Jökull - 01.12.1978, Blaðsíða 26

GRAIN $IZt IN mm
Fig. 6. Grain-size cur-
ves of fluvioglacial sedi-
ments from Raudhóla-
sandur. The numbers
show sample locations.
Mynd 6. Kornastœrðar-
greiningar á jökulárseti frá
Rauðhólasandi. Tölurnar
sýna sýnistökustaði.
these ridges and Raudhólasandur are of
similar or the same age.
About 4 km to the east of Raudhólasandur
a broad and low moraine ridge can be fol-
lowed almost continuously in a northeasterly
direction to Austurdalur, and still further on
the other side of the valley where it is found as
a complex of ridges. The westernmost part of
the ridge consists of rather fine grained hard
till, but farther east it becomes richer in gravel
and stones. East of Reydarvatn big boulders
are common in the ridges. In view of the
direction of the glacial striae south of Bleik-
áluháls (Fig. 1) there is no doubt that Raud-
hólasandur and these ridges are synchronous.
from Illvidrahnjúkar along Austari-Jökulsá to
the point where the river turns to the north
(Fig. 1). It is less than 10—12 m broad and
4—5 m high. The till is very rich in stones and
boulders, and in some placés it consists almost
only of large boulders resembling a giant stone
fence (Fig. 8). The fine material has been
washed or blown away. About 200—300 m
inside the Vesturbugur moraine some
elongated heaps of coarse till run parallel to
the moraine ridge. The heaps are most likely
remnants of another end moraine.
Indistinct end moraine stumps can be seen
in the valley between Langihryggur and 111-
The Vesturbugur moraine
In Vesturbugur a small but very prominent
end moraine runs parallel to Austari-Jökulsá.
This ridge can be traced over nearly 5 km,
m a.s.l.
Fig. 7. A topographic profile
from Raudhólasandur to
Miklafell, compared to profiles
of two Vatnajökull outlet
glaciers. See the text for
further explanation. Explana-
tions: 1. Basalt. 2. Hyaloclas-
tite. 3. Fluvioglacial sedi-
ments.
Mynd 7. Snið frá Rauðhólasandi
til Miklafells ásamt langsniðum
Dyngjujökuls og Brúarjökuls sem
eru flatir og breiðir eins og hinn
hörfandi meginjökull er talinn hafa
verið á þessum slóðum. Líkur eru á
því að jökulhlauþið sem myndaði
Rauðhólasand hafi stafað af gosi í
Miklafelli. Skýringar: 1. Basalt. 2.
Móberg. 3. Jökulárset.
24 JÖKULL 28. ÁR