Jökull - 01.12.1970, Síða 78

The interglacial non tilted lava flows have
normal magnetization whereas several reversals
occur within the underlying Hreppar Series.
With regard to their position and freshness the
young lavas most reasonably belong to the
present normal polarity epoch (Brunhes) giving
a maximum age of 690,000 years (Cox 1969).
The degree of erosion of the interglacial lavas
is the only available means to estimate their
minimum age. The area was overridden by a
main glacier throughout most of the last glacia-
tion (Kjartansson 1943, 1958) which has un-
doubtedly resulted in an enormous glacial ero-
sion during this period. The present writer finds
it possible that the olivine basalts south of
Thjórsá were erupted cluring the last inter-
glacial period. On the other hand the tholeiites
are believed by the writer to date back from an
earlier interglacial period.
ACKNOWLEDGEMENTS
The ivriter is indebted to G. E. Sigvaldason
for his help in X-ray work on the zeolities, to
H. Tómasson and J. Jó?isson for useful discuss-
ions. He wishes to thank Prof. M. Schivarz-
bach and G. Pálmason for co?istructive critic-
ism of the manuscript and Peter Ward for
lingustic improvements and useful comments.
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