Jökull - 01.12.1985, Blaðsíða 27

Fig. 16. Marine erosion of talus cones at Kögur, proba-
bly indicating a presently rising sea level. 16. mynd.
Sjávarrof á skriðukeilum undir Kögri, sem bendir til
áflœðis.
evidence from Hornstrandir, in a peripheral position
with regard to the Vestfirdir peninsula, suggests that
during the Weichselian glaciation the high plateaux
were not covered by active glaciers, as no signs of glacial
erosion or deposition were found there. Possibly the
plateaux were covered by thin, inactive and/or cold
based glaciers or firns. Using the maximum value for
the thickness of active glaciers, an approximation of
their maximum horizontal extent leads to the conclusion
that during the Weichselian maximum glaciation they
could not have extended more than some 6-10 km off
the present coast. We suggest that two concentric zones
of shallow banks at the entrance to Adalvík may be of
glacial origin, and that the outermost bank possibly
represents the Weichselian maximum position of the ice
front. According to our concept the ice extent here,
during the Weichselian maximum, was much more
limited than proposed by Andersen (1981). The nuna-
taks, plateau edges and slopes could probably have
provided some refuge for plants and animals.
(2) During deglaciation the sea level reached 26—15
m higher than today. Morphological and stratigraphical
evidence shows that the general retreat of the glaciers
was interrupted by a readvance before final deglaciation
of the area. Despite extensive search we did not find
any organic material to absolutely date the deglacia-
tion, but on the basis of analogy with other areas in
Iceland, we propose that the readvance occurred during
the Younger Dryas period.
(3) Shortly after the final deglaciation, a heavy influx
of basaltic tephra took place. This tephra, the Haelavík
Time B.P. Extent of glaciation Sea level. ELA, m lce covered Comments
0 100 200 I I I rising >500 í 300-350 {<500 1-1.5 8-10
9000- 10000- I I I \ S 0 15 26 rising < 150 > 400 Haelavik tephra
? 18000- \ \ \ \ \ \ \ > None Medium Slight Extensive l < 150 > 800 Nunataks ♦ unglaciated outermost shelf
Fig. 17. Summary of our results concerning the glacial
history and sea level changes on Hornstrandir. 17.
mynd. Samantekt yfir niðurstöður okkar um jöklunar-
sögu og sjávarstöðubreytingar á Hornströndum. Jöklun-
armörk (ELA) eru fundin með samanburði á botnhœð
hvilfta með og án jökla.
tephra, will be a scope of a separate study as it could
constitute an important marker horizon, if found in
connection with dateable material elsewhere. The
tephra could also open the possibility to link the Horn-
strandir record with the deep-sea record, as important
deep-sea cores with tephra horizons have been taken
from the surrounding seas (Kellogg 1980, Kellogg et al.
1978, Ruddiman and Mclntyre 1981). Efforts are being
made to extend the well dated tephrochronological
record back to Late Weichselian time, to allow for
correlation of marine and terrestrial data (Mangerud et
al. 1984).
(4) During the Little Ice Age, glaciers were re-estab-
lished in 7—10 cirques on northern Hornstrandir, with a
total glaciated area of 8-10 km2. The ELA in the
glaciated cirques varied with exposure, between 300 and
500 m above present sea level. There were no glaciers
on western Hornstrandir during the Little Ice Age.
Today, four cirques on northern Hornstrandir contain
small glaciers, with a total area of maximum 1.5 km2.
Lichenometric studies at one site indicate that the maxi-
mum extent of the Little Ice Age glacier there was
reached around or before AD 1860 and that the glacier
had almost disappeared by AD 1920.
(5) Coastal erosion of talus cones and of lacustrine/
fluvial sediments is interpreted as indicating that sea
level has risen in comparison with earlier parts of the
Flandrian. This is in contrast to Tr. Einarsson (1946,
JÖKULL 35. ÁR 25