Rit (Vísindafélag Íslendinga) - 01.07.1962, Side 53

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53
a considerable thickness of rocks has been eroded away above
the summit level.
At 440 m there is a 3 m thick conglomerate resting on an
unworked lava surface. The topmost third part of this layer
is very moraine-like, but other signs of glacial work are absent.
This is a type of grey conglomerate often found in the upper-
most parts of the Plateau Basalts, e.g. around Hvalfjörður.
It may indicate frost action (cryoturbation) but not neces-
sarily a glaciation, unless corroborated by a clearer evidence.
Above this conglomerate there is some volcanic breccia and
kubbaberg.
In Mýrarhyma (along the river Kirkjufellsá) we can fol-
low the Young rocks above an elevation of about 200 m. At
several levels there are conglomerates and gravels. Thus at
475 m a very coarse conglomerate with rounded blocks up to
1 Yz m in diameter. The highest conglomerate level was found
at 585 m. At 450 m is a moraine-like conglomerate, and above
this level the lavas are mostly of the blocky or kubbaberg
structure.
We find then, generally, that the lower part of the reverse
group, with a thickness of about 250 m, is built up of usual
lava flows while above a certain level, marked by a “tillite”,
the character changes to the blocky and partly brecciaceous
type. This type prevails to the top of the group in Mýrar-
hyrna, to a level of about 800 m. Here these rocks are cut
by a west-dipping erosion surface on which the normally
magnetized rocks rest: first a horizontal lava, followed by
kubbaberg and globular breccia, then coarse primary tuff
and, finally, many thin lava flows reaching the surface of
Kaldnasi (986 m).
The reverse group extends below the Helgrindur ridge to
the south side of the Snæfellsnes peninsula and is well ex-
posed below the Kambur ridge, north of Böðvarsholtshyma.
Below the NE-corner of Kambur we have a lava series from
430 m to 530 m belonging to the lower part of the reverse
group. This is covered by a moraine-like conglomerate which