Jökull


Jökull - 01.12.1964, Blaðsíða 9

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

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Jökull

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