The geological layers are easily seen. Photo: Herta Grøndahl
Tempelfjellet, one of the most beautiful mountains in Svalbard. Photo: Herdis Lien
The gypsum mine in Skansbukta. Photo: Herdis Lien
THE GEOLOGICAL STORY
In Svalbard we find rocks from practically all the geological time periods. In few places does the geology show better than in Svalbard where the vegetation is very sparse. This has amazed geologists since the first Norwegian geological expedition of Keilhau in 1827. Today, Svalbard is a very popular place for geologists from around the world.
Svalbard looks almost like a landscape from the end of the ice age. It is bare, the vegetation is sparse and over half of the land is covered in glaciers that are pushing forth moraines. The rivers carry stones, gravel and clay, and these are laid as flats in the valleys and as deltas out in the seas.
THE OLDEST ROCK TYPES
The oldest rock types are from the Precambrian period (>1000-440 million years ago) and make up the bedrock, consisting of metamorphosed sedimentary and igneous rocks such as mica slates and gneiss and intrusive rocks such as granites. We find few fossils from the Precambrian. This is owing to the strong metamorphism of the rock types from this time, and that life was in an early stage of evolution.
MOVEMENT OF THE EARTH’S CRUST
Over 400 million years ago the earth’s crust in the Svalbard area was in motion. Mountain chains were formed (the Caledonian mountain chain) that the granite intruded. Granites make up some of the highest, present-day, mountain peaks on Svalbard. Later erosion has broken down the greatest part of this mountain chain.
Later came the Devonian period (circa 375 million years ago). During this period the central parts of Spitsbergen subsided. Immense layers of sediment, several thousand meters thick, were deposited. This deposition occurred during a dry climate, both on land and in the fresh and brackish waters. The oldest primitive armour-plated fish are found in these rocks together with some primitive plants.
The Carboniferous period was humid. During this period sediments were deposited in shallow seas and on flat low-lying land areas. Sand, clay and plant remains from the swamps gave rise to sandstone, slate and layers of coal. 300 million years ago the sea flooded the land areas, and limestone, dolomite and layers of anhydrite and gypsum were deposited. We find layers that are rich in sea fossils from the end of the Permian period (250 million years ago).
THE TRIASSIC, JURASSIC AND CRETACEOUS PERIODS (250-65 MILLION YEARS AGO)
Millions of years ago Svalbard was located much closer to the equator than it does today. During the Triassic, Jurassic and Cretaceous periods Svalbard moved from 50° to 70° north and the climate was temperate and humid. Rocks from this period are rich in sea fossils. Volcanic activity led to the formation of igneous rocks in the strata.
THE TERTIARY PERIOD (65-2 MILLION YEARS AGO)
There were strong movements in the Earth’s crust during this period, which led to mountain formation. At the same time large swamps formed in the central areas of Spitsbergen. These swamps have given rise to the coal deposits around Longyearbyen, Sveagruva and Barentsburg.
In the last 2 million years volcanic activity and ice ages have influenced the geology. Evidence of volcanic eruptions 70,000 years ago and the present-day hot springs bear witness to this activity. Thousands of meters of rocks have in many places been worn away by the latest ice ages. Slowly, the landscape of Svalbard, as we know it today, has been formed.
WHAT IS COAL?
Many million years ago in Svalbard, dead plants and animals were buried in sand and mud for long periods of time before they decomposed. The weight of the deposits above lead to high pressure and rising temperature. In the coarse of millions of years the remains of the plants and animals were transformed into coal, oil and gas.
Peat bogs were weighed down and carbonized. They slowly became “fossil solar energy” – intercepted through photosynthesis and preserved until today. These processes still continue. But since such processes are very slow, we recognize coal, oil and gas as non-renewable energy resources. The ice sheet has over the years tore at the overlaying deposits with the result that the coal-bearing layers today are close to the surface. Several places they actually are to be found out in the open.
By Torfinn Kjærnet