SUPEKFICIAL GEOLOGY OP BRITISH COLUMBIA. 95 



the hardest cutting-material available to the ice, portions of rock 

 containing quartz in their composition show great powers of endu- 

 rance compared with those consisting of felspar and hornblende only, 

 though the latter may be quite as compact. Instances where quartz- 

 ose intrusions protect long southward-pointing ribs or pencils of 

 diorite are not rare. 



There appears to be no escape from the conclusion that a glacier 

 swept over the whole south-eastern peninsula of Vancouver Island 

 at some time during the Glacial period ; and on consideration of the 

 physical features of the country it becomes apparent that the entire 

 Strait of Georgia between the island and the mainland must have 

 been filled with a great glacier, with a width, in some places, of over 

 fifty miles, and a thickness near Victoria of at least considerably over 

 600 feet. With all this, however, there has been very little general 

 wearing-down of the rock-surface of the country; all its main 

 features, and, in many cases, even the most minute, are clearly of 

 preglacial origin. The valleys generally follow bands of limestone 

 and softer schistose and shaly beds, and run as often transverse to, 

 as parallel with, the direction of glaciation ; and besides the general 

 forms of the smaller hills, little rocky knolls and projecting points 

 of rock, while worn and rounded to the north, preserve rough un- 

 polished southern faces. This feature is more marked than I have 

 elsewhere observed, and would seem to indicate, even allowing that 

 glaciers do not very rapidly abrade solid rocks, that the ice did not 

 long rasp over this portion of the country, and possibly that it never 

 extended much beyond this point. 



Mr. George Gibbs mentions the occurrence of glacial grooving 

 running from north-east to south-west, on San- Juan Island, in the 

 southern part of the Strait of Georgia, which would appear to show 

 that the glacier must have pushed southwards towards the low country 

 of Puget Sound, while a part may also have discharged westward 

 into or through Fuca's Strait. Glacial striation is also reported on 

 the mainland shore of the southern part of the Strait of Georgia. 



b. Superficial Deposits. 

 The detrital deposits overlying these glaciated rocks are of a com- 

 paratively simple character. In the immediate neighbourhood of 

 Victoria, near the sea-level, a material which I believe to represent 

 moraine profonde occurs in a few localities, as a hard mass of sandy 

 clay and stones, wedged into crevices in the rock, or protected by 

 its overhanging ledges. Further inland, in the valleys of the Gold- 

 stream, Leech, and Sooke rivers, and small brooks tributary to them, 

 a very similar material forms the greater part of the drift, and rests 

 on rock-surfaces which, though generally smoothed, have only been 

 observed to show direction of movement in the single locality already 

 mentioned. Those valleys are deep, V-shaped in cross section, gene- 

 rally surrounded by rocky hills, and often transverse to the course 

 of the ice ; and they must have formed receptacles which, in course 

 of time, were more or less completely filled with bottom-moraine, 

 the remnants of which I believe the material above mentioned to 



