island, raised beaches: It is not easy to see anymore, but several of the rows of houses are built on raised beach terraces. If you walk to the end of Vei 236, you can clearly trace the line of the old beach. See chapter 3.2. You can end your excursion with a visit to Svalbard Museum and learn more about Svalbard’s fascinating geology.

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Excursion to Trollstein – for mountain goats(12) Tidal flat: The innermost shoreline of Adventfjord is a big tidal flat. At low tide you can walk out on the tidal flat and look for traces of benthic marine animals such as worms and shellfish. You might also be able to see nice sedimentary structures such as ripplemarks, created by water currents. At high tide the whole area is flooded. See chapter 3.5.Pass the dog pen and follow the road upwards into the valley.

(13) Svalbard in Cretaceous times: Pass the dam on the grassy ridge to the left and descend into the valley. The steep rock walls are composed of sedimentary rocks. See (27). You might find embedded structures that resemble those from the last stop at the tidal flat. (14) Svalbard in the Tertiary: As you walk up the valley, look for changes in the rocks – very observant geologists might discover a conglomerate layer that marks the “missing” late Cretaceous time period as described in chapter 2.3. When you reach the level of the mine entrance (which is to the right) and if the valley is not filled with snow, you can see the best example of an outcropping coal seam in the vicinity of Longyearbyen. The well laminated coal is overlain by thick sandstone beds. You are in the Tertiary Firkanten Formation. See chapter 2.4. and 2.7. (15) Frost weathering: Walking is difficult on the plateau mountain. Due to freezing and thawing processes many of the sandstone rocks are standing vertically. You might also see frost separation processes as patterned ground. See chapter 3.12. (16) Svalbard in the Tertiary, sea level changes: Sandstones resist erosion quite well and it is thus the thick sandstone layers that form the plateau mountains in this area. Where the Trollstein ridge starts you walk upwards onto dark mudrock. The landscape formations get smoother because mudrock is easily weathered. You walk upwards with geological time: after deposition of the sands close to the beach some 58 million years ago, sea level rose and the shoreline moved inland. The former beach was suddenly 100-200 meters below sea level. The sand from the coast did not reach that deep into the marine basin and was deposited elsewhere. Where you are standing, only the muddy particles were deposited. Remnants of plants and animals also sank to the bottom and contributed to the high organic content that is responsible for the dark colors of the rocks. (17) Svalbard in the Tertiary, the filling of a marine basin: As you walk up the beautiful ridge, note how more and more sandstone layers intercalate the mudrock. The top of Trollstein consists again of pure sandstones which form manifold sedimentary structures such as dunes and ripples. You might see heavily folded structures that developed when an earthquake triggered a submarine sand slump around 50 million years ago. The change from the lower mudrocks to the overlying sandstones tells us the story of a basin that slowly filled up with sediments: the ancient shoreline was much closer here on top of the mountain than in the layers further down where we only find mudrock. Nordenskiöldfjellet is even higher. There we can find coal and plant fossils at the summit, a sure sign of terrestrial deposition. The basin was totally filled up with sediments at the place and time when the coal was deposited as peat. There were originally coal-bearing layers also above Trollsteinen, but these have been eroded by glaciers, wind and weather. (18) A changing glacier, Larsbreen: Many signs that show us that Larsbreen is not as thick as it has been. These moraine cones were once covered by ice. Careful study of the moraines also shows that Larsbreen once hung over towards Longyearbreen. See chapter 3.6.Alternative at (18): walk down the moraine of Larsbreen instead of walking to Longyearbreen. (19) Meltwater channels: In winter it is possible to enter the glacier by following the channels. A fascinating experience! (20) Longyearbreen and fossilized forests: When you come to the rocky moraine of Longyearbreen, lift up some rocks. Do you see that there is mainly ice below them? See chapter 3.2 and 3.7. Stroll around and look for hints of a warmer climate in Svalbard once upon a time – you can find amazing imprints of fossilized leaves and trees, remnants of the huge forests that covered Svalbard some 45 million years ago! The leaves are from the Tertiary deposits at Nordenskiöldfjellet. See chapter 2.4.(21) to (25): see (5) to (1)

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Excursion by car to Adventdalen(27) Svalbard in Cretaceous times: Walk along the cliffs at the shore. Pay attention to the different rock types you encounter: mudrock, silt- and sandstone from the Cretaceous Carolinefjellet Formation. These sediments were deposited on the sea floor around 100 million years ago. You can find beautiful sedimentary structures and trace fossils. You can also find marine fossils such as shells and (rarely) ammonites. Look for cannon-balls! With a lot of luck you can find fossilized wood here. See chapter 2.2.

