Rit (Vísindafélag Íslendinga) - 01.07.1962, Side 34

34
(total thickness 10—15 m; well rounded fluviatile gravel and
fluviatile or eolian sand). At Friðmundarvötn reverse lavas
reach a height of 447 m, and if a normal group separates
these from the lavas in the canyon, it cannot be thicker than
about 20 m. It rather appears, therefore, that the normal
group in Stóradalsháls is absent here. At Gilsá, where the old
basalts reach a level of 340 m, the lower reverse group of
Stóradalsháls is absent. Thus the individual groups, when
thin, have a different distribution, depending on the prevail-
ing topography as we found already in Hvammsgil.
3. Vatnsdalur. The Young rocks appear at the southern
end of this valley at a height of about 400 m, underlain by
the southwards dipping old basalts. One exposure of their
base is seen just below the waterfall Skínandi in Vatnsdalsá.
At 375 m we have still the old basalts with infillings. At
400 m is the first Young lava, fresh, thick, of reverse magne-
tization. This is covered by a 2 m thick conglomerate; a grey-
brown matrix with rather large cobbles. The surface of the
lava under the conglomerate has been disintegrated by frost
and has been floating in mud, a common feature connected
with the moraine-like conglomerates in the Young Plateau
Basalts. Signs of a true glaciation were not found. The conglo-
merate is very hard and fractures in it have white linings.
This conglomerate represents the interval between two mag-
netic groups, for it is covered by a lava of normal magne-
tization.
Another outcrop is found af Bríkarkvísl. At 370 m we have
old basalts with infillings. These are covered by a 4—5 m
thick grey conglomerate whose floor is not glacially striated.
The conglomerate is covered by a fresh porphyritic lava of
normal magnetization. The conglomerate contains pebbles of
old and young basalts, in harmony with its position at Skin-
andi.
4. VíSidalur. An outlier of the Young rocks extends into
this valley and an important exposure is found at Bakka-
brúnir, where a lava of normal magnetization covers fossili-