Jökull - 01.12.1982, Blaðsíða 12

Fig. 8. Observations of glacial
markings in coastal areas; filled
circles: observations by G.H.
Mynd 8. Spor ejtirjokla í strandsvœh-
um íslands.
the north, a typical till with glacially reworked
boulders was observed. It is evident that the whole
of Reynisijall was covered by the last inland ice
sheet, as is the case with the entire area between
Mýrdalsjökull and the sea.
CONCLUDING REMARKS
Evidence of glaciation in the peripheral areas of
Iceland, brought together from several sources, is
summarized in Fig. 8, which makes it clear that the
whole coastland once was covered by the inland ice
sheet. Traces ofglacial activity on many high points
close to the present coast - a field where Kjartans-
son made an important contribution - demonstrate
that the ice sheet must have had a considerable
thickness and it invaded vast areas of the shelf. - A
thorough program of echo sounding and sub-bott-
om profiling of the sea floor, specially in front of the
fjord valleys, where end-moraines might be expect-
ed, is needed and represent a fascinating object for
research.
What about the possibility of ice-free mountain
areas? It is well known from the higher parts of the
Scandinavian mountains that glacial traces may be
scarse, even if the region definitely was covered by
the inland ice sheet. The main reason for this lack of
evidence is the intensity offrost and slope processes.
In other words, a total absence ofglacial traces does
not necessarily prove ice-free conditions. Worse
than that, from Scandinavia, Antarctica and other
areas we know that deeply weathered bedrock, nun-
atak and glacial cirque topography may have been
overridden by an ice cover without beingdestroyed.
One mountain has had a special place in the
discussions of nunataks. As Thoroddsen (1906, p.
334) did not fmd any traces of glaciation on the top
ofBláfjall south of Mývatn, l,222m high, while the
neighbouring Sellandafjall, 988 m, showed glacial
striae on its top, he thought he could compute the
ice thickness in the region. However, van Bemmelen
and Rutten in their book about the table mountains
of northern Iceland (1955) found that the top plat-
eau is mainly covered by postglacial lava, except for
a small area, where glacial scouring was observed.
Because of bad weather they were not able to give
the exact location of the area, but believe it was
“rather near the younger crater”, because there “is
the only region which shows an even surface on the
airphotos”. The area is shown on their map II. I
visited the top plateau of Bláfjall onjuly 12, 1972, in
the company of Sverrir Tryggvason of Reynihlíd.
The “even surface” was not glacially scoured but
covered by postglacial lava of the helluhraun type.
Much snow made a thorough investigation of the
whole plateau impossible and snowfree areas were
mostly covered by solifluction features. Thus the
question of whether or not there are any glacial
traces on Bláfjall remains open; even van Bentmel-
en and Rutten seem to have had some doubts about
it.
10 JÖKULL 32. ÁR