Jökull - 01.12.1989, Blaðsíða 26

Fig. 2. Geological map of the Reykjavík area. 1) The Fossvogur layers. 2) End-moraine. 3) Raised beach.
4) Dated sample. 5) The Kópavogur shell-bearing layers.
Mynd2. Jarðfrœðikort af höfuðborgarsvœðinu. 1) Fossvogsset. 2) Jökulgarðar. 3) Forn strandlína. 4) Ald-
ursgreind sýni. 5) Setlög með skeljum í Kópavogi.
discontinuous and broken layer of a rather soft
marine silt. Consolidated and shell-rich marine
deposits underlie these layers. The deposits are hard
and with glacial striations and grooves, showing a
N32°W flow direction of the glacier. The overlying
till has a fair number of pebbles and boulders from
the marine deposits. It is obvious that here they had
become a solid rock before the glacier moved across
it. The samples AAR-6 to AAR-11 from Skerja-
fjörður, were taken from this exposure.
MORE SHELL-BEARING SEDIMENTS
An extension of the Fossvogur layers is found in
various places west of Öskjuhlíð and in the Melar
area, as previously mentioned. Shell-bearing layers
have been found in the sediments during
excavations at foundation sites for buildings in the
University area. A dating of a sample from the foun-
dation of the Student Union building (Félagsstofnun
stúdenta, Table I), shows a similar age as the shells
from Fossvogur (Einarsson, 1987).
Shells are found in a few places on Seltjarnarnes,
in sediments that overlie the Reykjavík olivine
tholeiite basalts (Guðmundsson, unpublished). They
are thought to be of the same age and partly younger
than the Fossvogur shells. Shell fragments are found
in tillite on the shore west of the golf course.
Another location was in a loose, silty sediment
above the beach south of the golf course, but it has
since been used as a site for dumping loose material.
A third location is in gravel and sand layers in the
foundations of buildings on Austurströnd, west of
24 JÖKULL, No. 39, 1989