Jökull - 01.12.1983, Page 96

the ice sheet of the central highland on the other
can be clearly seen. On closer examination this
difference is not only apparent in the large scale
landforms but in the smaller ones too. A well dev-
eloped roche-moutonnée landscape where erosion
by a comparatively thick glacier has been very eff-
ective is very widespread in Scandinavia and Can-
ada, but in Iceland it is only found in Fljótsdalshér-
að, in a small area in Borgarfjördur and a very few
other areas. In the very same places very well deve-
loped large glacial grooves (flutations) are also
found such as can be seen in Fig. 7 which shows
glacial grooves in the Sledbrjótur region in Hérad.
Here a sinuous groove can be seen, a socalled “cave-
tto“, a feature believed represent “highly plastic“
erosion (Gjessing 1965, 1966). Thissuggests that the
erosive capability ofglaciers has been most in these
areas, since as well known it depends mainly on the
glacier thickness and the rate of flow.
Widespread on the fjord pnomontories and
mountain sides near the coast are to be found large,
steep talus slopes, especially where characteristic
features of marine erosion are dominant, as for ex-
ample on Hvalnes (Fig. 6). Such screes are hardly
found inland where glacial erosion features are
dominant. Towards the top of the screes is a net-
work of water eroded gullies, which are often tens of
meters deep, so that the landscape there appears as
a forest of pyramids (buttresses) uppermost in the
mountain sides. (Figs.6 and 8). A number ofwater
eroded gullies can be seen in Fig. 8, which extend
side by side downslope from the corrie landscape
farthest up the mountain. The talus, gullies and
pyramids bear witness to very active water erosion
and frost weathering of long duration. The position
of these strongly water eroded areas on peninsulas
and farther out the fjords slopes decidedly suggest
that they have been subjected to little or no glacial
erosion during the last glaciation and possibly oth-
ers, since their position agrees with probable ice free
areas, as they are shown in Fig. 4.
Well developed glacial cols (Fig. 9) can be found
widespread in the alpine landscapeand they give an
idea of the thickness of the valley or fjord glaciers at
their time of formation. Helgi Pjetursson (1906) and
Trausti Einarsson (1959) have treated them in their
work and the latter has pointed out that in some
places they are found at two or more altitude levels.
A rather thicker weathering cover is widespread
above the main valley or fjord glaciation limits (Fig.
4) than below them, and all glacial erosional forms
are considerably more subdued there. One of the
Fig. 8. Northern slope of Nordfjördur from Odd-
skardsvegur. At the top are horns, serrated edges
and corries, which characterise the alpine land-
scape. Below is a greatly water eroded gully slope.
To the right is the serrated edge of Bagall and
beneath Bagall corrie. In front of them is landslide
debris and perhaps bottom moraine. It is likely
that the gully walls were ice free during the last
glaciation, but the thick till cover below them
represents the glacial maximum. Smoke from
capelin processing plant fills the valley floor.
— Photo G. Sigbj.
Mynd 8. Norðurhlíðar Norbjjarðar frá Oddsskarðsvegi.
Efst eru eggjar, tindar og botnar, sem einkenna alpalands-
lag. Neðan við er giljótt mjög vatnsrofin hlíð. Til htegri er
tindurinn Bagall og undir honum Bagalsbotnar. Framan
við þá er framhlauþsurð og e. t. v. botnjökulsruðningur.
Líklegt er að giljahlíðin hafi verið ísvana á síðasta
jökulskeiði, en þykk jökulruðningskápan neðan hennar sé
jökulhámarkið. Reykur frá loðnubrteðslu fyllir dalbotninn.
— Ljósm. G. Sigbj.
clearest examples which I have seen ofthis is where
the weathering cover thickness and glacially eroded
forms become more subdued at 200-250 m a.s.l. at
the Vatnsskard road to eastern Borgarfjördur.
THE SOUTHEASTERN COAST FROM
EYJAFJÖLL TO FLJÓTSDALSHÉR,\Ð
On Fig. 3 it can be seen that the coastal moutains
are almost everywhere formed by alpine glaciers
and marine erosion is also well developed there. A
survey of the glacially eroded landförms from Breid-
dalsvík to Eyjafjöll reveals that glacially eroded val-
leys and fjords are very poorly developed compared
with Fljótsdalshérad and mid northern Iceland in
94 JÖKULL 33. ÁR