Jökull - 01.12.1966, Page 3

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JOKULL
Á R S R I T
KLARAN N SÓ KNAFÉ LAGS ÍSLANDS
TRAUSTI EINARSSON1:
Late- and Post-glacial Rise in Iceland
and Sub-crustal Viscosity
It has been known for some time that the
rise of Iceland at the end of the Last Ice Age
was relatively rapid, when compared with the
rise of Scandinavia, being largely completed in
a few thousand years. On this basis I have
made the rough estimate that subcrustal vis-
cosity for Iceland is one order of magnitude
iess than that for Scandinavia (Einarsson 1953).
As the value found for Iceland is probably
representative for a considerable part of the
Middle Atlantic Ridge, emphasis should be laid
on obtaining this value with more certainty. A
new approach has been rnade possible through
a number of new data. The procedure in the
present paper is aimed at finding a relative
value, with Scandinavia as a standard. At the
same time a general picture of the rise in Ice-
lancl is obtained.
The relative value of viscosity now found
1) Faculty of Engineering, University of Ice-
land, Revkjavík.
for Iceland is a iittle less than one tenth, i.e.
close to the earlier estimate.
In a first section we consider generally the
changes of sea-fevel in unglaciated areas. Then
we summarize relevant facts about Scandinavia,
and finaliy discuss the Icelandic material and
compare it with the Scandinavian one, Re-
marks on glacial sea-levef in the Faeroe Islands
are added.
1. UNGLACIATED AREAS.
The rise of late- and post-glacial sea-fevel
relative to coasts far awav from the glaciated
regions has been studied by many authors. We
shall use here data given by Fairbridge (1960,
1961), curve Si in Fig. 2, and for comparison
data by Godwin et. al. (1958), curve S2 in the
same figure.
In connection with the application of such
curves, it is necessary to consider the possible
isostatic movements of the ocean floor and
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JÖKULL 157