Jökull - 01.12.1985, Page 45

Fig. 12. Recent, (July 1984), view of
the section in the gravel quarry N of
Arnheiðarstaðir at about 50 m alti-
tude. The original pair of exposures
has now been destroyed, but this sect-
ion still shows the main characteristics
of the variably dipping sand and gra-
vel beds. - 12. mynd. Setlög í malar-
námu norðan við Arnheiðarstaði.
suggest that, in fact, the material was deposited by
water flowing in the regional direction into the chan-
nels, implying that this flow was englacial and subgla-
cial. This hypothesis is considered in more detail below.
To the N of the Hnaus spur the situation of the Hof
farm is rather similar to that at Skeggjastaðir, with some
of the cultivated land rising in an embayment N from
the lake shore into channels running over and to the E
and W of the steep Ásklif ridge. Just above newly
cultivated land in one channel there is a bank of
rounded material, but no section is visible. After follow-
ing the main channel near the crest of Ásklif the road
passes through a cutting and quarry of current-bedded
sands and gravels above the Ormarsstaðaá stream at
about 60 m, while to the N of the stream the sheepfold is
on similar material at about 50 m, at the entrance to the
circular embayment in which much of the Ormarsstaðir
farm is located, (Fig. 2).
This embayment has many of the characteristics
already described at Skeggjastaðir, being bounded on
the N by the slope up to the Fellaheiði plateau and by a
spur running from it to the lake shore. Channels run
from the embayment itself and round it, over the ridge
to the N. There are probably six parallel channels, but
the most prominent visual feature is a 500 m wide shelf
right above the W side of the homefield, rising from 105
m at the front to 135 m at the back against the main
slope. This shelf connects one of the channels running
to the W of Ásklif, at its lower end, to the end of one of
the channels into the spur, at its upper end. Where it
enters this upper channel the slope increases and at the
break of slope is a long, wide heap of rounded pebbles
and cobbles in a sandy matrix. Two narrow gullys run
from the N edge of the main homefield towards the
spur, at two different levels, and then widen out into
two long, narrow lakes, before rising again to the spur.
What appear to be eskers are found both below and
above the lakes from about 90 m up to 125 m. All this
would seem to justify the theory of water flow in
subglacial channels and the formation of eskers, in that
these features are not found near the crests of channels
but are deposited as the result of rising flow, (Shreve,
1972). Just below the point where Ormarsstaðaá
plunges over the edge of the Sigurðargerðisbjarg cliff to
cut through the channel system, on a channel floor over-
hanging the new gorge cut through it, lies another heap
of rounded stunes in a sandy matrix. It is of interest that
most of this 4 km wide system, except for the shelf
mentioned above, is only visible from a higher level.
From Ormarsstaðir northwards, Lagarfljót bends
more to the NE and the distance between the lake
shoreline and the higher ground to the W increases.
Banks of rounded material are less apparent but esker
structures may occur within the channels or below
ground level generally. Some distance to the N, in the
steep S bank of the Rangá stream at the side of the road
bridge about a kilometre from the junction with Lagar-
JÖKULL 35. ÁR 43