Jökull - 01.12.1989, Page 31

i. The ice-scraped Reykjavík olivine tholeiite basalt
forms the base of the unit.
ii. On top of it lies till from the later part of the Iast
glaciation (perhaps from the Older Dryas).
iii. Next in the succession is a shell-rich marine sed-
iment, with a record of the Alleröd Interstadium.
It shows that the ice had retreated behind the
present coast. The sea transgressed the Reykjavík
area and a multifarious shell fauna flourished by
the coast.
iv. A till layer covering the fossiliferous sediments
indicates the advance of the Younger Dryas gla-
ciers 11,000-10,000 years BP. At this time, the
whole of the Reykjavík region was covered by
glacier.
v. Late in the Younger Dryas or early in the Prebo-
real period, the glaciers retreated behind the
present coast line. Their last advances deposited
the end-moraines at Alftanes and the moraine
group at Kópavogur.
vi. The sea transgressed again, and a new series of
shell-bearing layers were formed. During this
period the sea level rose to 40-50 m above present
level forming the old coast line at 43 m elevation
a.s.l. on Öskjuhlíð.
vii. This is now covered with soil, concrete and
asphalt, clear indicators of a geological period,
which is still to be named, where the activity of
man competes with the power of ice and fire in
modifying the surface of the Earth.
The radiocarbon dates on the Fossvogur layers
lead to a revision of the geological history of
Reykjavík and the nomenclature of the Quaternary
in Iceland. The names Fossvogur Interglacial as a
synonym for the Eem Interglacial and the Alftanes
stadial as a synonym for the Older Dryas should not
be used any more.
ACKNOWLEDGEMENTS
I wish to express my gratitude to the Icelandic
Science Fund for financing the radiocarbon age
measurement of Lu-2599; the staff at the accelerator
mass spectrometry facility at the University of
Aarhus, Denmark, for their isotopic measurements
and for valuable cooperation; Sigfús Johnsen and
Arný Erla Sveinbjörnsdóttir for their kind coopera-
tion in the dating work; Dr. Kristján Sæmundsson
and Dr. Halldór G. Pétursson for helpful comments
on an earlier draft of the manuscript; Tómas
Jóhannesson for helpful editorial advice; Dr. Páll
Imsland for his moralistic and orthodox criticism;
Auður Ágústsdóttir and Gyða Guðmundsdóttir for
the drafting work; Ómar Bjarki Smárason and Páll
Ingólfsson for the English translation.
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