Jökull - 01.12.1985, Blaðsíða 23

this would indicate (1) that, at least in Haelavík, the
glacier had retreated behind the present coastline
around or before 9500 BP, and this (2) in turn would
suggest that the upper till at Haelavík may date from the
Younger Dryas. Whether the lower till is also of latest
Weichselian age or if it represents the Weichselian
maximum can not be said.
The Haelavík tephra
The blackish Haelavík tephra (Fig. 12) first appears
with a very sharp lower contact, in both lacustrine/
fluvial (section 3 at Haelavík) and eolian sediments
(section 2). In the latter case, deposited as a low dune
consisting almost entirely of tephra, its thickness is
approximately 0.5 m. In both the lacustrine/fluvial and
the terrestrial sediments it gradually disappears
upwards in the sections.
According to the reasoning in the preceding chapter
the age of the lacustrine/fluvial sediments where the
tephra appears is around 9000 yeárs or somewhat youn-
ger. The tephra is basaltic, and its chemical and chrono-
logical relationship to other tephras on Iceland and to
tephra beds deposited as deep-sea sediments (e.g. Kel-
I°gg et al. 1978, Ruddiman and Mclntyre 1981) and on
land in western Norway (Mangerud et al. 1984) will be
the scope of a special study. It is possible that the tephra
can be found elsewhere on the Vestfirdir peninsula, and
found in connection with dateable organic material it
could constitute an important marker horizon.
little ice age climate and glaci-
ation
Research history
Thórarinsson (1969) outlined the climatic oscillations
ln Iceland since the colonization in the 9th century AD.
According to him, the Little Ice Age cooling began
already in the early 13th century and culminated in the
18th and 19th centuries. He based his conclusions on a
multidisciplinary study involving geological,
archaeological and historical evidence. Studies of the
0/180 ratios in ice-cores from the Greenland ice sheet
have yielded similar results (Dansgaard et al. 1975).
Meteorological evidence.
Regular meteorological observations in Iceland
began in 1845, when an observation post was estab-
hshed at Stykkishólmur (Fig. 1). Eythórsson (1949),
summing up the observations, noted that the mean
annual temperature there reached its minimum between
1859 and 1888, with +2.7°C (mean values for the
periods 1901 — 1930 and 1931-1960 were +3.4°C and
4.2°C (Eythórsson 1949, M.Á. Einarsson 1976)). Thor-
oddsen (1911) published annual mean temperatures for
Stykkishólmur, and Adalvík on Hornstrandir, for
1874—1901. The mean for Stykkishólmur was then +
3.0°C (M28) and for Adalvík +1.4°C (M2). According to
M.Á. Einarsson (1976) the mean annual temperature at
Hornbjargsviti during the period 1931 — 1960 was 1.1°C
lower than at Stykkishólmur. He noted that fluctuation
trends of temperature at Stykkishólmur have been
detectable all over Iceland. Thus it seems (1) that the
annual mean temperature on Hornstrandir is 1.0—1.5°C
lower than at Stykkishólmur, (2) that temperature
fluctuations on Hornstrandir probably are roughly in
phase with the rest of Iceland, so that (3) the Little Ice
Age temperature minimum on Hornstrandir (at least
for the period after 1845) should have been reached
sometime between 1860 and 1890. However, it is not
certain that the temperature minimum exactly coincided
with the Little Ice Age maximum glaciation, as pre-
cipitation fluctuations have to be taken into considera-
tion too. We have no precipitation values from Horn-
strandir covering this period.
Glaciological evidence.
On northern Vestfirdir there are two types of glaciers
which can provide information on the Little Ice Age
climate and glacier oscillations; (1) the Drangajökull ice
cap and its outlet glaciers, and (2) the small cirque
glaciers.
(1) Drangajökull: The outlet glaciers from Dranga-
jökull (Fig. 1) have been monitored since 1931, and
found to be sensitive to small scale climatic variations
(Eythórsson 1935, 1949, Thórarinsson 1943, Bout et al.
1955, John 1977b, Rist 1983). Eythórsson (1935) came
to the conclusion that these outlet glaciers reached their
maximum extent in historical time, probably even in
post-Weichselian time, during two separate readvanced
culminating around 1756 and 1840. According to John
(1975, 1977b) the Reykjafjördur outlet glacier on the
north side of Drangajökull reached its most advanced
position around 1850 rather than around 1756. He
recognized three moraines from the Little Ice Age,
which he „dated“ to 1840-1850, 1860-1870 and 1914-
1920.
(2) Cirques: Little is known about glacier growth in
the cirques on Hornstrandir during the Little Ice Age.
Thoroddsen (1906, 1911) reported that in 1886 and 1887
large snow fields and old firns were common close to sea
level in Adalvík and Fljótavík, although he could not
JÖKULL 35. ÁR 21