Jökull - 01.12.1966, Page 53

SIGURDUR THORARI NSSON :
The Age of the Maximum Postglacial Advance
of Hagafellsjökul eystri
A Tephrochronological Study
In my paper “Some Tephrochronological
Contributions to the Volcanology and Glacio-
logy of lceland” published in 1949 I presented
a soil profile measured on the east side of a
soil patch situated only a few metres in front
of the most advanced terminal moraine of
I-Iagafellsjökull eystri, W of the present bed of
the river Far (cf. Fig. 1). This profile is shown
as profile 2 on Fig. 2. The profile showed
that here the soil format.ion had been undis-
turbed by ice since the ice margin receded
from this place in early postglacial times, thus
proving that the terminal moraine which near-
ly touches the abovementioned soil patch and
was very near the glacier margin in the early
1920ies, marks the maximum extension of
Hagafellsjökull eystri in postglacial times.
In the triangle between the Far river-beds of
1929 and 1939 and E of Brekknafjöll loessial
soil can be seen underneath the ablation mo-
raine of the retreating glacier. During my visit
to this area in 1948 — 1 was then leading an
excursion of Swedish geographers — I observed
that layer H4 was undisturbed in the soil,
which proved that the erosional power of the
glacier had been very limited, but I had no
time for a closer look at the soil and conld
only tell that the advance of the glacier over
it had taken place after the deposition of
layer H4, which is 4000 vears old (Thorarins-
son 1949).
During the summer of 1950 a student expedi-
tion from Durham University worked a few
weeks in the Hagavatn area. One of the parti-
cipants, R. Green, intended to study the varved
lake sediments in those parts of the Hagavatn
lake basin that had been emptied by the cata-
strophic drainages (jökulhlaup) in 1929 and 1939,
Fig. 1. Lake Hagavatn
and the glacier Hagafells-
jökull eystri according to
aerial photographs taken
1960 by the Icelandic Sur-
vey Department. Broken
lines show the max. ex-
tension of the glacier in
postglacial times.
Hagavaln og Hagafells-
jökull eystri samkvœmt
flugmyndum frá sumrinu
1960. Þyklia brotalinan
sýnir m.estu útbreiðslu
jökulsins eftir isaldarlok.
JÖKULL 207