Jökull - 01.01.2009, Blaðsíða 21

Chemical and mechanical fluvial denudation in cold environments
Figure 2. The Hrafndalur catchment, Eastern Iceland. – Hrafndalur, Borgarfirði eystra.
sculptured relief is Alpine and lithology is dominated
by rhyolites. Soil cover on rhyolite is thin or lack-
ing due to frequent denudative slope processes and a
high mobility of the weathered rhyolites. Vegetation
includes lichens, mosses meadows, bogs and dwarf
shrubs (Beylich and Kneisel, 2009).
The Kidisjoki catchment (69◦47’N, 27◦05’E; 18
km2; 75–365 m a. s. l.) is situated in the sub-Arctic
Kevo region in northernmost Finnish Lapland (Fig-
ures 1 and 3). The Kevo region is geologically part
of the Baltic shield, and the bedrock consists mainly
of resistant gneisses and granulites. The dominant
mineral soil is glacial till (Okko, 1960), consisting of
poorly sorted sand and silt with a high abundance of
gravels. It is mostly covered by younger biogenic de-
posits and, over larger areas, by thin layers of forest
humus or by varying thicknesses of sedge and moss
peat. Clay deposits are mostly absent due to the supra-
aquatic conditions following the continental ice melt.
The cool climate and acid soil create favourable con-
ditions for podzolisation. The climate of northern
Fennoscandia is oceanic (Lloyd et al., 1999). The
mean annual precipitation in Kidisjoki is 415 mm
yr−1 and between 30 to 40% of the total precipita-
tion at Kevo is summer rainfall (Beylich et al., 2006b).
Thickness of the winter snow cover can vary consid-
erably from a general average of 0.5–0.8 m, which
tends to reach a maximum at the end of March before
snowmelt begins. Snow cover has usually disappeared
by the end of June. The first snow falls in September
and continuous snow cover normally forms in the be-
ginning of October. Appart from some palsa mires in
the upper part of the catchment, there is no sporadic
permafrost in Kidisjoki. Reindeer grazing is signifi-
cant in the area.
The mountain area of northernmost Swedish Lap-
land is located close to the North Atlantic in a pre-
vailing westerly wind regime. The Arctic-oceanic
climate in Latnjavagge (68◦20’N, 18◦30’E; 9 km2;
950–1440 m a. s. l.) (Figures 1 and 4) is charac-
JÖKULL No. 59 21