Jökull - 01.12.1958, Blaðsíða 11

SUMMARY:
THE GRÍMSVÖTN EXPEDITIONS
IN JUNE AND SEPTEMBER 1958
by
SIGURDUR THORARINSSON
In 1958 the Iceland Glaciological Society ar-
ranged two expeditions to Vatnajökull mainly
in order to study changes in the Grímsvötn
Area. Leaders of these expeditions were Sig-
urdur Thorarinsson and Gudmundur Jónasson.
The first expedition left Reykjavik on June 6
ancl returned on June 17■ Twenty persons went
to Grímsvötn in one Bombardier and two
Wiesels. Drivers were Gudmundur Jónasson,
Haukur Haflidason and Ólafur Nielsen. Baldur
Jóhannesson took part in the expedition as
geodecist. Assistants in the research work were
Magnús Jóhannsson and Valur Jóhannsson and
Ihose who travelled as tourists were — as in
previous expeclitions — always ready to lend a
helping hand.
A pit was dug on Tungnaárjökull in about
1100 m height near the firn line. Accumulation
autumn 1957 — June 9, 1958 was 212 cm, wat.er
value 1100 mm. Another pit was dug on June
10 on nearly the same place as previous year,
short NE of E Svíahnúkur, in about 1520 m
height. Accumulation since autumn 1957 was
156 cm, water value 2275 mm.
B. Jóhannesson carried out triangulations in
the Grimsvötn area and levelled a W-E profile
over the Grimsvötn depression from Depill to
Gridarhorn. Besides the triangulations, the
height of many points was determined with
aeroplane altimeters (Koelsman Sensitive Alti-
meters). The raising of the water level at Vatns-
hamar since Sept. 15, 1957 was exactly measured
and found to be 7.8 m in 237 days or on aver-
age 3.3 cm per day. The water level at Grídar-
horn was the same as at Vatnshamar.
Short west of E Svíahnúkur some ice caverns
besides those discovered previous autumn tuere
now found and measured. The longest one was
200 m.
Having enjoyed excellent weather in Gríms- '
vötn for three days the expedition headed for
Örœfajökull. Because of bad weather Hvanna-
dalshnúkur was not climbed.
At Jökulheimar a store-house for wiesels and
fuel was erected by tlie glacier party and a
group of members of the Glaciological Society,
led by Jón Eythórsson, who visited Jökulheimar
in connection with the expedition.
The expedition in autumn left Reykjavík on
Sept. 6 and returned on Sept. 15. Members
were 10, using only the Bombardier for the
glacier travel. Driver was Gudmundur Jónas-
son, assistants were Magnús Jóhannsson, Jó-
hannes Briem and Valur Jóhannsson. The
glacier was rather difficult to traverse up to
the firnlme which was found to be in approx.
1120 m height. During the six days stay on the
glacier, iceather was clear only tiuo half days.
At Valnshamar 'in Grimsvötn the water level
had risen 4.7 m between June 10 and Sept. 10
or on average 5.1 cm per day. At the pit NE
of E Sviahnúkur 262 cm of the accumulation
layer remained, the ablation June 10 — Sept. 10
thus amounting to 194 cm (beside the melting
of the snow that may have fallen during the
surnmer). In the lower part of the rest layer
the water content was 57% against 50% on
June 10.
On the way home from Jökulheimar the
expedition took a run up to Thóristungur, an
oasis between Kaldakvisl and Lake Thórisvatn
and there Thorarinsson measured some soil pro-
files for thephrochronological purposes. During
previous Vatnajökull expeditions a lot of pro-
files has been measured on the way to and
from Jökulheimar, both in the Veidivötn area
and near Landmannalaugar. The preliminary
result is i.a. that the rhyolitic lavaflow Lauga-
liraun is cerlainly prehistoric but hardly more
than 1300 years old. The maar in Tjörvafell,
the lava flow Námshraun and the regular scoria
crater called Stútur may all be younger than
the settlement of Iceland and so is also prob-
ably the crater row Vatnaborgir cutting through
the Veidivötn area between Ljósufjöll and
Svartikrókur.
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