Jökull - 01.12.1990, Side 57

Figure 5: Glacial di-
rectional features in the
Kjölur area. For legend,
seeFig. 2. -—Skriðstefna
jökuls og jaðarmyndanir
á Kili. Sjá skýringar á
mynd 2.
somewhat to the south of the present watershed, a lake
was formed in front of the glacier, which drained to
the north towards river Blanda. Kjartansson (1964a)
described the history of this lake and the contempora-
neous volcanic events. Tómasson (1967, 1987) con-
nected various flood indications in the vicinity of river
Hvítá to catastrophic floods from this lake.
Terraces at about 640 m a.s.l. mark the highest po-
sition of the lake level. When the glacier retreated fur-
ther south, the lake was drained towards SW along the
slopes of the Langjökull mountains. Several distinct
shorelines in the slopes of Leggjabrjótur and many
other places mark the lake level at different stages.
In spite of the prominent terraces bottom sediments
seem to be absent, which raises the question whether
this lake was more than a narrow strip between the ice
front and higher ground.
The area along the northern hank ofÞjórsá above
mount Búrfell — The oldest indication of a former
glacier margin is a short but very prominent end
moraine near the Háifoss waterfall in the river Fossá
(Fig. 4, Kaldal and Vilmundardóttir 1986). This
moraine can not be traced any further. The direction of
the oldest striae behind the end moraine is towards S W
but the younger ones has a NW direction, transverse
to the end moraine.
To the north of river Þjórsá, from Fitjaskógar
to Norðlingaalda, there is a successive row of end
moraines (Fig. 6). The most prominent are the three
moraines at Fitjaskógar, which can be traced over 20
km to the north. Glacial striae and direction of flutes
indicate westerly ice movement. As the glacier re-
treated, the ice movement direction shifted progres-
sively towards NW. The oldest striae show movement
towards SW and the youngest indicate movement to-
wards W or NW.
This westerly and northwesterly direction of
movement is somewhat contrary to the topography.
JÖKULL, No. 40, 1990 55