Rit (Vísindafélag Íslendinga) - 01.07.1962, Blaðsíða 142

140
here about 10° NW. At the base we have a reverse group
covered by normal lavas that correspond to n in MiSfell,
i.e. n3. This is in tum covered by a thick reverse primary
breccia corresponding to U in Miðfell, i.e. r2. n3 contains a
bed of moraine-like conglomerate and another separates n3
and r2. After much erosion of the reverse hreccia this was
coveerd by a thick brown primary tuff which has been cut
by a number of dykes, hoth of the usual SW—NE trend as
of the SE-NW one. This tuff much resemhles r^ in the north-
ern part of Vörðufell.
Towards the west, in Hreppar, the reverse rocks take on west
to northwest dip and disappear west of the line Högnastaða-
ásar-Langholtsfjall. They dive under n2 in Kotlaugarfjall and
probably already in Jötufjall. In the area north of Kotlaugar-
fjall, and thus in the surroundings of Gullfoss, n2 dominates.
The contact of n2 and r2 is seen in Kotlaugarfjall, ahove the
ruin Kotlaugar, cf. Fig. 73.
The group n2 consists of columnar lavas, kubbaberg lavas,
and primary breccias. Sections are especially found in the
canyon of Hvítá. On the west side of the waterfall Gullfoss
we have the partial section shown in Fig. 74.
The group n2, which in the following we shall call the Gull-
foss group, extends with a very slight dip (ahout 2°) north
and northwest of Gullfoss. There are no good sections hut the
basalts crop out in numerous low hills. As we come close to
Bláfell in the north, and the line Sandfell-Jarlhettur in the
west, we are left in uncertainty whether the outcrops belong
to n2 or perhaps much younger rocks.
Tuming SW from Gullfoss there are many more or less
connected outcrops of the group in a zone extending to Ing-
ólfsfjall, with slight west to northwest dips: Gýgjarhólsfjall,
Fellsfjall, Beykholt—Torfastaðir, Spóastaðir-Laugarás, west
side of Hestvatn, Öndverðarnes (cf. Map II). This zonal oc-
currence of the group fits very well with that of the suggest-
ed occurrence of r2—r3 on its east side.