Skógræktarritið - 15.12.1991, Blaðsíða 26

Gradually the ice cover increases in thickness and reaches iceberg dimensions. Most
parts of the Arctic Ocean are very deep, some places deeper than 4.000 meters. Close to
the North Pole there is a ridge on the bottom of the sea, but still the depth is more than
1.000 meters. There is much space between the bottom and the lower part of the
icecover. This was illustrated by the US nuclear submariné tracks in the Arctic Ocean
1958-62 as reported by HERMAN (1989). Along the northern part of Norway, Russia and
Siberia, the water is rather shallow, mostly 40-60 meter deep. The water coming in from
the Atlantic Ocean to the Arctic Ocean has a salinity of 35%o. The salinity is 32%o in the
water coming in through the Bering Strait. The water outside the large rivers along the
Siberian coastline has a salinity of only a few %o. The salinity increases as the water cur-
rent moves away from the coast and mixes gradually with salt water.
It is the surface current which moves the drift logs and the ice cover. The surface cur-
rent moves from the Iarge Siberian rivers in an north-east direction until it meets the
main current coming in from the Bering Strait into the Arctic Ocean. The amount of fresh
water from the rivers is approximately 0.16 million cu.m per second while the inflow
through Bering Strait is approx. 0.30 mill. cu.m per second according to SVERDRUP,
IOHNSON and FLEMMING (1942).
Since the tree species of the driftwood and stray logs in lceland show similarities to
the tree species in the Siberian forests, it is reasonable to state that the logs from rivers
like Yenisei have been taken by storm and current and drifted in a north-eastern direc-
tion until they become stuck in the ice. Then they have been transported with the ice
over the Arctic Ocean and down between Spitsbergen and Greenland until they reach the
shores of Greenland, Spitsbergen, lan Mayen and Iceland.
The farmers in Iceland say that the Iogs sometimes come ashore packed in ice, so that
they have to loosen the logs from the ice before salvage is possible. At other times the
Iogs are coming in to the shores separated, but very often in groups of 5-10 logs each
time. Such log deposition does not occur on an annual cycle. Some years are „better"
than others, the lcelandic farmers explain. 1960 and 1978, for example, were said to be
good years.
In the future the amount of driftwood may be reduced. With a better operational, work-
ing and transport technique in Siberian an Russian logging operations, the amount of
driftwood may decrease.
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SKÓGRÆKTARRITIÐ 1991