Acta naturalia Islandica - 01.02.1946, Page 46

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TRAUSTI EINARSSON
coarser grain, angular shape of the glass fragments, ancl the pre-
sence of worn grains of lava. It is the dominating brown palagonite
that determines the colour.
These sediments are covered by a number of grey, fine-grained,
porous lavas of basalt.
These strata as a whole do not suggest a glaciation. They are
simply a volcanic series like those described in the previous chapters.
A striated floor of the conglomerate (4) can hardly change that
conclusion. Yet, we shall consider this striation closer.
The surface of the lava (3) is very clearly filed as stated by
Pjeturss, elongated grooves and striae are unmistakable and there
is much resemblance to a glacially filed surface. Also, there is no
doubt that this surface goes under the conglomerate.
On the other hand the conglomerate does not lie directly on the lava
surface (cf. Fig. (4) which is a section at right angle to the striae).
The surface of the lava is covered with a 1 cm thick layer of soft
yellowish clay. Then comes a loose mass of fragments of a hard
brown amorphous or glassy substance, evening out the grooves of
the lava surface. The lower surface of the conglomerate that rests
on this loose mass consists of the same amorphous substance.
5cm,.

Fig. 4. — Lower contact of grey conglomerate in Austurgil. See text.
I cannot see any possibility of accepting this as the contact of a
moraine and its floor. On the other hand the interpretation of this
contact is far from being clear. This much is clear that the grooves
of the lava-surface were filled up before the deposition of the con-
glomerate and it seems most probable that the high temperature
of the mudflow, which in my opinion, the conglomerate represents,
metamorphosed the underlying sediments.
The section at Glymur. Fig. (5) is a reproduction of Pjeturss’
Fig. 4 (1. c.) showing the section at the waterfall Glymur. It shows
a series of alternating basaltic lavas, brown tuffs, and conglomer-
ates. Only the highest part of the section is accessible to close ob-