Jökull - 01.12.1978, Page 6

Fig. 2. Lateral channels on
Skálar. The channels incline to-
wards Ábæjardalur.
Mynd 2. Jaöarrásir á Skálum.
Rásunum hallar inn í Ábœjardal.
Djúpidalur
A mounded ablation moraine runs across
the entrance of the Djúpidalur valley in a lee
position to the main glacier in Skagafjördur
(Fig. 5). A little further west drumlins run
paralled to the main valley. The ablation
moraine is most probabiy a medial morainic
deposit. Some 2 km north of the entrance of
Djúpidalur another ablation till deposit is
located at a little lower altitude. It is assumed to
be a remnant of a lateral moraine, supposedly
a continuation of the medial moraine at the
mouth of Djúpidalur.
Hlídarfjall
Hlídarfjall (Fig. 6) is a mountain plateau at
about 500—600 m altitude situated to the
north of the mountain Ellidi (793 m) between
the Austurdalur and Vesturdalur valleys.
Along the eastern edge of this plateau deposits
of esker ridges and mounds of ablation till
cover the upper slopes down to Austurdalur
and extend in the ice direction from Ellidi.
The characteristics and the location of this
deposit indicate medial morainic origin. A
medial moraine was formed when Ellidi was
emerging as a nunatak between the valley
glaciers of Vesturdalur and Austurdalur.
Downstream from Ellidi the junction of the
two valley glaciers was lying on the east side of
the water divide on Hlídarfjall because of the
greater strength of the Vesturdalur valley
glacier.
The surface forms of this deposit grade from
rather sharp crested esker ridges to irregular
mounds, but on the surface only ablation till is
to be seen. In one of the sharpest ridges,
fluvioglacial gravel was found under a 0.6 m
thick layer of ablation till and 0.3 m of
stratified sand and silt. In the northfacing
side of Ellidi, a lateral terrace forms the
highest lying part of this deposit. The crest of
this terrace is at 580—600 m altitude and falls
25 m/km northwards.
To the north of the medial moraine,
subglacial chutes were cut into bedrock on the
Austurdalur side of Hlídarfjall (Fig. 6 and Fig.
7). The biggest of these channels run obliquely
down the hillside and the upper end is carved
into the slope which proves its subglacial
origin. The upper end is bowl-shaped which
may indicate that englacial meltwater was
running down to the base of the glacier. The
direction of this channel is guided by bedrock
fractures and the ice conditions at the time of
formation.
If the three areas of medial morainic
deposits are compared, the most conspicuous
difference has to do with the material type and
the surface forms. In the Vatnsskard-Sæ-
mundarhlíd area most of the deposits are
eskers of fluvioglacial material and only minor
4 JÖKULL 28. ÁR