Rit (Vísindafélag Íslendinga) - 01.07.1962, Side 105

103
Perhaps the lowest memher seen in the mountain slope is
found at point III, Fig. 54, km from the outcrops on the
lowland and 70 m higher. We have here two horizontal lavas
(n0) of which the lower has clear normal polarization. The
lava is much filled with onyx, usually a sign of rather high
age in Iceland. The two lavas are separated by a 30 cm hrown
sediment. The polarity of the second lava is uncertain. This
lava is covered with dehris, 2—3 m thick, probably weathered
out of the lava. Then there is a conglomerate, probably flu-
viatile, but also containing windblown sand. On this sediment,
which is hard and considerably cemented with white infil-
lings, rests basalt of reverse polarization (r2). At 190 m this
basalt is covered by a conglomerate, covered in turn by a suc-
cession of some 5 normally polarized basalt lavas (nT), which
are of fresh look and nearly devoid of infillings. At 215 m we
have an undoubted grey moraine (m2) several metres thick,
then brown windblown tuff (70 cm), a coarse primary nor-
mal breccia (1 m), a brown secondary tuff, a primary nor-
mal breccia (50 cm), a secondary brown tuff (1—2m) and
finally a thick primary normal breccia (n2) which forms all
the higher part of the whole mountain. It is possible that
a moraine mT and the group rT are older than n0 but this
is uncertain.
The moraine mT is clear in I and V, resting on the altered
reverse breccia rT. This moraine has been deposited on an
erosional surface below which the rocks are usually much
altered. This is especially evident at the westem end of the
section where below mT there is a heavily altered primary
breccia which is in striking contrast to the quite fresh rocks
above mT (Silfurberg is silvery grey from calcite and zeolites).
It seems reasonable to assume here a considerable gap in the
record. The lower rocks which must rest on the erosion plane
on the dipping Plateau Basalts, comprise visibly two magne-
tic groups, n0 and rT. It seems probable that these are the
equivalent of the groups below about 270 m in the southem
Vörðufell. The moraine mT may then correspond to the mo-