Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 13

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that of the 100 m stage (Einarsson 1958 h). The work of the
Older 300 m stage is difficult to estimate. It is perhaps not
less than that of the Younger 300 m stage and the correspond-
ing time might he longer.
It seems difficult to account for all this work unless we
reckon with a time span since the Middle or Lower Pliocene.
It is perhaps not without significance in this connection that
the oldest remnants of erosion surfaces in the Eastern Alps
range back to the Upper Miocene (Winkler-Hermaden 1957);
it would not be surprising if forms on basalts could range
as far back as this.
However, we shall later come to the conclusion that a ge-
neral glaciation of the country is older than both 300 m ero-
sion stages (but younger than the peneplanation), and this
glaciation might on good grounds be considered as Pleistocene.
Thus we must face the question whether Pleistocene condi-
tions began exceptionally early in Iceland or whether such
a very high erosion rate as indicated is more acceptable.
To summarize, the strandplane stage seems, both by study
of the Pleistocene in the Eyjafjörður valley system and by
the testimony of the reversely polarized lavas in Skagafjörður,
to range back to the Lower Pleistocene. Before that time lies
the development of the two valley systems at the 300 m base
level. Although the valleys were very likely initiated by
faults and some broad ones (Skagafjörður) are largely of tec-
tonic origin, nevertheless the erosion of the basalts is immense
and demands a long time. It seems difficult to account for
all this erosion within the Pleistocene unless this was much
longer than usually assumed.
II. The Young Rocks.
To this group are referred all rocks younger than the Older
300 m stage. In addition we include a group of basalts, which
we shall call the Young Plateau Basalts, which in some areas
form the highest member of the Plateau and are older than