Jökull - 01.12.1988, Blaðsíða 35

GLJÚFURÁRJÖKULL
EXETER UNIVERSITY
NORTH ICELAND EXPEDITION
1986
v Exeter University Stations
v Sawtry Village College
+
Markers
Leeds University Markers
All heights are expressed in metres
and were surveyed in 1979 (off the ice)
1981, 1983 and 1 986 (on the ice)
lce Margin 1 986
------Ice Margin 1983
------Moraine Ridges
------River
Dead lce
All contours are taken from the B.S.E.S.
1977 map and have been modified using
1979, 1981, 1983 and 1986 surveyed heights
The outer grid is also derived
from the 1977 map
N.B. Station heights on the ice are not
ice surface heights but refer to the station
bench marks
lce contours are based on ice surface heights
IV
V
100
Survey Party:
Dr C.J. Caseldine, E. Bracey, N. Caukwell,
H. Stewart, H. Wharam.
Fig. 1. Map of the snout of Gljúfurárjökull, 1986.
Mynd 1. Kort af Gljúfurárjökli, 1986.
Summer temperature above 8 °C has been con-
sidered to indicate a negative mass balance for
Gljúfurárjökull (Caseldine, 1985b).
Only one station established on the ice by earlier
groups could be located in 1986, EuIV (Fig.l), a sin-
gle large boulder embedded in the ice lying in the
center of the snout area. Measurement of the rate of
movement of the station showed an average ice
velocity at the surface of 23.2 ma_1 between 1983
and 1986, compared with 26.3 ma_1 between 1979
and 1981. The difference in rate is well outside any
potential measurement errors and suggests a genuine
reduction in surface ice velocity, possibly also
slightly masked by the necessary averaging between
JÖKULL, No. 38, 1988 33