Jökull - 01.12.1964, Blaðsíða 9

SIGURDUR THORARI NSSON :
On the Age of the Terminal Moraines
of Brúarjökull and Hálsajökull
A Tephrochronological Study
THE TERMINAL MORAINES
OF BRÚARJÖKULL
In 1962 I was invitecl by two professors of
the University of Iceland, Kristinn Stefánsson
and Snorri Hallgrímsson, to join them on a trip
to Kringilsárrani north of Brúarjökull in late
August that year. They were going to this
area in order to study supposed disease in the
reindeer stock living wild there as the area
is protected by the two large glacier rivers
Kringilsá ancl Jökulsá á Brú. I gratefully ac-
cepted this invitation, as it gave me an op-
portunity to fill a gap in my tephrochrono-
logical knowleclge of the postglacial soils in tlie
interior of Iceland. I was also eager to have
a look at the „Vorfeld" of Brúarjökull in this
area, well known in the glacial-geological
literature, especially through the investigations
of Hannesson (1953), who visited Kringilsár-
rani in 1933, Woldstedt (1939), who was there
in 1936, and Todtmann (1955, 1957, 1960), who
spent the summer of 1955 in this very interest-
ing area.
The rnost striking topographical features of
Kringilsárrani are high terminal moraines (max.
relative height 18 m) covered by relatively
luxuriant vegetation. These moraines are typi-
cal thrust moraines, showing complex folding
and overthrusting. E. Kjerulf, who wrote a con-
temporary report on the 1890-advance (cf.
Jökull 1962, pp. 47—48) calls such moraines
jökulýtur, which is an excellent terrn. The local
name for the vegetation-covered thrust moraines
is hraukur, plur. hraukar. Thev stretch not
only over Ivringilsárrani, but continue, mainly
as block moraines, towards W to Kverkárnes
and towards E to Maríutungur. No doubt they
are mainly formed by the catastrophic advance
of Brúarjökull in 1890 (op. cit.), but in some
places their distal part may have been formed
by the catastrophic advance in 1810, and push-
ed a little farther northwards by the 1890-
advance. This seems to be the case in Kringils-
árrani, according to contemporary descriptions
of the 1890-advance. East of Jökulsá there are
some “hraukar”, such as Útigönguhaus south
Fig. 1. Sketch map showing the situa-
tion of profiles cliscussed in the text
in relation to the terminal moraines of
1890 and 1810. Schematized witli some
alterations by the author from the ntaps
Fig. 2, Todtmann 1957 ancl Fig. 5, Todt-
mann 1960.
JÖKULL 1964