Jökull - 01.11.1998, Side 28

hence exhibiting more extensive pattern of glacier
fluctuations.
CONCLUSIONS
The fluctuations of the Eiríksjökull ice cap during
the last 110 years have been determined for the first
time According to lichenometry, the Brækur and
Klofajökull outlet glaciers had a maximum LIA ad-
vance during 1880±9 and 1885±9, respectively. The
age of the maximum extension on the Stallurinn
plateau, where lichens were absent on the moraines,
was inferred by simple calculations of the ELA fluc-
tuations. Results indicate that the outermost LIA
moraines on Stallurinn are probably from the late
19th century like the Brækur outlet. The Stallurinn,
Brækur and Klofajökull glaciers retreated from their
maximum LIA stage up to the early sixties when they
began a re-advance. In contrast, the Ögmundarjökull
glacier retreated later or not until 1923±2.
The landform in front of the Klofajökull outlet
glacier is interpreted as a rock glacier of glaciogenic
origin depicted from its topography, internal stratigra-
phy and recent surface movements. The rock glacier
is probably active within 700 m distance from the ice-
debris boundary on the surface. This landform is pre-
historical and may initially date from the latter part of
the Holocene. Lichenometric evidence, indicating sta-
bilisation of the debris forming the outermost limit,
suggest that the Klofajökull landform was an active
rock glacier in the latter part of the 19th century.
The pattem of glacier fluctuations of the Eiríks-
jökull ice cap can be explained by the geographical
position of the ice cap. The Langjökull ice cap forms
a precipitation shadow east and south of the Eiríks-
jökull ice cap greatly reducing the precipitation reach-
ing the eastern and the western side of the ice cap.
The main source of precipitation is from north reflect-
ed in the configuration of the outlets of the ice cap
facing the main precipitation source.
According to area measurements of the Eiríks-
jökull ice cap, the glacier was largest, 49.4±0.5 km2
during the LIA (1880 -1884), smallest, 22±0.5 km2 in
the early sixties, and had grown to 23.8±0.5 km2 in
1987. Calculated ice thickness estimations indicate
that the maximum thickness of the ice cap is at pre-
sent approximately 220 m.
ACKN O WLEDGEMENT S
This study was a part of my M.Sc. thesis at the
Department of Geology and Geography, University of
Iceland. I am indebted to my tutors Prof. Thorleifur
Einarsson, University of Iceland and Oddur Sigurds-
son, National Energy Authority of Iceland, for all
their help and assistance during my M.Sc. study. Dr
Andrew J. Dugmore, University of Edinburgh and
anonymous reviewers are gratefully acknowledged
for their very helpful comments on the manuscript. I
would also like to thank farmer Kalmann Stefánsson,
Kalmannstunga II, and his wife, Bryndís Jónssdóttir,
for the generosity they showed me during the field-
work in 1990 and 1991. Finally, I would like to thank
geologist Jón Viðar Sigurðsson for his assistance dur-
ing the initial field work and for analysing the thin
sections of the lava shield.
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