Jökull - 01.12.1969, Síða 127

Reykjahh'O
SKYRINGAR
BH Alltafautt
Venjulegast autt
Autt í mildri tíð
im Lagís
'^’**^* Sprunga
• •••••• Bílaleið
Grœnavatn
Jóh.S/S.Rist/G
Fig. 3. Cracks and tracks. Early in winter a fissure runs through the lake at 1 or 2, never on
both. Main direction of cracks and ice wrinkles is E—W, going N—S only between the islands
Svidinsey and Bekrar.
up by ice, but this did not bring about the
required aid. The Hydrological Survey of NEA
was then asked to undertake an investigation
of ice phenomena in Laxá and Mývatn. Thi|
mvestigation was carried out by the present
writer mostly during the years 1950—1953.
Now some phenomena of the behaviour of
the ice in the lake will be discussed. Eig. 2
demonstrates leads in the ice cover. At the
east shore the water is open where springs issue
from the lava; this open water is a spring lead.
The through-flow in the lake reduces the
thickness of the ice only negligible, the ice
cover usually reaches 70—80 cm in thickness
although in single years it may surpass 1 m.
The growth of the ice thickness is primarily
depending on the snow cover, a dry snow layer
reduces the freezing process.
As the water equivalent of the snow pack
in millimeters reaches the ice thickness in centi-
rneters the ice is immersed, and water bleeds
JÖKULL 19. ÁR 1 23