Rit (Vísindafélag Íslendinga) - 01.07.1962, Blaðsíða 54

54
in turn is overlaid by a thick primary breccia. This seems
to be the boundary between the two parts of the reverse
group. Higher in this section, at about 600 m we find conglo-
merate, fine sand, and red bumt clay covered by a reverse
lava. Undoubted leaf impressions are seen in this clay but
they are in no good condition, being too close to the lava floor.
This lava and a few more have been deposited in an ero-
sional depression in the sediments.
At 660 m there is a grey conglomerate with scattered very
large boulders, up to 1V2 m across. This might be compared
with the conglomerate found at 475 m in the Mýrarhyrna
section. The conglomerate is covered by a reverse columnar
lava, on whose eroded and weathered surface — covered with
a thin layer of pebbles derived from the lava — rest normal
lavas. The pebbles in contact with the lowest normal lava
are also normally magnetized.
This is a series of thin lavas and thin tuff layers, which
have flowed down a slope towards NE. These lavas are cover-
ed by a primary breccia which forms the highest part of the
Kambur ridge. The normal rocks have here been deposited
on an erosional surface cutting the reserve group. This sur-
face rises in general northwards and we can trace the reserve
group to a height of about 800 m at Tröllkerling. At the up-
per contact we have a 5—6 m thick tillite with clearly stri-
ated boulders, deposited in a west-dipping slope, and on this
a kubbaberg with normal magnetization. A little higher is
a young crater which must be much younger than the main
mass of normal rocks.
The reverse group grows thinner towards the west because
of erosion, and is not found at Fróðárheiði. Also towards Bú-
landshöfði there is much erosional thinning. To the east of
Helgrindur I have not traced the group but it seems to be
represented in Grundarmön by horizontal lavas of reverse
magnetization above the 290 m-level. The group has a pro-
nounced plateau character and it must be assumed that the
original extension was much greater than now seen. The