Greinar (Vísindafélag Íslendinga) - 01.01.1977, Page 42

40
deposits are probably not exposed, but found below the bottom
of the Skjálfandi Bay.
The Pliocene development in the North Sea is very strange
and its position and easy isolation from the main development
in the Atlantic makes this area unfit as a stratigraphic stand-
ard to be used also in Iceland, as we shall also see, although
just this has been done in the past.
The Lower Pliocene was warm in southern England, where
the warm Gulf Stream could have had direct influence. But in
East Anglia the development is strange. The “warm character
of the fauna persists, though weakening, in the Coralline Crag”
(30, p. 595), on the other hand in the overlying Red Crag . . .
“the warm species have completely disappeared and only cold
forms remain. Probably the connections with the Atlantic were
suspended” (l.c. p. 595). This seems the only correct explana-
tion, for we have no reason to expect such sudden change of
the Gulf Stream in the Lower Pliocene.
The Lower Pliocene or older North Pacific invertebrates,
such as reached Tjörnes, could not be expected to migrate
farther south during the strong Lower Pliocene or earlier
Gulf Stream. Only towards the end of the Pliocene they could
and did do so, to appear in the Norwich Crag of Villafran-
chian age.
Gignoux (30) gives just the same explanation, but without re-
ference to the Gulf Stream or the Bering Strait, “northern forms
(containing the Pacific ones) appear in the Norwich Crag
due perhaps to the chilling at the end of the Pliocene” (l.c.
p. 595).
Thus the Pacific forms which lived at Tjörnes in the Lower
Pliocene or earlier, could not reach East Anglia before the
end of the Pliocene. But East Anglia has hitherto been used
to date the Tjörnes deposits! No wonder why I have never in
my geological work since 1940 (31) been satisfied with the
low age of the Tjörnes deposits, because such an age did not
harmonize with morphology of the mountainous area west of
Bárðardalur,