Greinar (Vísindafélag Íslendinga) - 01.01.1977, Page 20

18
shieldvolcano Þeistareykjabunga, on the west side of the great
gorge of the Jökulsá á Fjöllum, the signs of which were ob-
served by Sæmundsson (9) who, however considered this mor-
aine to be of Younger Dryas age „general glacier“. But an Older
Dryas age, or possibly an earlier Last-Glaciation age will emerge
below.
This Older Dryas glacier tongue is most likely also the ex-
planation of the half-circle formed relatively low land of Víði-
dalur, between Hólmatungur and Vesturdalur. The glacial great
river would, during the advance of the glacier tongue, flow on
its west side and erode Víðidalur, Fig. 2.
We need not repeat that the cluster of mountains and high
terrain north and northwest of Mývatn would most likely carry
a common glacier cap, during the Older Dryas, directing the
attention to that age for the rand moraines which are found
in the Hólkot Stage, Fig. 2.
Tracing the Hólsfjöll range farther north, the map and
especially the air photographs leave no doubt that in the north,
a glacier cap covered the Axarfjarðarheiði, between a height
of 500 m and 400 m, and the lower terrain as a flowing ice.
In fact, the ice caps of Axarfjarðarheiði, Þverfjall, Múlar,
Hvilftarfjall, and Afrétt joined in forming a flowing glacier
north along the eastern half of the lowland Slétta, right to the
present coast, where it eroded the relatively weak dolerite lava
surface, to leave a miniature „Finland", the land of thousand
lakes. On the northwest side of the Slétta peninsula, the Leir-
hafnarfjöll and probably even the low Hvammafjöll had ice
caps at the same time. It seems (subject to field test) that
from the latter a glacier flowed eastwards close to the present
shore. Furthermore it seems rather certain (again subject to
a field test) that an ice tongue extended from the southern
part of Leirhafnarfjöll down to Kópasker, Fig. 3, to provide
a straightforward explanation of the fact that during the Older
Dryas Stage, shells of C-14 age 13,500 years were overrun by
a glacier at the locality Röndin. Þorleifur Einarsson arranged
the dating of the shells, and naturally took the overlying mor-