Greinar (Vísindafélag Íslendinga) - 01.01.1935, Qupperneq 76

74
stage is somewhat older, but probably not more than a
1000 years older, and therefore ought to have been
formed about 10—12 thousand years ago. The calculation
of time by fluviatile deposits is, as is well known, not an
accurate method of reckoning because there may be
many factors to cause modifications, and therefore it
is very important that the varve-clay in the south of Ice-
land has been examined. Ebba H. de Geercame to
the conclusion that the varve-clay which Wadell obser-
ved in the south of Iceland was 974—1147 years older
than the end of the fini-glacial period, and che varve-
clay which Jóh. Áskelsson examined in the same locali-
ties seems to be 982—1066 years older than the fini-
glacial period.1 2) These varve-clay strata were 89 metres
above sea-level and would therefore be formed during
the Akureyri-stage, or possibly somewhat before or after
that time. It ought to be permissible to infer from these
age-determinations that the Akureyri-stage is not much
older than eleven thousand years, and not younger chan
nine thousand, and that agrees well with my age-deter-
minations from the fluviatile deposits which were men-
tioned above.
The Akureyri-stage is characterized by a transgression
of the sea — in the west of Iceland, in Saurbær and
Borgarfjörður, the sea reached 80—90 metres higher,
and at Akureyri 70 metres higher than at present — and
by a practically coincident advance of the glaciers and
no doubt also an increase in the thickness of the ice-
cap. If we assume that the transgression is to be explained
by the principle of isostasy, the pressure on the land
having increased because of the increased weight of the
glaciers, then the average thickness of the ice-cap all
over the country would be about 240 metres. This figure
does not seem to be far wrong since the glacier at Akur-
1) Geografiska Annaler, Aargang X, 4. Stockholm 1928.
2) J. Áskelsson: On Two Varve Diagrams from Iceland. Geol.
Fören. i Stockholm, Förh. March—-April 1930, p. 214,