Jökull - 01.12.1978, Page 109

MARINE LIMITS IN DÝRAFJÖRDUR
AND ARNARFJÖRDUR, NW-ICELAND
Eggert Lárusson,
Geography Department, Durham University
In the years 1973—1977 a research team,
organized by the Geography Department of
Durham University, carried out Geomorpho-
logical and Chronological research in NW-
Iceland, Vestfirdir. An essential part of the
chronological investigations into the Late —
Glacial period was the identification and
altitude measurements of the highest marine
limits. This report summarizes the work done
by the author on the highest marine limits in
Dýrafjördur and northern Arnarfjördur.
Right above the farm at Núpur in Dýra-
fjördur there is a prominent and impressive
terrace feature with its backend at 111 ± 2 m
a.s.l. On the pass between Mýrarfell and
Gardshlídar in Dýrafjördur there is an abun-
dance of raised marine features. The highest
features, storm beaches, reach an estimated
altitude of 110 ± 10 m. Further up the fjord,
at Höfdi, thick deposits of bedded sands and
gravels were observed up to an altitude of
about 86 m, with cliffs immediately above. On
the slopes of Helgafell, at the mouth of Dýra-
fjördur, thick deposits of coarse bedded
gravels, all very well rounded, were observed
up to an altitude of about 85 m. Near Húsa-
dalur in northern Arnarfjördur there is an
impressive series of raised beaches up to an
altitude of 86 ±2 m, with rocks above.
In general it can be said that the evidence
for very high (60 m or more) marine limits in
the area has not got great chances of surviving
since the fjords are surrounded by very steep
mountains very close to the sea. However,
raised marine features, mostly terraces, can be
said to be common below an altitude of 60—
65 m.
The results reported here seriously chal-
lenge the prevailing theories on the heights of
marine limits in Iceland. Also, the history of
Late-Glacial and Post-Glacial emergence in
Iceland has to be reinterpreted.
A NOTE ON NOMENCLATURE OF
SUBMARINE RIDGES IN ICELANDIC
WATERS
Svend-Aage Malmberg,
Marine Research Institute
The oceans around Iceland are divided by
several submarine ridges which are known by
various names in the literature. In this note it
is attempted to eliminate the incongruity in
the nomenclature of these ridges. General
topographic features of the ridges are desc-
ribed.
Suggested names for the main submarine
ridges extending from Iceland are as follows:
Reykjanes Ridge to the SW, the Greenland-Iceland
Ridge to the NW, the Kolbeinsey Ridge to the
north at 18°W, the Iceland-Jan Mayen Ridge to
the NE towards Jan Mayen at 8°W, the
Iceland-Faroe Ridge to the SE, and the new
name Katla Ridges to the south at 18—19°W
(sedimentary ridges between canyons cutting
the Icelandic continental slope).
NEAR-BOTTOM DIRECT CURRENT
MEASUREMENTS ON THE ICELANDIC
SHELF — OVERFLOW 73 —
Svend-Aage Malmberg,
Marine Research Institute
Information on near-bottom currents are
important for studies on sediments and bot-
tom topography. The bottom topography, on
the other hand, affects oceanic currents.
Near-bottom direct current measurements at
200 m depth on the Icelandic shelf NW and
SE of Iceland show that bottom topography
and atmospheric pressure variations, besides
tidal variations, influence the currents, both in
direction and with a periodicity of 2—3 days
and 2—3 weeks. The current speed varies from
zero up to 0.8 knots.
JÖKULL 28. ÁR 107