Jökull - 01.12.1990, Page 63

from the southem lowlands to Kjölur. He did not
find any real end moraines nor other signs of a former
glacier margins there, but assumed ”the ice margin
must have been at the south-eastem slope of Bjamar-
fell and Sandfell, but its remnants have not been inves-
bgatedyet“ (Kjartansson, 1961). Laterheassertedthis
without further arguments referring to former state-
ments (Kjartansson, 1964a). Sæmundsson (1965) did
not object to what Kjartansson maintained about the
position of the ice margin, and consequently had to
assume higher age of the deglaciation in the Þing-
vallavatn area.
Based upon Kjartansson’s data, Einarsson (1961)
postulated that the main ice divide between North and
South Iceland was situated some 20-30 km to the south
of the present watershed, not only during the deglacia-
tion period but throughout the Weichselian glaciation.
Later as more data had been gathered on the Þjórsá-
Tungnaá area, Einarsson (1964) transferred this main
ice divide southwards, about 50 km to the south of
the present watershed. Einarsson (1967) agrees with
Kjartansson on the above described position of the
glacier margin and used it to reconstruct the position
of the Younger Dryas glacier margins. Furthermore
he was convinced that the Langjökull mountains were
ice free at the time of the ice front lake in the Kjölur
area.
Sigbjamarson (1967) mapped part of the Hauka-
dalsheiði moraines and proved that the above men-
tioned position of the ice front could not be true. The
data presented on Fig. 9 support his view and show
that the deglaciation of the Kjölur area occurred later
than the withdrawal from the Búði end moraine.
CONCLUSIONS
During the climatic deterioration in the beginning
of the Weichselian, glaciation limit was lowered and
ice caps formed on the highest mountains. Glaciers
from the relatively high mountainous areas in South
Iceland reached the sea within a short distance and
further expansion was limited by calving. In the in-
land areas the distance to the shore was much greater
and the ice thickened. The oldest sets of striae always
points away from the centre of the highlands indicating
a culmination area somewhere near the present water-
shed at the beginning of the deglaciation and probably
also at the maximum of the Weichselian glaciation.
This is in good agreement with what is known about
the growth of ice sheets such as the Scandinavian ice
sheet (Flint, 1971; Lagerlund, 1987).
Figure 10: Deglaciation of Central Iceland and tentative reconstruction of the main ice sheet at different times.
Arrows indicate ice movement direction. An attempt is made to show similarity in age of the end moraines. A.
The Búði end moraines formed in front of two ice-lobes in the valleys of Hvítá and Þjórsá rivers 9750-9600
years ago. B. The Blanda moraines are possibly of similar age as the northemmost moraines N of Hofsjökull.
C. The Haukadalur moraines are little older than the moraines E of Hvítárvatn. Some of the end moraines NE
°f Hofsjökull could be of similar age. Some ice remains in the Langjökull area. D. The moraines N of Þjórsá
are possibly of similar age as the southemmost moraines E of Hofsjökull. Some glacier flow was still from the
Hofsjökull area. E. In the very last stage of the recession glacier flow was to NW and N from a late glacial
íce divide close to lake Langisjór. —Jökulhöifun á miðhálendi Islands og hugsanleg lega jökuljaðars á hinum
ym.su stigum. Örvar sýna skriðstefnu. Líkum er leitt að svipuðum aldri jökulgarða. A. Jökuljaðarinn lá við
Búðagarðana á Suðurlandi fyrir 9750-9600 árum. Jökullinn skreið í tveim tungum eftir farvegum Hvítár og
Þjórsár. B. Jökulgarðar A Blöndu gœtu verið af svipuðum aldri og nyrstu garðar N Hofsjökuls. 5C. Garðar á
Haukadalsheiði eru lítið eldri en garðar A Hvítárvatns. Ekki er vitað hvaða garðar A Hofsjökuls eru jafnaldra
þessum. Einhver jökull er enn á Langjökulssvæðinu. D. Garðar N Þjórsár tengjast hugsanlega syðstu görðum
A Hofsjökuls. Jökulstreymi varfrá Hofsjökli á þessum tíma. E. Síðast skreið jökull til NV og N frá ísaskilum
sem þá lágu rétt N Langasjávar.
JÖKULL,No. 40, 1990 61