Jökull - 01.12.1983, Blaðsíða 95

don‘t believe there is any reason to question the fact
that the strandline in Iceland has been somewhat
lower than today in former glaciations. However I
consider that there is no reason to assume a large fall
in sea level, since it is fairly certain that the Iceland-
ic crust is so weak and flexible, that its isostatic
sinking under ice pressure takes a very short time
compared with the continents. It is even possible
that at certain times isostatic sinking has been so
much in certain areas, that the sea level has been
higher than it is today. On the other hand it would
hardly be likely, that the extensive marine erosion
along the coast of the country has occurred during
glacial periods themselves, except to a small degree.
It is considered well proven tliat sea level was
considerably higher during interglacial periods of
the Quaternary Era than it is today, and still more
so towards the beginning of the Quaternary Era.
Holmes (1965) believes sea level to have fallen nearly
200 m in the last 2 million years (p. 713), and
Woldstedt (1961) reaches a similar conclusion (p.
374). He believes that sea level has been almost 20
m higher during the last interglacial and 30 m high-
er in the second last interglacial.
VVhen it is borne in mind that the majority of
promontories and wave-cut cliífs belong to the alp-
Fig. 6. Hvalsnesskridur are wave cut clifFs with a
strandflat beneath such as is most common on
coastal promontories in western Iceland, southern
Iceland and the eastern fjords south of Gerpir. In
the distance the promontories of Streitishvarf and
Kambanes can be seen. — Photo G. Sigbj.
Mynd 6. Hvalsnesskribur eru brimklif með strandjleti fyrir
framan eins og algengast er með sjávarmúla á Vestur-
landi, Suðurlandi og Austfjörðum sunnan Gerpis. í
jjarska sjást múlarnir Streitishvarf og Kambanes. —
Ljósm. G. Sigbj.
Fig. 7. Glacially grooved outcrop south of the
farm Sledbrjótur in Jökulsárhlíd. Sinous glacial
grooves are called “cavettos” and together with
smoothed outcrops they are indications of erosion
by a thick glacier.
Mynd 7. Jókulgrópuð kl'ópp sunnan við bœinn Sleðbrjót í
Jökulsárhlíð. Bugðóttar jökulgrópir eru nefndar „cavetto“
og eru ásamt mjóg ávöluðum klóppum merki um rof eftir
þykkan jökul. — Ljósm. G. Sigbj.
ine landscape and that it is likely thatglacial erosion
at the coast was limited during the last glaciation, it
seems obvious to conclude that the fjords promont-
ories and wave-cut clifTs have been formed largely
during the interglacial periods of the Quaternary
Era.
GLACIAL EROSION AND FLUVIAL
EROSION
By comparing Figs. 2 and 3 the enormous differ-
ence in the large scale landforms of the landscape
formed by alpine glaciers on the one hand and by
JÖKULL 33. ÁR 93