Jökull - 01.12.1993, Page 37

Figure 2. The lateral mor-
aine, the 65 m sedimentary
terrace and the 50 m and
40 m shorelines above the
houses at the Vellir farm
at the head of the Viðar-
vík cove (photo Hreggvið-
ur Norðdahl). — Jökulgarð-
urog sethjalli í um 65 m hœð.
Fjörumörk í 50 og 40 m hœð
eru utan og ofan við bœjar-
húsin á Völlum í Viðarvík.
area were formed during "Das Langanesstadium", a
Lateglacial readvance of the glaciers which Einarsson
(1961) correlated with the Alftanes glacial readvance
in southwest Iceland. K. Sæmundsson (1977) com-
piled a geological map of the bedrock of northeast
Iceland, also showing glacial striae and raised shore-
line features. Hjartarson et al. (1981) found raised
terraces and shorelines well above present sea-level in
the Bakkaflói area.
This paper is based on fieldwork carried out by the
authors at intervals between 1986 and 1993.
methods
Variations in the altitude of relative sea-level and in
the areal extent of the glaciers in Iceland are a reaction
to contemporaneous climatic changes in the North At-
lantic Region. It has been shown that climatic changes
of a stadial amplitude, reflected in the extent of the
Icelandic glaciers and, thus, also in crustal overburden
load, lead to more or less instantaneous glacio-isostatic
response with relative sea-level changes (Norðdahl,
1983; Sigmundsson, 1991). Thisintimaterelationship
between climatic changes and changes in glacier ex-
tent and the altitude of relative sea-level are key argu-
ments when reconstructing local relative deglaciation
history (Kjartansson, 1958; Norðdahl and Einarsson,
1988).
During our field work in northeast Iceland we put
the main emphasis on studies of raised shorelines, flu-
vioglacial deposits accumulated close to contempora-
neous marine levels, moraines and other ice-marginal
features. Most of the surveyed shoreline features are
abrasional cliffs or prominent beach ridges. Some flu-
vioglacial sediment accumulations and abraded ter-
races have also been used as sea-level indicators. The
altitude of raised shoreline features was determined
with an aneroid Paulin altimeter and referred to the
sea as base-level. Corrections relating to atmospheric
pressure changes and tidal differences were performed
in accordance with the procedure described by Norð-
dahl and Einarsson (1988).
An examination of the shoreline data enables us
to fit the history of deglaciation and sea-level changes
in the Þistilfjörður and Bakkaflói areas to a multi-
advance deglaciation (MAD) model, which is based
on several detailed regional deglaciation studies in Ice-
land (Norðdahl, 1991). The MAD-model contains an
JÖKULL, No. 43, 1993 35