Jökull - 01.12.1990, Page 97

arfjörður and Hvalfjörður regions, W-Iceland and on
Melrakkaslétta in N-Iceland. These sediments demon-
strate that at that time (Bölling) the climate had im-
proved considerably so that parts of Iceland were ice-
free and due to melting of glaciers the sea level had
nsen and transgressed on land that was left suppressed
by the weight of the glaciers. Alleröd-age marine sed-
iments from the Reykjavík region, Hvalfjörður and
Borgarfjörður demonstrate further improvement of the
climate. No marine sediments have however been ob-
served with certainty of Younger Dryas age, despite
considerable search. The lack of shells from that time
mdicate severe glaciation of the country in the Younger
Dryas period. In addition to this evidence for the Late
Weichselian oscillations, é180 measurements on shells
from late glacial sediments of known age in S and W
Iceland suggest similar temperature-pattem to that re-
vealed by the isotopic composition of the Greenland
ice and the lake sediments from Switzerland.
acknowledgement
Radiocarbon dating projects are currently in
progress in cooperation with Jan Heinemeier and Niels
Rud at the tandem accelerator laboratory, University
°f Aarhus. We thank them for allowing us to use un-
published data on Icelandic molluscs. Some of the ra-
diocarbon dates are parts of projects done in coopera-
tion with Icelandic geologists Ámi Hjartarson, Áslaug
Geirsdóttir, Hreggviður Norðdahl and Jón Eiríksson.
We acknowledge the use of this data for the purpose
°f the present paper. We would also like to thank Karl
Grönvold at the Nordic Volcanological Institute and
Jón Eiríksson at the Science Institute, University of
Iceland, for critically reading the manuscript and for
utany valuable suggestions.
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