Jökull - 01.12.1978, Blaðsíða 99

versity of Iceland from 1945 until his recent
retirement.
In spite of often poor facilities and working
conditions he has been vigorously active since
1934 and written a large number of articles
and books. His ideas are more often than not
controversial and he continues to present ideas
that do not follow the popular pathways.
Some of his work is now commonly accepted
as fundamental in Icelandic geology.
Trausti Einarsson has always pursued work
on his manifold interests with exceptional
dedication and hard work. He has been one of
the most active members of the Geoscience
Society of Iceland from the beginning and was
the second chairman.
SOME NOTES ON A
PLIOCENE/PLEISTOCENE-TIME
SCALE FOR ICELAND
Kristinn J. Albertsson,
Science Institute, University of Iceland
K/Ar age determinations have been carried
out on some Pliocene/Pleistocene rocks from
Iceland. The strata sequence on the Tjörnes
peninsula is of great interest as regards the
onset of Pleistocene glaciations.
A slight modification of the geomagnetic
time scale has been used with the K/Ar age
results for correlation purposes with other
areas in Iceland comprising rocks of similar
ages that also have been dated and an attempt
has been made to construct an overall corre-
lation diagram of Pliocene/Pleistocene rocks.
The conclusions are in agreement with ear-
lier work that glaciations started in Pliocene
times and a sharp climatic deterioration took
place in the North Atlantic some 3 Ma ago.
These glaciations were at first, however, most
probably inland and/or local phenomena and
the first major regional glaciation started
about 2 Ma ago, or near the end of the
Pliocene.
A FACIES CONCEPT FOR
GEOTHERMAL WATERS
Stefán Arnórsson,
National Energy Authority
The “major” element composition (Si02,
Na, K, Ca, Mg, H + , C02 (total), S04, H2S
(total), Cl, F, H2 and CH4) of deep geother-
mal waters is controlled by two independent
variables only, temperature and the supply to
the water of the incompatible element Cl. All
the other dissolved components are controlled
by mineral/solute and solute/solute chemical
equilibria. These equilibria are upset where
the water cools in upflow zones. These results
suggest that it may be useful to define
geothermal water compositions in terms of a
facies concept comparable with that of
metamorphic rocks. An important fact of a
facies concept is that all dissolved uncharged
species can theoretically be used as quan-
titative geothermometers.
LAND ELEVATION CHANGES IN THE
KRAFLA AREA 1975—1977
Axel Björnsson,
National Energy Authority, Iceland
At the beginning of the volcano-tectonic
episode in the Krafla area in December 1975 a
considerable land subsidence occurred within
and around the Krafla caldera accompanied
by a volcanic eruption and movements on
faults. Since then there have been pulsations
in land elevation changes characterized by
continuous land inflation for several weeks
interrupted by sudden deflation events lasting
1—2 days. The maximum velocity of land in-
flation is around 8 mm/day near Leirhnjúkur
in the center of the caldera but decreasing
JÖKULL 28. ÁR 97