Jökull - 01.12.1976, Page 8

Fig. 4.
Map of features above
the Lundur farm.
Mynd 4.
Kort af jarðmyndunum
ofan við Lund.
floating ice shelves (Ashwell, 1975). Much of the
large Lundur farm seems to be based on this
material.
Although one patch of this material occurs as
liigh as 88 m, most is found below 78 m. On
top of one of the hillocks a layer of cobbles
was found 79—82 m. While this may simply be
an extension of the deposits higher on the hill-
side, it could also be a result of later transport
and deposition of this and similar material,
later than the deposition of the deigulmór.
The arrangement of deposits in this area
suggests, therefore, that at some late stage in
glaciation, with a high sea-level, probably about
12,500 years B.P. as found from shell dates on
the lowland, (Ashwell, 1975), the ice over Lund-
arreykjadalur had thinned sufficiently to float
and deposit deigulmór on the valley floor. The
Ó JÖKULL26. ÁR
dark colour of this material shows that it ori-
ginated from the basalt bedrock to the north,
since most of the other deposits in Lundar-
reykjadalur are a light buff colour, having de-
rived from the Móberg rocks on the plateau to
the east. It seems probable that this silty
material was carried by water flow in the ice
through the gap occupied now by the Hrafna-
tjarnir lakes and then into the valley. Coarser
material was deposited earlier on the downward
flow, high up on the valley sides. Some, how-
ever, could have been deposited, especially at
the 79—82 m level, when sea-level was lowering
and the floating ice in the valley was thinning,
from a relict ice tongue in the Lundarsneid, as
a glaciofluvial deposit on top of the ‘deigulmór’.
Many such deposits have been found at this
height in the district.