LAKES AND VALLEYS OF NUGSUAK PENINSULA 659 
decayed rock, and perhaps to deepen the depressions formed by this action, 
though ice erosion would not in this case be the prime cause for the basin. 
These [ rock-basins] seem to be depressions caused rather by preglacial 
decay than by glacial erosion, They are oftenso small and bounded by walls 
so angular that origin by ice scouring seems impossible." 
The valley lakes.—The line, marked ‘‘AB” on the map, indi- 
cates the position of one of the largest valleys on the peninsula, 
with seaward termination on the east and west sides, and is from 
three and a half to four miles in length. Fig. 3 shows cross- 
sections, with reference to sea level, of the east and west ends of 
this valley. ‘‘A’”’ was sketched at a point in the valley 165 feet 
above sea level, while “‘B” is only 15 feet above. Neither of 
these has been platted to any scale. A glance at the two is 
sufficient to note the contrast in outline of the two ends of the 
valley. The south end, A, is filled in on all sides to an unknown 
depth with perfectly angular blocks of large dimensions. This 
difference in valley width for the two ends is due, probably, in 
a great measure, to preglacial conditions. It is more than likely, 
that the preglacial divide was located near the south end of the 
valley, with its western end farther down stream, and therefore 
wider. The west end of the valley is fully three fourths of a 
mile wide, with inclosing walls rising 1000 feet and more above 
the bottom, sloping at a steep angle—less than 45°. 
The valley further holds the largest lakes distributed along 
any one of the valley bottoms (see Fig. 2). Careful soundings 
were made of all the lakes located in this valley, and two showed 
their bottoms to be considerably below sea level. The position 
in the lakes where soundings were taken are marked on Fig. 2. 
After the sounding data were obtained, several possibilities 
naturally suggested themselves to account for this condition, in 
the lakes. A close examination of all the conditions, however, 
resulted in the elimination of all save one of the possibilities. 
Stream erosion with subsequent depression is eliminated on the 
ground of extreme irregularity of valley bottom. On the north 
and near the west end of the valley, the attitude of the strata is 
1 /bid., Bull. Geol. Soc. Amer. 1897, Vol. VIII, p. 255. 
