Rit (Vísindafélag Íslendinga) - 01.06.1923, Page 116

112
about2 m. higher than at the present time, (4 borea! species:
Mytilus modiolus, M. edulis, Littorina rudis, L. obtusata).
d) List of tbe fossil shells found in the old marine deposits
in Borgarfjöröur and Hvalfjörður (pp. 87 —QO).
The species are divided here into two groups, arctic and
boreal species, and are arranged in order on the list ac-
cording to the height above sea-Ieve! at which they occur.
The first column after the names of the species shows the
height above sea-leve! at which they were found (m.). Co!s.
1 —VI show the distribution of the species at the various
localities, which are here grouped according to the probable
age of the shell strata where they were found (I, the oldest,
VI, the most recent). The numbers 1 — 29 correspond to
the numbers of the localities on the accompanying map
and on p. 78.
The list shows that the arctic species which bear evidence
of the coldest conditions (Sipho togatus etc.) occur in every
case on outlying points outside the fjords, at the bottom
of the terraces, only a few metres above sea-level (I —II).
The boreal species occur higher up in the terraces in Borg-
arfjörður (III; highest abt. 25 m. above sea-level), and also
in the most recent shell strata outside the fjords, where they
are more frequent in the lowlying localities. (V & VI).
8. Summctry, and comparison with fossil shell straia
in Borgarfjörður (pp. 91—97).
1. When the outlying points near the mouth of Borgar-
fjörður and Hvalfjörður became free from the ice sheet in
the late Glacial Period, the land probably stood as low or
lower than at present, in relation to the sea-level. After that
the land subsided and the sea invaded the coast, until the
coast-line reached its highest point, abt. 100 m. higher than
at present (No. 1 in Fig. 8). At the commencement of this
subsidence the sheil strata at Langasand, Heynes and Gröf