(28) Rockfall and mudflows: see excursion stop (3). (29) Raised beaches: Between the road and the end of the runway you can see differences in the vegetation, arranged like horizontal stripes. Those differences represent different ancient shore lines from the time since the last Ice Age. See chapter 3.2. (30) Island collision, folding. In the cliffs beside the road you can see how the sedimentary rocks are folded. See chapter 2.5. The layers are part of the Cretaceous Carolinefjellet Formation, see excursion stop (27). (31) Longyearelva, a tamed arctic river: See (10). (32) Adventelva, a wild arctic river: Adventelva is still wild and changes his braided river beds every year. See chapter 3.5. (33) Longyearbyen CO2-lab: Store Norske Spitsbergen Kulkompani and UNIS started a project to realize the dream of storing CO2 from the coal-fired power plant in the rocks deep under Adventdalen. Most of the drill holes from this scientific project are here, and a visitors’ center is planned. (34) Coal mines: On the western side of Endalen you see the mine openings of Gruve 2, which goes through the mountain all the way to Longyearbyen. Gruve 2 has been the most productive mine in the Longyearbyen area. On the eastern side of Endalen the mine constructions of Gruve 5 are clearly visible. See also (5). (35) Permafrost and frost creep: UNIS has a measuring station that registers frost creep and temperature. At www.unis.no you will find online temperature data down to 19 meters. See chapter 3.12. (36) Ice wedges and frost polygons: Beside the road can you see large polygons and lines. In the depressions that form these patterns, massive ice wedges are hidden. See chapter 3.14. (37) Whale bones and mummified shells on an ancient shore terrace: Where the road makes a sharp left turn stop the car and continue a bit into the small valley. Here you can find shells in their living position (even the mummified body is preserved!) and whale bones that have been dated to an age of 10,000 years. You will also find typical foreshore sediments and marinoglacial sediments. You are standing exactly where the shore was 10,000 years ago when the land was still much lower. See chapter 3.2. (38) Gas below the permafrost: North of the Bolterdalen bridge you can see a metal pipe sticking out of the ground. This is a coal exploration drill hole, drilled in 1967. From below the permafrost at a depth of 105 meters, gas came up the hole and continued for more than one decade until the hole was sealed. Even today there is gas pressure in the well. The gas burns well and consists mainly of methane generated by the coal. The permafrost forms the top seal for the gas. (39) Mine 7: The only active coal mine in Longyearbyen. See chapter 2.7. (40) Enjoy the fantastic view over Adventdalen. Imagine the valley filled with water, as a big fjord, just as it was 10,000 years ago. Try also to imagine the ancient landscape before the deep valleys were cut in by erosion (see chapter 3.1). From here you can see: (40a) The ice cap at Bassen. See chapter 3.6. (40b) The pingos in Adventdalen. See chapter 3.13. (40c) The braided river system and the estuary of Adventelva. See chapter 3.5.

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In this booklet, we want to take you on an exciting journey through the ancient past in the surroundings of Longyearbyen. To put things in context, we start with a short description of the geological history of Svalbard. Then we zoom in on the geology and the landscape you can see in and around Longyearbyen today. As an example, we will use Hiorthfjellet, the prominent mountain that greets the people of Longyearbyen from the other side of Adventfjorden. Its mountain slope exhibits 85 million years of Svalbard’s history.

AcknowledgementsWe are very grateful to the Svalbard Environmental Protection Fund and Store Norske Spitsbergen Kulkompani for funding this booklet. Thanks also to Elke Morgner for comments, Bjørn Frantzen and Karin Stensson for encouraging us along the way and Tiril Varpe, the youngest geologist model in Longyearbyen.

10,000-year-old whale bones (to the left) in the river bed of Bolterdalen. Hiorthfjellet in the background.