Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 70

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Considering the double glaciation of the slopes of Hvalfell
on one hand, and the normal polarization on the other it is
most likely that Hvalfell was formed in the Mindel-Riss inter-
glacial, not later. On this basis the steep-sided river channel
in the old valley would have formed before Mindel. This is
in harmony with the results in Eyjafjörður (Einarsson 1959b)
that the corresponding channel must be of rather early Pleisto-
cene age.
Súlur, Gagnheiði, Ármannsfell.
The uppermost magnetic group of the Plateau Basalts at
the head of Hvalf jörður is of normal polarity and was term-
ed N2 in the publications of Einarsson and Sigurgeirsson
(1956, 1957). On this group rest reverse lavas on Kjölur and
at the hase of Kvígindisfell, termed R,. N2 is the last but one
normal group in a local sense. But as the group belongs to
the dipping plateau and is older than planation and valley
erosion in the plateau there is no doubt that in a universal
sense it is a much earlier magnetic group. It is one of the
aims of the present study to fill up the gap between this
youngest plateau group and the upper Pleistocene normal
group.
The Súlur massif is a heap of tuff-breccias of normal pola-
rization which rests directly on the plateau group N2. The
contact is at 550 m in the west, falling to 450 m in the east.
On the west and north sides this contact runs along the
steep mountain slope and it seems difficult to escape the
conclusion that the Súlur rocks are older than this slope,
i.e. older than the topography at the head of Hvalfjörður.
But in this topography are represented the same erosional
stages as we have recognized in the Plateau Basalt area of
Middle Northern Iceland. The Súlur seem thus to be older
than at least valley erosion, and hence much older than Hval-
fell. This is also borne out by the advanced dissection of
Súlur, This massif is cut by deep and broad valleys and an