Acta naturalia Islandica - 01.02.1946, Page 44

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TRAUSTI EINARSSON
ary phase of eruptions of a certain type. As will be more clearly
seen later there is every reason to pay especial attention to this type
of volcanism when studying the volcanism of Iceland. Yet, it must be
kept in mind that these conglomerates, interpreted as moraines, have
played a dominant role in Icelandic geology for a long time. We shall
therefore have to consider directly some well-known localities of the
supposed moraines.
6. HVÁLFJÖRÐUR
This area in S.W. Ieeland presents many interesting and important
features. Above all the conception of a non-glacial origin of the grey
conglomerates can here be put to a very hard test, perhaps the
hardest test it is likely to be out for.
Here, at the head of Hvalfjörður, near to the farm Botn are to
to be found two of Pjeturss’ classical localities of “Early Quaternary
Moraines”. They were discovered and described by Pjeturss in
190421).
In these localities the morainic nature of the described conglom-
erates is, it seems, especially convincing for the reason that not only
did Pjeturss find striated stones in them, but the conglomerates in
Austurgil and at Glymur, he reports, rest on a very clearly striat-
ed floor of basalt.
We shall now pay special attention to the sections which contain
these interesting conglomerates. I had no difficulty in finding either
of these sections from Pjeturss’ description.
The section in Austurgil. Below a thick pile of grey fine-grained
porphyretic basaltic lavas we have the section shown in Fig. 3 (c.f.
Pjeturss’ Fig. 6, l.c.).
The section is as follows:
1. Dark amygdaloidal basalt.
2. A dark conglomerate in an advanced state of decomposition.
I could not find any glacially striated stones and I think that in
this state of the conglomerate it is impossible with any safety to de-
cide upon glacial striation of the contained rounded stones.
Pjeturss reports that striated stones are easily found, which is
contrary to my observation and I cannot accept his interpretation of
this conglomerate as a moraine.