Jökull - 01.12.1979, Side 76

9 Glaciers in Iceland
HELGI BJÖRNSSON
Science Institute, University of Iceland, Reykjavík
INTRODU CTION
Iceland is a mountainous country located in a
region of high cyclonic activity at the border of cold
polar air masses and w'arm air masses of tropical
origin. The tracks of the atmospheric depressions
crossing the North Atlantic usually lie close to Ice-
land. Further, the climate is affected by the con-
fluence of warm and cold oceanic currents, namely
a branch of the Gulf Stream and the polar East
Greenland Current. The climate is maritime with
low summer temperatures and heavy winter
precipitation. When the East Greenland Current
carries arctic drift ice towards the Icelandic coast,
both air temperatures and precipitation are
seriously affected.
The climatic conditions and the topographical
features result in high glacieration. About 11%
(11.200 km2) of Iceland is covered by ice at present.
Almost all forms of glaciers are represented, from
cirque glaciers to extensive plateau ice caps. All
glaciers in Iceland are of the temperate type. The
glaciers are very dynamically active and responsive
to climatic fluctuations, and they have greatly
affected the landscape of Iceland by means of
erosion and deposition.
GLACIER DISTRIBUTION
Three glacier regions can be distinguished in
Iceland. The northern region comprises the North-
west Peninsula and the Tröllaskagi area between
Skagafjördur and Eyjafjördur (Fig. 1). Both areas
are built of Tertiary basalts. In the NW Peninsula
an extensive plateau lies between 700 m and 900 m
above sea level. The highest part of the northern
plateau is occupied by the ice cap Drangajökull
(about 160 km2). The maximum elevation of the ice
cap is 925 m and the average elevation is only about
630 m above sea level. Two outlets from the ice cap
flow down to the costal region and terminate below
200 m elevation. A number of niches and about 10
small cirque glaciers are situated beneath the
plateau remnants between 600 m and 700 m ele-
vation.
Tröllaskagi is the highest mountain range which
radiates out from the central Icelandic highland.
The landscape is Alpine and many mountains
reach up to 1300—1500 m elevation. About 115
cirque and valley glaciers of the Alpine type are
found in Tröllaskagi. Only a few of the glaciers are
raore than 1 km2 in area. The total area covered by
ice in Tröllaskagi is approximately 40 km2. The
most active valley glacier is Gljúfurárjökull (2.4
km2, maximum thickness 120 m) which runs from
about 1200 m down to 600 m elevation.
The central glacier region follows the water
divide from west to east along the Icelandic central
highland. Several ice caps mantle the highest
mountains such as Thórisjökull, Eiríksjökull,
Langjökull (953 km2), Hrútafell, Hofsjökull (925
km2), Tungnafellsjökull and the mountains Bárd-
arbunga, Kverkfjöll and Grímsfjall in the northern
part of Vatnajökull (Fig. 1). The ice cap Snæfells-
jökull may also be included in the region. The
northern outlets in the central region terminate at
high elevations, above 800—900 m. The southern
outlets of Hofsjökull and Langjökull flow down to
700 m and 600 m, respectively.
The southern glacier region follows the southern
and southeastern coast of Iceland. The region in-
cludes the ice sheets Tindfjallajökull and Torfa-
jökull and the ice caps Eyjafjallajökull, Mýrdals-
jökull (596 km2) and the southern part of Vatna-
jökull where the main glaciation centres are Ör-
æfajökull, Esjufjöll and Breidabunga (Fig. 1).
Small cirque glaciers are found in the Eastern
Fjords, mainly east of Vatnajökull. Several outlet
glaciers from Vatnajökull and Mýrdalsjökull ter-
minate below 150 m elevation and extend into
country which has been inhabited ever since the
first colonization of Iceland.
The central and the southern glacier regions
74 JÖKULL 29. ÁR