Jökull - 01.12.1985, Page 48

Fig. 17. a) Large elongated hill in a
group near the junction Laxá with Hól-
maá above Fossvellir in Jökulsárhlíð.
These hills are up to 12 m high
and are composed apparently of ro-
unded material. Although no sections
are visible, they are probably eskers.
The base of the hills is at about 200 m
altitude. b) Isolated angular rocks
perched on the rounded stone surface
of the hills, probably representing
ablation till. — 17. mynd. Ásar nálægt
ármótum Laxár og Hólmsár ofan við
Fossvelli í Jökulsárhlíð.
with the northward movement of subglacial water. Most
of the sections examined have a covering of relatively
unsorted material which may be the result of slope
wash, periglacial or postglacial weathering, or the
deposition of ablation till derived from esker material
by a wasting mass of ice.
An area of low topography to the W of the Grímsár-
virkjun power plant and lake illustrates this point. No
good sections are available and a sample of material
from near the surface in a stream gully gave an analysis
very similar to those found in unsorted material above
the layered sections. This area is shown by Hjartarson et
al. (1981, p. 76), as a system of terminal moraines, but
the features examined on the ground on and around the
Sauðhagi farm, and in the lower part of the Stórasand-
fell farm, within the same area, are low hills with
layered sand and rounded stones and are probably
eskers. Apart from the marginal material found at
Skriðuklaustur and classified above as partly re-depo-
sited till, the only large extent of unsorted material was
that found along the valley of the upper Rangá, just N
of Sandvatn stóra, where the stream flows between 12 m
high banks of definitely morainic material, giving an
analysis typical of till, which plugged this shallow
depression at 500 m altitude.
As Hjartarson et al. (1981) suggest, the terminal
moraines of the main glaciations may lie far off the
shores of N Iceland. However, even glaciers in retreat
46 JÖKULL 35. ÁR