Greinar (Vísindafélag Íslendinga) - 01.01.1935, Síða 90

88
ent changes in the relative positions of land and sea
as indicated above, occurred at places so close to-
gether.
The investigation made by Prof. Knud Jessen into
the plant remains shows that there was no birch grow-
ing here when the doleritic lava flowed in the neigh-
bourhood of Gelgjutangi. That need not necessarily
mean that the climate was then so cold that birch
could not grow here. The alternative explanation is
possible, that such a short time had elapsed since 'the
climate improved that the birch had not had time to
spread north here. In other respects those plants which
have been found in this stratum give no definite re-
ply to the question as to what kind of climate there
was here at that interglacial period. The type of
vegetation which is suggested by those plant species
which have been found in the stratum is now common
everywhere in Iceland, and really proves nothing save
that the climate then might have been very similar to
what it is now. Some more definite ideas of the climate
of the interglacial epoch may be gathered from the
species of insects found.
Nebria Gyllenhali, Patrobus septentrionis, and Byrr-
hus fasciatus flourish now in all parts of Iceland. Aga-
bus solieri has not as yet been found in the north-east
of the country, but is otherwise very common even high
up in the mountains. On the other hand Dr. Henriksen
points out that Pterostichus diligens and Tachinus
collaris require a milder climate. The former species has
indeed been found in the north of the country, but only
in two places and there by hot springs, but it is on the
other hand much more common in the south of the
country.1* Tachinus collaris has not been found in the
north of the country and, judging from its distribution,
would seem to demand an average temperature of + 2°
1) cf. C. H. Lindroth, Die Insektenfauna Islands, Uppsala
1931, pp. 451, 465 and 467,