Rit (Vísindafélag Íslendinga) - 01.07.1962, Blaðsíða 168

166
Fljótshverfi are cut into a 600—700 m and even higher ter-
rain but they are hardly comparable with the valleys of
Middle Northern Iceland. Possibly, therefore, they are the
work of only a part of the time which went to form the north-
ern valleys.
In Skaftártunga we have an extensive plain, somewhat
eroded, between heights of 200 and 300 m, and many hills
just reach the 300 m level, while only a few isolated points
go a little above this level. This is therefore probahly also a
remnant of a terrace from the 300 m stage.
The rocks of Síða and Fljótshverfi mostly belong to a re-
verse group, whose thickness east of Krossá is over 250 m.
Only at the base here, and at the Stjórn waterfall one finds
an underlying normal group. On the other hand one finds
a normal group of brecoia in Skaftártunga and this is also
in other ways a different rock. There is possibly a dislocation
between Skaftártunga and Skálarheiði, along the Skaftá. If
this is so the constancy of the erosion level is in itself signi-
ficant.
Mýrdalur. Here is a 10 km broad, relatively low area in
front of the much higher mountains which form the socle of
the Mýrdalsjökull. Most of this area is remarkahly well ad-
justed to a level of about 300 m, only a few isolated parts
rising above that level. In the east we have a flat terrain,
about 2 km broad and 8-—9 km long, including Höfðabrekku-
heiði and Kerlingardalsheiði, with low hills reaching between
250 and 300 m (294, 252, 289, 263, 234 m).
On the west border the terrace meets a steep slope where
the terrain rises to 488 m, whereupon this is cut by a much
younger form: the deep valley Kerlingardalur.
Seen from the east most of the terrace is quite flat and lies
at the 250—260 m level. Háafell (294 m) near Höfðabrekka
rises clearly above the terrace.
Arnarstakksheiði (3X4 km2) is quite similar; its low hills
rise to heights of 285, 293, 294 m etc. At tbe west side the ter-