Jökull - 01.12.1985, Page 44

gravel cutting below Melar, some 3 km N of Bessa-
staðaá, at an altitude of about 35 km. The best exposure
is on the W side of the cutting with current-bedded
sands and pebbles, (No. 80/1 in Fig. 6), covered by a
layer of variable thickness which is much less well-
sorted, No. 80/2 in Fig. 6. The base of the bedded
deposit is obscured by debris, but the visible thickness is
about 2.5 m, while that of the unsorted deposit above is
usually about 0.5 m but some large stones, up to a third
of a metre across, occur in this material. Similar
deposits are suggested at many places along the W shore
of Lagarfljót by banks of rounded stones near Brekka,
Brekkugerði, FIús and Geitagerði, all at about 35 m,
and just N of the Arnheiðarstaðir homefields, where a
long bank of rounded material is visible at about 50 m.
There are, however, no good exposed sections in this
general area.
A little further to the N of Arnheiðarstaðir, however,
a better section is visible in another road gravel quarry,
just above the positions of Stekkhús and Parthús on the
1:100 000 Icelandic map, at about 50 m altitude. In both
the exposed faces layered and sometimes cross-bedded
sands are covered by about a metre of unsorted mate-
rial, (Fig. 12). The exposures are about 4 m deep in
each case, with the lower parts obscured by debris. As
in many of the exposures of this material the top nearby
is cultivated as hayfield. From about this point north-
wards the slope bordering the Fellaheiði plateau, which
has so far risen close to the W shore of the lake, begins
to swing away to the W along the flank of the Lagarfljót
flexure zone, and channels begin to show on it.
As mentioned previously the houses and cultivated
ground of the next pair of farms to the N, Droplaugar-
staðir and Hrafnsgerði are on two platforms at 50m and
70 m, the latter probably the strandline referred to in
Hjartarson et al. (1981, p.80). A very prominent bank of
rounded material lies just above the houses, between
the Hrafnsgerðisá stream and the foot of the Hrafns-
gerðisbjarg cliff to the W, then up into a channel
between Hrafnsgerðisbjarg and the slope up to the
plateau above. Similar material is visible in a roadcut
just to the N of Hrafnsgerði but no good exposures are
visible. Hovever, a good exposure of current-bedded
sands, again covered by about a metre of unsorted
material, occurs in a road gravel quarry just below the
farm of Teigaból a little further to the N.
This material appears to continue N without interrup-
tion to the group of farms at Skeggjastaðir and most of
the cultivated ground between 60 and 80 m lies on it.
These farms lie in an embayment between the Hnaus
spur to the E and the Fellaheiði plateau slope to the W
and, as mentioned previously, channels lead N over the
Hnaus spur, (Fig. 2). This leads directly to the question
of the origin of the material at Skeggjastaðir. If it is the
result of sub-aerial delta formation from the short
streams flowing from the channels, then this flow was in
a precisely opposite direction to that of the main water
and ice movement in the district. It seems reasonable to
Fig. 11. Bedded sands and coarse
gravels at about 70 m altitude
above and to the N of Skriðu-
klaustur. The varying angle of dip
could suggest origin in an esker.
The grassy slope above covers the
bank of coarse, relatively unsort-
ed material running from the base
of the Tröllkonustígur, left, to
Bessastadaá, rt. of the picture.
The contact between the two mat-
erials is not visible. - 11. mynd.
Setlög í um 70 m hœð yfir og
norðan við Skriðuklaustur.
42 JÖKULL 35. ÁR