Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 55

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group was built up on a flat land that extended to the north
into the Breiðafjörður area. The present difference of over
200 m in the level of this land on the south and north side
of the peninsula can hardly have existed when rivers flowed
southwards in the Búlandshöfði-Kirkjufell area, so that later
displacement seems to have taken place. This displacement
may possibly have begun before or together with the Young
volcanic period but a part of it is probably younger, as our
description of the reverse group seems to indicate. The group
was in an advanced state of erosion when the normally pola-
rized rocks began to be formed. This represents a long ero-
sional interval and for this reason it is quite possible that
two or more magnetic periods are not registered, and that
the two groups found are not consecutive ones.
2b. The Normal group. It consists to a great extent of vol-
canic breccia and tuff of various grades; pillow lavas also
occur. Ordinary lava flows occur, however, in many parts. The
structure as a whole is markedly different from that of the
reverse group, the plateau character being entirely lacking.
We cannot trace the lavas horizontally for any great distance.
They seem to fill up local depressions, either of erosional ori-
gin or such formed by the uneven piling up of the frag-
mental masses. The topmost thin lavas in Kaldnasi have an
original north dip, and the lowest normal lavas at the north
end of Kambur have flowed in a slope towards the northeast.
These rocks now occur as erosional remnants, isolated on
crests between deep and broad erosional depressions. It is
mainly these morphologically developed normal rocks we
are here concerned with, not the youngest of all represent-
ed e.g. by undisturbed craters, situated in erosional slopes
or depressions of the older normal rocks.
The structure of Kaldnasi has been described; Höfðakúlur,
farther NW are made of similar rocks, lava flows forming
the highest hill (725 m). Also Helgrindur as a whole belong
to these rocks.
Böðvarsholtshyrna and Kambur deserve further description.