Jökull - 01.11.1998, Side 19

Holocene glacier fluctuations of the Eiríksjökull ice cap, west
central Iceland
Hjalti J. Guðmundsson
Department of Geology and Geography, University of Iceland
Suðurgata, 101 Reykjavík, Iceland
E-mail: hjg@mmedia.is
Abstract - Holocene fluctuations offour outlet glaciers ofthe Eiríksjökull ice cap, namely Stall-
urinn, Brœkur, Ögmundarjökull and Klofajökull west central Iceland show an interesting spatial
and temporal pattern. No evidence of recent glacier erosion was foitnd in front of the most ad-
vanced stages ofBrœkur and Ögmundarjökull, which according to lichenometry, arefrom around
1880 AD and 1923 AD, respectively. The outermost limit ofStallurinn, where lichens were absent,
is inferred to datefrom around 1880 AD. This indicates a lack ofextensive glaciation infront of
these glaciers prior to the Little lce Age (LIA) or that the earlier advances ofthe glaciers did not
exceed the LIA limit. The Klofajökull outlet exhibits a dijferent pattern offluctuation and sedi-
mentation. This outlet glacier hasformed a bulk depositional feature in its proglacier area. The
oldest part of the landform can be considered older than the Settlement oflceland (ca. 900 AD)
depicted from geomorphic evidence. This landform is identified as a rock glacier deposition.
Lichenometric evidence suggests that the Klofajökull outlet re-advanced during the late 19th cen-
tury. Simple calculations of Equilibrium Line Altitude (ELA) fluctuations suggest that during the
LIA maximum the temperature was 1.5°C lower compared with present. lce thickness calcula-
tions indicate that the maximum thickness ofthe ice cap is at present approximately 220 m.
INTRODU CTION
Glacier fluctuations in Iceland have a global sig-
nificance because of the island's location adjacent to
the boundaries of the warm North Atlantic Drift and
the cold Polar Front. Major difference in the position
°f the Polar Front are known to have characterised the
Greenland/Iceland/Norwegian Sea throughout the
Holocene (Kroc, et al., 1993). Since there is a strong
relationship between the Polar Front latitudinal posi-
tion, climatic change and variation in mass balance of
glaciers, the knowledge of the pattern and timing of
glacier fluctuations in Iceland would greatly improve
the understanding of climatic change.
This paper describes the recent glacier fluctua-
tions of the Eiríksjökull ice cap through a study of
glacier geomorphology. Four geographically diverse
outlets were studied: Stallurinn, Brækur, Klofajökull
and Ögmundarjökull (Figure 1). All of these outlets
have a series of m.oraines and other glacial landforms
in their proglacier areas representing a record of
glacier fluctuations. Studies of glacier fluctuations of
ice caps in wetter and warmer locations near the coast
have revealed an interesting pattern of glacier fluctua-
tions over the latter part of the Holocene (cf. Dug-
more, 1989). The location of the Eiríksjökull ice cap
in the west central highlands of Iceland, characterised
by a dryer and colder climate, gives an ample oppor-
tunity to study the contrasts, if any, between ice caps
in two climatically distinct areas of Iceland.
JÖKULL, No. 46, 1998
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