Jökull - 01.12.1967, Page 56

Thoroddsen does not in his thorough destrip-
tion mention any ice bergs on the lake so the
water can be supposed to have been shallow
at the glacier margin. The foremost terminal
moraine most likely dates from this time. The
upper shoreline extends up to this moraine and
therefore cannot be younger.
There are no sources of information avail-
able as to the conditions at the north-eastern
end of the lake from the time of Thoroddsen’s
travelling there up to the time of the surveying
by Geodetic Institute in 1937. The map and
the aerial photo frorn wliich it is complied are
so inaccurate as regards the glacier margin that
it is impossible to determine its exact location
at that time, but somewhere between the outer-
most and the middle terminal moraines is a
probable location. The map seems to represent
the north-eastern shore of the lake with ap-
preciable exactness as indicated by various
easily recognizable characteristics. The position
of the shoreline in 1937 is illustratecl in Fig.
7B.
In the year 1946 Langisjór was aerially photo-
graphed in connection with mapping l)y the
U.S. Army Map Service. The photographs and
the map show that the shore had by tlien
extended out 50 to 500 m and a small lake
had been formed in a nook against Tungnaár-
fjöll. By then the glacier margin was lying at
the uppermost moraine, cf. Figs. 6A and 7C.
The next sources of information as to the
conditions at the north-eastern end of Langi-
sjór are aerial photographs taken in 1959 ancl
maps produced after them. Aerial photographs
from the year 1960 are also available. In 1960
the glacier margin had become thin ancl stagn-
nant ice had begun to develop behind tlie
uppermost terminal moraine. A greater part of
the glacier water still clrained into Langisjór,
but frorn the pass that had opened between
the glacier and Fögrufjöll a branch had begun
Fig. 6. Two areal photographs showing the northeastern part of iake Langisjór. A is taken
in the year 1946 and B in 1960.
Mynd 6. Tvœr flugljósmyndir, sern sýna norðausturhluta Langasjóar. A er tekin árið 1946 og B
árið 1960.
290 JÖKULL 17. ÁR