Rit (Vísindafélag Íslendinga) - 01.07.1962, Síða 155

153
scree layers are found. Most likely this is a remnant com-
parable to Suðurmúli, and lying in a sheltered position (down-
faulted) below the general surface of the surrounding basalts.
But the dip indicates that the origin of the material is in the
direction of Thverfell. This, in connection with the late ori-
gin of the latter, seems to indicate that Thverfell may he
due to renewed activity in a much older volcanic centre.
Finally, an occurrence of Young rocks near the farm Vatns-
horn in Skorradalur shall be mentioned. The dip of the Pla-
teau basalts is here about 15° SE but on these rest nearly
horizontal sediments (there is a very slight SE dip) on the
slope of the valley at a height of 230—240 m. The sediments
contain gravel at the base but consist mainly of sand and
have a thickness of about 30 m. They are cut by at least 5
nearly vertical dykes of normal magnetization and contain
a normal lava which is of much fresher look than the Plateau
basalts. At one place the sediment is overlain by a fresh re-
verse primary breccia. These sediments and volcanic rocks
I consider as having been formed during an early stage of
the valley when the base level was some 230 m above pre-
sent sea-level. They confirm our results in Northern Iceland
that volcanic activity went on during the early stages of
the valleys.
Northern part of the Ok area. In the lower part of the
gully Rauðsgil (cf. Map V) we have a reverse group which
we shall term r6.’) Fligher in the gully it is overlain by n6.
These groups dip 8° SE. Farther east come the concordant
groups r5 and n5. Following now the Valagil we have a new
reverse group, r4, and a thick normal one, n4 or the Valagil
normal group, in which we find the lowest vestiges of frost
action and of glacier work in this area; there is a case of a
J) In a map given in Einarsson (1957) this group was termed R4.
The overlying groups in the present area had not been studied in detail
at that time and the notation was based on a connection with the Hval-
fjörður area from the west. The discrepancy is probably due to compli-
cations below R3 in Iívalfjörður which were recognized later.