Geology Topography and Quaternary Glaciations

The islands are formed from Tertiary plateau basalts, about 50-60 million years old, with a total thickness of at least 5200 m. The land surface rises gradually from about 600 m a.s.l. in the southwestern part of the islands to more than 800 m a.s.l. in the northern and northeastern areas, which have a mountainous topography. Lava flows form benches on hillsides. The highest

NORWEGIAN SEA

NORTH ATLANTIC OCEAN

W.SHETLAND • ISLANDS

NORWEGIAN SEA

NORWEGIAN SEA

Eysturoy

Eysturoy

ISLANDS

Suduroy

NORTH ATLANTIC OCEAN

Sando^^} FAROE

ISLANDS

Suduroy

NORTH ATLANTIC OCEAN

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Location and main towns and islands in the Faroe Islands.

mountain, Sl&ttaratindur (882 m a.s.l.), is situated in the northern part of the island Eysturoy. There are many smaller rivers that have been dammed for hydroelectric power, and the coastline is indented by many fjords and steep cliffs. The Tertiary volcanics overlie Cretaceous clays and sandstones that appear to be cap rocks for hydrocarbons trapped in Devonian and Carboniferous source rocks in the Faroe-Shetland Basin. There are some Tertiary brown coal seams on the island of Su5uroy, mined for local use.

Since the Tertiary volcanic evolution, when the present-day Faroes were located close to the present southern central part of East Greenland, coastal erosion has gradually reduced the area of the islands, simultaneous with slow sinking of the basalt plateau due to cooling and isostatic effects. Following cessation of volcanism, the humid and warm Tertiary climate caused strong chemical erosion, by which a low-relief (100-200 m) rolling landscape evolved during the late Tertiary.

300 Miles .

ICELAND

ISLANDS

During the Quaternary, recurrent glaciations and cold-climate weathering have left significant geomorphological imprints such as glacial trough valleys, cirques, free faces, talus sheets, and solifluc-tion lobes. According to a regional mapping of glacial striae, many large valley glaciers grew in the Faroes during the Weichselian, covering the landscape up to at least 700 m a.s.l. in the northern central part of the islands, and extending several kilometers beyond the present coastline onto the surrounding shelf. Assuming a postglacial eustatic sea level rise of about 125—130 m, the regional maximum Weichselian ice thickness, however, could not have exceeded 350—400 m, as there are no raised beaches on the Faroe Islands.

Little is known about the Late Weichselian deglaciation of the Faroe Islands. A series of rather small moraine ridges relating to a final valley and cirque glaciation have recently been described, and a tentative Younger Dryas age was suggested by comparison with similar moraine systems in Scotland. To date, a proper dating of the moraines has not been successful, and it is therefore not known precisely when the Faroe Islands became ice-free in the Late Weichselian. The oldest relevant radiocarbon date is obtained from a lake bottom core at Hoydalar and gives an age of 9660 ±150 BP (Johansen, 1975, 1985), indicating that glacier ice may have been present in some large valleys up to the beginning of the Holocene. There is no indication of any Holocene reglaciation in the Faroe Islands.

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