Jökull - 01.12.1978, Page 31

north of it. To the south of HofsjökuII it is
1200—2000 mm/year and 600—800
mm/year at the north side (Sigfúsdóttir 1976).
There is no reason to expect the main rain-
carrying wind direction to have been mark-
edly different in Glacial and Lateglacial time
from the present one. At that time the main
ice sheet was much more extensive than the
glaciers of today. The northern winds were
much dryer than they are today because of a
widespread sea ice cover to the north of Ice-
land. Consequently the difference in
precipitation between northern and southern
Iceland was still greater in Glacial and Late-
glacial time than it is now.
On the base of tephrocronological studies
Thorarinsson (1956 and 1964a) has proved that
2500 years ago, some small, steep glaciers on
high mountains reached their maximum ex-
tent. These glaciers are supposed to have exis-
ted before the climatic deterioration. Like all
the large ice-caps in Iceland, the present
Hofsjökull is supposed to have started to form
during the cold period that began 2500 years
ago, i.e. in Subatlantic time. The ice caps did
not reach their maximum extent until about
1890. Since about 1920 Hofsjökull has
retreated constantly along the north margin
except for a small tongue northwest of Mikla-
fell (Fig. 1).
The main problem encountered in these
investigations was to determine the age of the
end moraines. As pointed out earlier, the
vegetation in this area is very sparse, so
material for dating of the moraines is com-
pletely lacking. Down in the valleys it should
be possible to find marine shells from a higher
sea level, but in spite of intensive searching no
shells have been found (Víkingsson 1976).
The ice is supposed to have retreated from
the Skagafjördur valleys in Alleröd time
(■Einarsson 1967, Víkingsson 1976, 1978). There-
fore, two possibilities can be considered as to
the age of the moraines north and northeast of
Hofsjökull: 1. The Raudhólar moraine dates
from Younger Dryas and the seven others
from Pre-Boreal time. 2. No remnants of the
end morains from Younger Dryas are left in
this area, and all eight moraines are of Pre-
Boreal age. At this stage it is not possible to
decide which one of these two statements is
true. The only possible solution of this pro-
blem is to correlate this area with other inves-
tigated areas which is a task for future studies.
ACKNOWLEDGEMENTS
The field work on which this paper is based was
mostly carried out in the summers 1974 and 1975,
partly in connection with hydropower investigations of
the National Energy Authority (N.E.A.), andpartly
for a Cand. Real. thesis at the University of Bergen
(Kaldal 1976). The work was financed by the
N.E.A. and the University of Bergen. The author
wishes to express her special gratitute to Professor
Björn G. Andersen at the University of Bergen and
Professor Thorleifur Einarsson at the University of
Icelandfor their interest and guidance during the field
work and preparation of the thesis, and also to all
others who have contributed to the work by inspiring
discussion.
REFERENCES
Einarsson, Th. 1967: Zu der Ausdehnung der
Weichelzeitlichen Vereisung Nordislands.
Sonderveröff. Geol. Inst. Univ. Köln 13:
167-173.
Kaldal, I. 1967: Kvartærgeologiske undersök-
elser i omrádet nord og nordöst for Hofs-
jökull, Nord-Island. Unpublished
Cand.Real. thesis, University of Bergen, 92
pp.
Kaldal, I. and S. Víkingsson 1978: Jökulsár í
Skagafirði. I. Jarðfræði. Orkustofnun raf-
orkudeild, OS-ROD-7805, 33 pp.
Kjartansson, G. 1943: Árnesinga Saga. Yfirlit
og jarðsaga. Reykjavík, Árnesingafélagið.
250 pp.
Kjartansson, G. 1955: Fróðlegar jökulrákir.
(Studies on glacial striæ in Iceland). Nátt-
úrufræðingurinn 25: 154—171.
Kjarlansson, G. 1965: Jarðfræðikort af Islandi.
Blað 5, Mið-ísland. (Geological Map of
Iceland. Sheet 5, Central Iceland) Reykja-
vík, Menningarsjóður.
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