Jökull - 01.12.1970, Blaðsíða 31

Fig. 2. Profile across proglacial area.
was subsequently modified by those streams
which cut through the moraine systems after
1890, and continued to function as the ice front
retreated north-westwards.
The retreat of the ice front from the 1890
moraine resulted in the development of a com-
plex drainage system and both the retreat of
the ice and the development of the drainage
system were affected by the nature of the sur-
face exposed as the ice wasted away. Within
one kilometre of the outermost moraine the
tops of moraine ridges attain altitudes between
20 and 40 m (Fig. 2). In the area west of Jökuls-
árlón the highest altitudes occur on the south-
eastern side of the moraine system and towards
the north-west the surface falls by a series of
steps (i.e. meltwater channels parallel to the
moraine ridges) down to 20 m. Altitudes then
rise steadily to 40 m before dropping to 25 m
near the ice margin. East of Jökulsárlón the
highest altitudes occur on the north-west side
of the outermost moraine system. The ridges
on the south-east side of the system attain alti-
tudes of 10—15 m whereas one ridge on the
north-west side of the system attains over 40 m.
Behind this moraine system altitudes fall to
10 m before rising steadily to between 25 and
40 m and then falling again to 10 to 30 m at
the ice front. The morphological pattern is
similar throughout the proglacial area in that
there are two zones of high ground which have
prevented the direct movement of meltwaters
to the south and south-east and at right angles
to the margin of Breidamerkurjökull. The
result is that at times drainage systems almost
parallel to the ice front have been developed.
Several hundred channels were mapped in the
field but only the most significant ones are
discussed in this paper.
THE NATURE OF THE EVIDENCE
The area of study is very well documented
for the period 1904 to 1965. The documenta-
tion, in the form of maps and aerial photo-
graphs is supported by local information pro-
vided by Mr. Flosi Björnsson of Kvísker and
by fieldwork carried out by the authors.
The following maps of the area, or parts of
it, have been consulted.
JÖKULL 20. ÁR 29