Rit (Vísindafélag Íslendinga) - 01.06.1923, Page 113

109
upper surface of terraces in which the shells were found
(m. above sea-level); Col. 4, number of species; Col. 5,
Arctic species, number (%); Col. 6, boreal species, number
(%); Col. 7, order of marine strata in which shells were
found, from the bottom upwards (leir—clay; möl = gravel).
Fossil shells are found in 29 places in the districts investi-
gated (Borgarfjörður, Hvalfjörður); 30 species of sea-shells
were found there in all; 23 arctic and 7 boreal. Besides
molluscs, several species of Balanus were found in most of
the places, and a crab species (Hyas) in one place.
All the mollusc species still live around the coasts of
lceland, with one exception (Sipho togatus) and a variety
of another species (Astarte Banksii, var. Warhami). The
high-arctic Portlandia species (Portlandia arctica etc.) was
nowhere found in these strata.
b) Shell-bearing strata in Borgarfjörður (pp. 80 — 84).
Old fossil i ferous deposits are now known to be there
in 17 places. One of them (Brúarreykir) lies about 30 m.
above sea-level (only Balanus species) but most of the
other shell-bearing strata are 10 — 25 m. above sea-level, in
terraces that extend 20 — 30 m. above sea-level.
The order of strata in these terraces is generally as
follows:
1) (Highest). Sand and surf-worn gravel, often 4 — 10 m.
thick, indistinctly stratified.
2) Laminated clay, sometimes up to 10 m. thick.')
3) Gravel and sand mixed with clay. These strata are
seen only in a few places. Occasionally they were found
resting on rocks scratched by glaciers (Neðranes).
In the lowest stratum (3) arctic species were found ex-
clusively, similar to those which now live on the North
and East Coasts of Iceland (Astarte Banksii, var. stratú).
*) In some places the clay strata were separated by a stratum of gra-
vel and sand (Grjóteyri). In Ihe upper stratum boreal species were
found (Anomia squamula), but in the lower stratum only arctic spe-
cies (Fig. 1).