Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 59

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Tjörnes. Bárðarson thinks that the sediments continue into
the lower part of the monntain Ólafsvíkurenni (419 m) which
seems very probable. This mountain consists of moraine and
loess at the base, covered by fresh, normally magnetized co-
lumnar breccias, the summit being formed by several lava
flows. According to Pjeturss older basalt with eastward dip
crops out on the west side, the breccia here resting on a mo-
raine. Pjeturss seems to consider the Ólafsvíkurenni as an
erosional remnant of a large Pleistocene Snæfellsjökull vol-
cano.
At the shore east of the Ólafsvík village is old very much
infilled basalt. Finally we mention that Krossnes east of
Brimlárhöfði is made of a normally magnetized, relatively
young lava which occurs in a zone south to Hálsvaðall and
is separated from Brimlárhöfði by low terrain with marshes.
The island Melrakkaey is probably made of the same lava.
This volcanism may be comparable with the dolerite between
Grísará and Berserkjahraun, i.e. the Kerling volcano.
3. Erosion stages. Remnants of a low rock terrace are seen
on the north side of the peninsula west of Grundarfjörður,
although not especially clear. There is a low rock plain be-
tween Brimlárvellir and Búlandshöfði, cut into older basalts.
But on the south side of the peninsula a strandplane is espe-
cially clear, being many kilometres broad. This is a true
rock terrace; it cuts e.g. gabbro in Stekkshóll near Vatnsholt,
and solid rock crops out in numerous scerries along the shore.
The contrast between the north and south sides is so marked
that there must be a special cause. This is probably found
in the prevailing southerly winds. Another feature is also
related to this, namely that valley development is much more
advanced on the north side. The reasonable cause of this is
that marine erosion in the south, the strandplane develop-
ment, has wiped out the corresponding dissected southern
stretch of the peninsula. As a result of this marine erosion
we have a sharp drop from a 300—600 m high edge down
to the strandplane, while in the north such a drop occurs