PLEISTOCENE VULCANISM OF BRITISH COLUMBIA 263 



plateau on the south side of the valley of Garibaldi Lake. This 

 basin consists of a wall of granite, inclosing the cone on its west and 

 southwest sides and a summit standing out on the east side of the 

 cone which is composed of the older Miocene andesite. This also 

 appears to form the floor upon which the volcano stands. This 

 basin is probably a glacial cirque. It is now almost completely 

 filled up by the volcano, but some small areas of its floor which are 

 exposed on the north side appear to have been almost certainly 



Red Mountain 

 Mount Garibaldi East Cone West Cone 



Fig. I. — Mount Garibaldi and Red Mountain from the north. Garibaldi Lake in 

 the foreground. The lava flow which dams it is to the right, beyond the picture. 

 The old trunkated flow described is in the foreground. The flat-topped mountain in 

 front of Mount Garibaldi is Table Mountain, which is composed of Miocene lavas. 



glaciated. It might otherwise have been attributed to explosive 

 action in the early stages of the vulcanism, but there are no f rag- 

 mental materials around its margin which would confirm this. 

 The inner wall of the basin shows no evidence of glacial polishing, 

 while the plateau above is well striated by the first glaciation. The 

 basin seems, therefore, to have originated at a time later than the 

 first glaciation, and is probably a cirque formed during its retreat 

 or during the second period of ice-advance. The beginning of the 

 volcanic activity must therefore also be dated subsequent to the 

 first glaciation and perhaps later than the beginning of the second 

 glaciation, if time must be allowed for the formation of the cirque. 

 Neither of the two cones show any evidence of having been over- 

 ridden by ice at any time. The older cone lies to the east. It is 



