294 The American Geologist. May, is99 
again, a true mountain lake with rocky shores, though very 
unHke the upper lakes. Near the head of this lake the last 
mountain peaks and ridges are seen; lower down all the 
hights to an elevation of 2,000 feet above the valley are round- 
ed and at least as regards the lower ones polished in a manner 
that can scarcely have arisen otherwise than by glacial erosion, 
a supposition which is not contradicted by some of the hights, 
sugar-loaf in shape, consisting of masses of limestone. Glacial 
striae from this part have been described by several explorers, 
and Russell was led to assume by their fresh appearance that 
the glacial period could not have been very distant in date. 
The lake itself is of a considerable depth. At one point I 
found a depth of 360 feet, while at its center it is probably deep- 
er still. 
To explain the origin of these lakes resort can be had to 
four theories: they were either excavated by ice, or arose 
through faults in the rocks, or were dammed by unequal fold- 
ing, or by deposition of morainic material. The last theory is 
untenable seeing no moraines of the requisite extent have been 
found either in the valley of the Lewes river or in the Ogilvie 
valley, the topographical continuation of lake Lebarge. I 
made an excursion up the last mentioned and hitherto unvis- 
ited valley for some 20 miles, finding everywhere the same 
white silt that occurs also so plentifully in the river valley. The 
idea that this silt could under present topographical circum- 
stances have dammed up such a large lake is inconceivable. 
Nor does the dislocation theory commend itself, at any rate as 
regards the majority of the lakes, for then a straighter course 
in the valleys would have been probable, and greater differ- 
ences in the rocks adjacent on either side of them and in their 
beds as compared with the hights around. A combination of 
ihe two remaining theories strikes me as most probable. It is 
to be ])resumed that the glacial erosion was excessive, but if it 
had hollowed out all these basins we should have expected to 
find traces of it in the shape of much more extensive moraines 
than those actually found. P^lication and subsidence in con- 
junction with ice-loading, possibly united with dislocation to 
some extent, would therefore seem to be the principal agents in 
the production of these valleys. Russell seems to advocate a 
similar theorv. 
