Rit (Vísindafélag Íslendinga) - 01.06.1967, Page 183

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Thorleifur Einarsson: It should be stressed that the tec-
tonic structure of Iceland is by no means a dilatation struc-
ture, and that all kinds of faults exist in Iceland. Up to now
the structures have not been studied thoroughly, but normal
and reverse faults as well as lateral faults (strike - slip faults)
exist. It is not true that only phenomena which indicate dila-
tation are observed in the neovolcanic zone as can be seen
from the Tjörnes-horst at the western margin of the neo-
volcanic zone in N-Iceland. This horst has been tilted and
uplifted more than 600 meters in the last million years.
Trausti Einarsson: The Tertiary basalts are mostly at a
shallow depth in central parts of Iceland. In the area around
Hofsjökull they are about 300 m under the surface, as ob-
servations in the Skagafjördur valleys indicate and as con-
firmed by seismic studies of G. Pálmason. At the head of
Bárdardalur the plateau basalts dive under the lavas of Ódáda-
hraun at a height of about 700 m above sea-level, with hard-
ly any dip. They probably remain nearly at this level all
through to the basalt area of eastem Iceland, as might be test-
ed by seismic methods. This picture of the basalts in the cen-
tral areas I first presented in 1946 (Origin of the Basic Tuffs);
it is widely different from the well-known older picture given
by Bárdarson. In connection with the origin of the main Bou-
guer bowl, I have spoken of plastic movement at depth. For
this process I have not dared use the term folding, but I rather
favour its introduction into Icelandic geology if it is used
carefully and with qualification.