Jökull - 01.12.1983, Blaðsíða 98

smaller glacier thickness in the southern highlands
than in the central ones.
One of the characteristics ofalpine glaciers is that
nunataks are usually associated with them as well as
ice free slopes and spurs. It is thus likely that this
has been the case in Iceland in previous glacial
periods, and indeed this viewpoint agrees well with
research by some botanists, as Steindór Sleindórsson
(1954, 1962) on those places whereplants have held
out and survived previous glacial periods, even-
though it is questioned by some others (Sturla Frið-
riksson 1962). Itcould besaid that in all alpine areas
it is possible to fmd some plants having a limited
distribution. In addition the opposite could be said,
that all plants having a limited distribution can be
found associated with alpine areas. I believe all the
evidence points towards there having been ice free
areas on promontories and slopes along the coast,
not only during the last glaciation but throughout
all of the Quaternary Era.
The age of the interglacial lavas in Vídidalur
(.Koerfer 1972) and Quaternary formations in Lón
and Hornafjördur (Helgi Torfason 1979) suggest that
valley development has been well advanced at least
a million years ago. I think this indicates that the
main features of the landscape and possibly the
continental shelf had already been formed early in
the Quaternary or even to some extent before the
end of the Pliocene period.
In glacial periods there would always have been
many ice centres in Iceland with the main ice divide
between the north and south ílowing glaciers close
to the present water divide and glacier thickness
would not have been much thicker than that of
Vatnajökull today, generally 200-800 m but possi-
bly up to 1000 m in deep valleys.
Time does not permit discussion of the conditions
of glacier formation in previous glacial periods.
Examination of those weather maps most likely to
compare with the prevailing climate in glacial peri-
ods (Lamb 1977), suggest that all precipitation was
considerably less especially in southem and south-
eastern Iceland, where the prevailing precipitation
direction was northeasterly to northerly. They
could have been comparable with those prevailing
in October to December 1981.
ACKNOWLEDGEMENTS
I wish to thank Freysteinn Sigurdsson as well as various
other colleagues for many very useful suggestions and dis-
cussions on the material and conclusions of this paper.
Thanks are due to George R. Douglas, Ph.D. for the
English translation of the present paper.
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