Jökull - 01.12.1965, Blaðsíða 24

Fig. 1. The almost parallel glacial spillways on the Hestháls ridge between Lundarreykja-
dalur and Skorradalur. The steepest gradients occur on the northern (Lundarreykjadalur) ends
o£ tlie spillways.
this area by Thorarinsson (1951), but others are
simply shelves cut on the hillsides.
III
At one time the spillway type o£ channel was
considered to be one indication of the exis-
tence of pro-glacial lakes (see Kendall, 1902),
but modern work by Mannerfelt (1945) and
Sissons (1958) lias shown that many of these
features can be caused by drainage under the
glaciers or icecaps, where hydrostatic pressure
may be sufficient to cause water to flow over
130 JÖKULL