Jökull - 01.12.1964, Blaðsíða 8

ed from gravity measurements at the edge of
the ice cap, or from combined seismic and
gravity measurements at a few stations on the
ice. The gravity measurements are then well
suited to interpolation between seismic thick-
ness determinations.
In this work only few seismic thickness deter-
minations were available in the area surveyed.
On the profile Grímsfjall—Kverkfjöll only one
seismic station was used to estimate the crustal
Bouguer anomaly, which then was assumed to
be constant along the whole profile.
In the Grímsvötn area absolute ice-thickness
determination is uncertain due to insufficient
control in the form of reliable seismic ice-thick-
ness determinations, but variations in ice-thick-
ness can probably be considered reliable over
limited areas. In the Grímsvötn depression a
minimum estimate of ice-thickness of 110 meters
was found. A subglacial ridge, 150—200 meters
high above the bottom of the depression, was
found at the eastern edge of the Grímsvötn
depression.
Further gravity work on Vatnajökull for ice-
thickness determination should be accompanied
by an increased number of seismic. control sta-
tions. Such combined work would give, besides
ice-thickness, valuable data for the general
picture of the crustal Bouguer anomalies in the
Vatnajökull area.
ACKNOWLEDGEMENTS
The present work was made possible by the
geodetic measurements which were being car-
ried out in the Grímsvötn area by Mr. Gunnar
Thorbergsson, Mr. Steingrímur Pálsson and Mr.
Sigmundur Freysteinsson. The gravity measure-
ments along the line Grímsfjall—Kverkfjöll
were made by Mr. Örn Gardarsson. Mr. Sigur-
jón Rist yielded invaluable help in navigating
the weasel between the gravity stations. Mr.
Jón Jónsson, geologist of the State Electricity
Authority, supplied a Paulin altimeter for the
first expedition. To all these persons the author
wishes to express his gratitude.
REFEREN CES
Bull, C„ and Hardy, J. R„ 1956. The determi-
nation of the thickness of a glacier from
Frá félaginu
AÐALFUNDUR
Aðalfundur var haldinn í Breiðfirðingabúð
21. febr. 1964. Fundinn sóttu 64 manns. Fund-
arstjóri var Einar Sæmundsson.
Þetta gerðist:
1. Formaður flutti skýrslu stjórnar um störf
félagsins á liðnu starfsári.
2. Lagðir voru fram endurskoðaðir reikningar
félagsins. Eignir félagsins í árslok voru metn-
ar á kr. 299.277,72. Félagsmenn voru 312.
3. í stjórn voru endurkjörnir Arni Stefánsson,
Sigurður Þórarinsson, Sigurjón Rist og
Trausti Einarsson. Jón Evþórsson er for-
maður til aðalfundar 1966. I varastjórn voru
endurkjörnir Guðmundur Jónasson, Magnús
Jóhannsson og Stefán Bjarnason og endur-
skoðendur Páll Sigurðsson, Rögnvaldur Þor-
kelsson og Gunnar Böðvarsson.
4. I fundarlok var kaffidrykkja og síðan sýndu
Sigurður Þórarinsson og Magnús Jóhannsson
litskuggamyndir af Brúarjökli og svæðinu
kringum Pálsfjall. Sigurður ræddi einnig um
túndrutígla á hálendinu og sýndi myndir af
þeim.
ÚR SKÝRSLU FORMANNS
Formenn starfsnefnda félagsins eru:
Ferðanefnd: Magnús Jóhannsson
Skálanefnd: Stefán Bjarnason
Skemmtinefnd: Halldóra Thoroddsen
Bílanefnd: Gunnar Guðmundsson
Vísindasjóður veitti 30 þúsund krónur til þess
að halda uppi veðurathugunum í Jökulheimum.
Hófust þær 12. júní og var þeim haldið uppi
óslitið til 24. september. Lengst af sá Flelgi
Björnsson, stúdent, um veðurathuganirnar, eða
frá júnílokum fram í miðjan ágúst. Þá tók við
Pétur Sumarliðason, kennari, í hálfan mánuð
og síðan Sigurður Sverrisson.
measurements of the value of gravity. J.
Glaciology, 2: 755—762.
Einarsson, Tr„ 1954. A survey of gravity in Ice-
land. Soc. Sci. Islandica, XXX, Reykjavík.
Joset, A„ and Holtzscherer, J. J„ 1954. Expedi-
tion Franco-Islandaise au Vatnajökull,
Marz—avril 1951. Resultates des sondages
seismique. Jökull, 4: 1—32.
Thorarinsson, S„ 1965. Personal communication.
66
JOKULL 1964