36 THE CANADIAN NATURALIST. [Vol. ix. 



line of the 49th parallel, notwithstanding the generally mountain- 

 ous character of that part of the region. Travelled boulders 

 and stones rounded by water action are found at like heights 

 with the striation, occurring even at the summit of Iron Moun- 

 tain ; and over the greater portion of the region, from the eastern 

 slopes of the elevated land of the coast ranges, is spread a cover- 

 ing of drift material, more or less abundantly charged with 

 erratics, and where not modified by water action subsequent to 

 its deposition, to be referred to the boulder clay. Terraces, or 

 " benches," are in many places in this part of the province shewn 

 in wonderful perfection, rising tier above tier from the bottoms 

 of the valleys, till they are found in a more or less wasted state 

 encircling the higher portions of the plateau remote from the 

 river-courses. These in several places exceed 3500 feet in 

 altitude above the level of the sea, but none so high as that 

 previously observed on Il-ga-chuz Mountain, in the northern part 

 of the province, were found. 



In the valleys connected with the Thompson, and especially 

 about Kamloops Lake and the valley of the South Thompson 

 above Kamloops, but also in the great Okanagan Valley, and 

 forming small outlying patches for some distance up the Similka- 

 meen, is a remarkable horizontally-stratified deposit of white silt, 

 in the form of terraces. These are evidently remnants of a sheet of 

 similar material, which has at one time formed the floor of these 

 wide trough-like valleys. In composition it resembles the white 

 silts of the Nechacco Basin, but occurs at a different horizon, 

 reaching a maximum height, so far as ascertained, of about 1700 

 feet above the sea. In origin it is probably like that of the 

 Nechacco, a deposit from the turbid waters of glaciers at a time 

 when the ice still had a considerable extension from the various 

 mountain ranges, and general depression of the land, or the 

 damming up of the valleys gave rise to a system of winding 

 water-ways — lakes or fjords — which occupied the main depres- 

 sions of the surface. The heads of these valleys, in the flanks 

 of the Gold Range, still hold long and deep lakes, on the bank^ 

 of which drift deposits appear to be scarce and the white silts 

 are not found. I refer in this connection particularly to the 

 system of valleys occupied by the Shuswap Lakes. It appears 

 not improbable that at the time the white silts were laid down 

 the portions of the valleys now held by these lakes were filled 

 with glacier ice, and that eventually a rather rapid dissolution 



