Jökull - 01.12.1985, Blaðsíða 12

Fig. 1. Location map for Northwestern Iceland, indicat-
ing places mentioned in the text which are located
outside the study area on Hornstrandir. 1. mynd. Stað-
setningarkort fyrir Hornstrandir.
one week in July 1983 CH and ÓI studied the Haelavík-
Hlöduvík area on the north coast.
Altitudes at sections along the coast were measured
with hand level and/or measuring tape, those inland
with a Paulin altimeter. The high water mark was used
as base level. Chronostratigraphical terminology is
according to Mangerud et al. (1974) and, as regards the
Weichselian, Mangerud and Berglund (1978).
General geology and morphology
Hornstrandir is a dissected Tertiary basalt plateau, its
bedrock being at least 14 million years old (Th. Einars-
son 1968, Kjartansson 1969, Símonarson 1979,
Saemundsson 1979). The general topography of the
area and the more important place names used in the
text are shown in Fig. 2. Around Adalvík in the west the
plateau surface lies around 400 m. It rises towards the
east and gets more and more dissected in that direction.
In the rugged 700 m high mountains south of Hornvík
not much is left of the original plateau surface.
The valleys on Hornstrandir are rather short, the
longest being the one inside Fljótavík — 8 km long and 3
km wide at the entrance. They are all glacially sculp-
tured. A characteristic feature of the landscape are the
cirques. These occur either single or as composite ones.
The short and relatively wide valleys often end with
rather broad coastal lowlands. Inside Adalvík, Fljótavík
and Hornvík these are about 2 km wide.
The shelf around Hornstrandir is rarely deeper than
about 100 m and the 50 m depth curve lies about 5 km
off the coast in the west and northwest. It comes closer
only off Hornvík, where a northwest trending basin,
overdeepened by some 50 m and with depths down to
105 m, reaches into the bay.
The general pattern of short, steeply ending valleys
with well developed cirques indicates that glaciation on
Hornstrandir was of a predominantly local character.
Present climate
Both according to the mean air temperature in July
and the temperature of the sea, Hornstrandir lies within
the low-arctic zone (e.g. Freuchen and Salomonsen
1959).
The climatic tree-line probably runs somewhere
through central Hornstrandir (E. Einarsson 1975). At
present there are two meteorological stations close to
Hornstrandir and with similar exposure, one at Galtar-
viti south of the entrance to ísafjardardjúp, another at
Hornbjargsviti immediately east of Hornbjarg (Fig. 1).
Recorded annual mean temperatures at Galtarviti and
Hornbjargsviti are +3.8°C and +3.1°C, respectively,
with the highest monthly mean temperatures in August,
+9.6°C and +8.2°C, and the lowest in February, -0.8°C
and —1.1°C (M.Á. Einarsson 1976). Annual mean pre-
cipitation values at Galtarviti and Hornbjargsviti have
been recorded as 1265 mm and 1373 mm, respectively.
The prevailing wind direction on Hornstrandir is prob-
ably from the northeast.
Permafrost occurs on the high plateaux. On Fljóts-
heidi east of Látrar, 450-500 m above sea level, ice was
encountered at a depth of 15-30 cm on 23rd of July
1982. Large stone polygons and stone stripes are
common.
WEICHSELIAN GLACIATION AND
MARINE LEVELS
Research history
The Icelandic geologist Thorvaldur Thoroddsen,
travelling on Hornstrandir during the summers 1886 and
1887, made numerous observations on its geology and
morphology (Thoroddsen 1892a, 1892b, 1906). He rec-
ognized that the whole landscape of the Vestfirdir
peninsula is characterized by glacial erosion, and he
observed glacial striae and glacial deposits at numerous
localities. From a monoglacialistic point of view, he
concluded that during „the Ice Age“ the area had been
covered by an extensive ice cap, which he considered to
have been independent of the main Icelandic ice sheet.
He estimated the thickness of this ice cap to 400—500 m,
and assumed that outlet glaciers from it had extended
into the valleys and fjords. He noted the absence of
submarine valleys on the shallow banks off the Horn-
10 JÖKULL 35. ÁR