Jökull - 01.12.1982, Page 42

Fig. 1. Location of Breida-
merkurjökull and Jökulsárlón.
Mynd 1. Breiðamerkurjökull og
Jökulsárlón.
THE FORM AND HISTORY
OF JÖKULSÁRLÓN
A bathymetric survey of the lake was undertaken
in summer 1975. Twenty-two straight-line echo-
sounding runs (Fig. 2) were made in a 6 m boat
powered by a 20 H.P. motor. The beginning and
end of each run were accurately fixed. Flags at these
points allowed a near straight-line course to be
steered, and points along the run were checked by
sextant. This, together with good agreement at pro-
file crossing points minimised the horizontal error,
which we estimated to be about ± 20 m. The echo-
profiles were made using a high resolution Simrad
EY echo-sounder with a maximum checked error of
± 2% at a depth of 60 m and ± 3% at 120 m.
The resultant bathymetric map is shown in Fig. 3,
and a hypsographic curve of volume and area in
Fig. 4. The basin has steep margins and a flat floor
between 85 and 90 m below sea level, and lacks the
bench forms described by Howarth and Price (1969)
from nearby Breidárlón.
For comparative purposes some morphometric
parameters are set out in Table 1. These are com-
pared with values of Dl and z/zm for several North
American Lakes which belongtoHutchinson’s (1957)
type 28, which he believes owe their origin to “glac-
ial corrasion“. The z/zm values, are very similar for
Jökulsárlón, however, the DL values are much
smaller for Jökulsárlón. This reflects the lake’s
youth, as near-shore erosional prosesses have not yet
been able to cut coastal platforms.
Fig. 2. (a) Location of echo-sounder traverses in
Jökulsárlón.
(b) Location of Sparker traverses.
Mynd 2. Mælilínur á Jökulsárlóni.
a) dýptarmtelir b) neistatœki.
38 JÖKULL 32. ÁR