Jökull - 01.12.1993, Blaðsíða 17
ORIGIN OF THE DRIFTWOOD ON THE COASTS OF
ICELAND; A DENDROCHRONOLOGICAL STUDY
Ólafur Eggertsson
Department of Quaternary Geology, University ofLund
Tornavagen 13 223 63 Lund, Sweden
ABSTRACT
In many places along the extensive coastline of
Iceland driftwood has been washed ashore over a long
period of time. Although the amount of driftwood
varies from place to place it isfound on almost every
beach along the coast. The wood originates in the
boreal forest regions of Russia/Siberia. Rivers which
drain these forested areas carry driftwood into the
Arctic Ocean, where it is caught in drifting ice and
transported by the oceanic currents.
A total of 343 samples of driftwood were col-
lectedfrom 3 areas in Iceland and analysed by wood
anatomical- and dendrochronological methods, aimed
at identifying the origin and age ofthe wood. A total
of24% ofthe Picea samples and 5% ofthe Pinus sam-
ples could be directly dated via tree-ring chronologies
from the White Sea region in western Russia. Addi-
tionally 54% of the Pinus samples could be grouped
together into a mean curve, that could be dated via
tree-ring chronology from the middle drainage area
°f the Yenisey river in Siberia. At present most of
the Pinus and Picea driftwood reaching Iceland are
l°gs that came loose during timber floating on the
Russian/Siberian rivers, whereas most of the Larix
driftwood has a "natural" origin, with their root sys-
tem preserved. Although North American driftwood
has been found in East Greenland it has not been en-
countered in Iceland, which suggests a partly dijferent
originfor the ice drifting south in the western and east-
ernparts, respectively, oftheEast Greenland Current.
Because of the relatively short buoyancy time of the
driftwood - most of its travel must have taken place
frozen in sea ice - it can be concluded that some of
the drift-ice reaching Iceland has the same origin as
the driftwood i.e. the Barents and Siberian seas. The
youngest dated sample indicates that it is possible for
arctic driftwood to reach the coasts oflceland in less
than six years.
INTRODU CTION
Iceland is situated at the boundary between Arctic
and Atlantic waters. The south coast is affected by the
warm and saline Atlantic water from the Gulf Stream
which flows along the west coast where it branches into
two parts, one that turns westward making a circular
current in the Irminger Sea, and another that turns to
the east along the north coast, mixing with a branch of
the East Icelandic Current (Figure 1).
Sharp boundaries occur between the warm and
cold water off the south east coast and these are even
sharper in the north west, between the warm Atlantic
water and the polar waters of the East Greenland Cur-
rent (Stefánsson, 1961). The Irminger Current is the
branch of the North Atlantic Drift that flows in a
clockwise direction around Iceland (Figure 1). In cold
years, the East Greenland Current can block off the
surface water of the Irminger Current at the north-
western peninsula, causing the north and east coasts to
be dominated by the cold Arctic surface water (Stef-
ánsson, 1962). When this happens, drifting sea ice is
common at the north coast. The east coast of Green-
land is affected by the East Greenland Current (Figures
1 and 2), which brings drift ice along the coast through-
out the year and may bring driftwood from the Arctic
JÖKULL, No. 43, 1993 15