Jökull - 01.12.1969, Qupperneq 151

Fig. 2.
Driftwood
on the shore
in northwestern
Iceland.
the sea ice cover lay considerably farther south
than at present, so it is reasonable to suppose
that land-fast ice could have formed a bridge
between Norway, Iceland, and Greenland and
that some transport of living species took place
along it. Though this bridge would have been
of ice and not of land, thus being rnore diffi-
cult to cross, it would have served a similar
purpose in this connection. When the climate
became still warmer in the northern oceans,
the land broke away frorn the sea ice cover,
but sea ice would have continued to drift
ashore, bringing with it gravel, earth and even
plants ancl animals.
Diaspores may blow out onto the ice ancl
be carried away by sea ice. Floes may become
temporarily land-fast on a vegetated shore and
receive deposits of soil containing parts of
plants and animals, then the floes may break
away, float off ágain and carry the species un-
liarmed to another coast, for instance that of
Iceland. Icefloes drift down the Russian rivers,
the tundra ice is lifted up in the floods and
carried out into the Arctic Ocean, and all this
merges with the pack-ice, thickens, reforms,
and is carried along with the current.
The ice-floe Arlis II is a clear example of
the transport of plants on ice from distant
regions of the Arctic Ocean. The island clrift-
ecl close to the coasts of Iceland, and it might
well have discharged its cargo at the head of
one of the North Icelandic fiorcls. It must have
been by a similar route tliat the barrel cast
adrift at Point Barrow in Alaska reached the
Melrakkaslétta plain in Northeast Iceland in
1905 (Thorocldsen 1933), (Fig. 1). In this way
driftwood also comes to Iceland; timber that
is carried into the sea, is borne by the current
north into the Arctic Ocean, and collects on
the sea ice-floes or at the ice edge. When this
ice drifts ashore the driftwood is brought with
it. Olcl records show that driftwood increases
at the northern shores with the arrival of sea
ice, the latest example being in 1965, when a
iarge amount came ashore on the northwest
peninsula of Iceland (Fig. 2). Such driftwood
is in itself an interesting subject for research.
It is useful to investigate its composition, de-
monstrate from what type of tree it has ori-
ginated and frorn where it has corne. From a
rough study made of driftwood reaching vari-
ous places in West and East Iceland, some of
the species of tree and their probable place
of growth have been determined with some
degree of accuracy. Thus, Pinus cembra lias
álmost certainly originated in Russia and must,
JÖKULL 19. ÁR 1 47