Jökull - 01.12.1981, Síða 24

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and phase is tentatively dated to between
1930 and the early 1940s.
iii) More recent retreat has not led to the
formation of clear ridge sequences which
have survived, but a position can be
defined for 1946 on the basis of aerial
photography and this lies within the
ridge series mentioned in ii).
iv) The date when Gljúfurárjökull stopped
retreating is not known exactly but was
between 1972 and 1977 when expedition
reports note a steepening of the ice front.
In 1972 the position of the ice margin was
very close to that mapped in 1979.
v) Between 1977 and 1979 the terminus of
Gljúfurárjökull advanced by between 30
and 50 m, although the advance may well
have begun one or two years before 1977.
The mean horizontal ice surface velocity
for 1977—1979 as measured at two
locations in the snout portion of the
glacier was c. 26 m/year.
ACKNOWLEDGEMENTS
In addition to the authors, the Exeter University
North Iceland Expedition 1979 included Kate Car-
michael, Jennette Edwards, Paul Kirby, Kathryn
Padgham and Sue Viner. We are grateful to Hjörtur
Thórarinsson of Tjörn for his help and hospitality,
Tony Escritt for his help during the planning of the
expedition, and the staff of the Drawing Office of the
Department of Geography, University of Exeter, for
drawing the figures.
NOTE ADDED IN PROOF:
With respect to the last sentence on p. 13, it
has come to our attention that a small
advance, 5 m, was noted for Gljúfurárjökull in
1969/70 by Vignir Sveinsson of Thverá. (See
E. A. Escritt (ed.) 1974: North Iceland Glacier
Inventory — A Manual for Field Survey
Parties. Young Explorers’ Trust, 60 pp.). No
other period of advance was recorded between
1939 and 1971/72.
REFERENCES
Caseldine, C. J. (compiler) 1981: Report of
Exeter University North Iceland Ex-
pedition 1979.
Cullingford, R. A. and Gregory, K. J., 1978: Till
ridges in Wensleydale, Yorkshire. Proc.
Geol. Ass., 89: 67-79.
Eythórsson, J. 1956: Frá Norðurlandsjöklum.
Jökull, 6: 23-28.
— 1963: Variation of Icelandic glaciers
1931-1960. Jökull, 13: 31—33.
Gregory, K. J. and Cullingford, R. A., 1974:
Lateral variations in pebble shape in
northwest Yorkshire. Sediment. Geol., 12:
237-248.
Persson, Á. 1964: The vegetation at the margin
of the retreating glacier, Skaftafellsjökull.
Bot. Notiser, 117: 323 — 354.
Rist, S. 1977: Jöklabreytingar 1964/65 —
1973-74 (10 ár), 1974/75-1975/76 (2 ár)
og 1976/77. Jökull, 27: 88-93.
Stork, A. 1963: Plant immigration in front of
retreating glaciers, with examples from
Kebnekajse area, N. Sweden. Geogr.
Annlr, 45A: 1—22.
ÁGRIP
Höfundar, tveir háskólakennarar frá
Exeter, birta hér kort af sporði Gljúfurárjökuls
og jökulurðum framan við hann, og ræða
breytingar í legu sporðsins og landnám
plantna er jökullinn hörfar. A árunum 1977 til
1979 skreið sporðurinn fram 30 til 50 m og
meðalhraði við yfirborð mældist um 26 m á
ári.
Manuscript received 6th October 1981.
22 JÖKULL 31. ÁR