Jökull - 01.12.1967, Blaðsíða 4

In the year of 1951 cooperation started be-
tween the Iceland Glaciological Society and
the French Greenland expedition headed by
P. E. Victor on measurements of the thickness
of the ice cover of Vatnajiikull iry seismic
sounding metliods (Eyihorsson 195la, 1951b).
In 1955 Vatnajökull was the only ice shield
in Iceland whose thickness was known. Good
cooperation with the Frenchmen hacl been
kept and now they provided, as before, a
scientist and the necessary instruments. Regard-
ing equipment and technique the reader is
referred to Holtzscherer (1954). A preliminary
report of the results obtained during the ex-
pedition has already been given (Thorarinsson
and Rist 1955) but the final report of results
has been delayed because geodetic data were
lacking.
THE MÝRDALSJÖKULL AREA
The southernmost ice shields in Iceland are
Eyjafjallajökull and Mýrdalsjökull situated on
the same mountain complex. They were join-
ed until recently, but during the years 1950/60
they were finally disrupted due to the general
retreat of these two ice covers. Now there is
a snow free area between them every summer.
The area of Mýrdalsjökull is nearly 700 km2
and that of Eyjafjallajökull close to 100 km2.
Moist winds blowing across the Atlantic Ocean
from easterly, southerly and westerly directions
cause heavy precipitation on these ice covers.
On the contrary northerly winds are relatively
dry and do not cause much precipitation. Mýr-
dalsjökull is a temperate ice shield as in fact
all other ice shields in Iceland at present
(Rist 1960).
The volcano Katla had not been accurately
located under the ice cover hefore the 1955
expedition. Ice covers the eruptive fissure
shortly after each eruption leaving no traces
of it. During the 1955 expedition the location
of Katla became a little clearer. Its location
is shown in Fig. 1 (drawn from the Icelandic
topographic maps no. 58, 59, 68, and 69, with
corrections made by Steinthor Sigurdsson in
1943).
EXPEDITION
The expedition set out onto the ice shields
in two weasels on June 19, 1955. The route
lay along the eastern side of Sólheimajökull
coming onto the ice cover in Hólsárbotnar. The
same route was followed on the way back, on
June 27.
The following participated:
Jean Martin (French scientist)
Jón Eythorsson (meteorologist)
Gudmundur Jónasson (driver)
Sigurdur Thorarinsson (geologist)
Sigurjón Rist (hydrologist, leader).
The base camp was set up in the depres-
sion northwest of Háabunga and southeast of
Godabunga (Station 1 in Fig. 1). The weather
was bad and visibility poor causing much delay
in the seismic sounding work.
While the expedition stayed on Mýrdals-
jökull a jökulhlaup occurrecl and two cauldrons
were formed in it. This jökulhlaup will be
treated in the succeeding article.
RESULTS
a) The thickness of Mýrdalsjökull: Tlie main
purpose of the expedition was to measure the
thickness of the ice cover. The data obtained
is presented in Table I (see also Fig. 1).
Fig. 1. A map of Mýrdalsjökull. Seismic soundings were performed in Pi to Po (Table I). The
two cauldrons which formed simultaneously with the jökulhlaup on June 25, 1955 are shown.
Tracks for weasels from Sólheimakot and the climbing route from Heidi to the ice cauldrons
are indicated. Directions from the village Vík to the eruption cloud of Katla in 1918 are also
drawn on the map.
Mynd 1. Kort af Mýrdalsjökli. I punktum Pi til Po var mceld þykkt íssins (Tafla I). Sýnd eru
ketilsigin tvö, sem mynduðust samtímis jökulhlaupinu 25. júní 1955. Merkt er snjóbilaleið frá
Sólheimakoti inn á jökul og gönguleið frá Heiði um Koltungur að ketilsigum. Ennfremur eru
teiknuð á kortið mið, sem tekin voru frá Vik á gosmökkinn 1918.
238 JÖKULL 17. ÁR