Jökull - 01.12.1984, Blaðsíða 119

A Review of Late Weichselian Studies in the lower
Part of the Borgarfjörður Region, western Iceland
ÓLAFUR INGÓLFSSON
University of Lund, Department of Quaternary Geology,
Sölvegatan 13, S-223 62 Lund, Sweden
ABSTRACT
The lowlands of the Borgarfjörður region are
blanketed by fossiliferous sediments of a Late
Weichselian age, which have caught the attention
of geologists for the past 200 years. An increasing
amount of stratigraphical, palaeontological, mor-
phological and sedimentological data have been
gathered in the region. The present paper surveys
the geological literature concerning the lower part
of the region. The results of the most important
contributors are summed up, and other evidence
of value for the understanding of the Late
Weichselian environments and climate of the
region is accounted for. The literature survey
shows that many problems remain unsolved, and
that interpretations of the available data are con-
troversial. It is concluded that much of the data
need to be reexamined in order to construct a
concise picture of the Late Weichselian glacial
stratigraphy and chronology of the Borgarfjörður
region. This paper outlines the most important
aspects of such a revision and brackets the poten-
tial significance offuture research.
INTRODUCTION
Borgarfjörður is the common name for a shal-
low and broad fjord opening from the northeast
into the Faxaflói bay, and the adjacent region
situated in the southern part of central West
Iceland (Fig. 1). The main topographical features
of the region consist of a coastal plain (Hjulström
1954), flanked to the east by a steep sided plateau
of Tertiary basalts (Kjartansson 1968). Series of
valleys of varying length are cut into the plateau.
Another conspicuous topographic feature is the
Hafnarfjall-Skardsheidi volcanic massif (1055 m)
of Late Pliocene age (Fridleifsson et al. 1977).
Both the Skardsheiði massif and Mount Akrafjall
are remnants of a Late Pliocene basaltic plateau
(Fridleifsson et al. 1977). The variety of acid and
basic volcanic rocks in the bedrock of the region
(Kjartansson 1960, 1968, Sœmundsson and
Einarsson 1980) is reflected in the sediments of
the region (Ashwell 1975).
Due to the geographical location of the Bor-
garfjördur region, it has been frequented by
geologists since the beginning of geological
research in Iceland in the mid 18th century. It has
been recognized for a long time that the sedi-
ments blanketing the Borgarfjördur lowlands are
of Late Pleistocene age (Keilhack 1884, Thorodd-
sen 1892). Subfossil marine molluscs have been
discovered widely in the sediments (Ólafsson
1772, Bárdarson 1923). Because of the rapid
coastal erosion and down-cutting by the rivers,
the sediments are well exposed in many sections
in the area (Bárdarson 1923, Ashwell 1967, 1975,
Ingólfsson 1981) and thus accessible for lithostra-
tigraphical mapping. There are ample features in
the region that indicate ancient sea levels higher
than the present sea level in the region (Bárdar-
son 1923), and Thorarinsson (1958) suggested it
as an excellent spot for detailed investigations on
sea level changes in Iceland.
The present paper is a review of the literature
concerning the Late Weichselian in the area
between Andakíll-Skorradalur in the north and
Hvalfjördur in the south (Fig. 1). The review is a
part of a larger project on Late Weichselian
glacial stratigraphy and chronology of the region,
being worked on at the Department of Quater-
nary Geology, University of Lund. It is paralleled
by two other similar projects at the University of
Lund, carried out on the central north and
extreme northwest coasts of Iceland. The aim of
the literature survey is to evaluate the present
state of knowledge of the glacial geology of the
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