PHYSICAL AND CLIMATAL CONDITIONS. 121 



also have been too much encumbered with ice to allow 

 the formation of heavy waves. 



" The isolated drift higldands of the second plateau, 

 including the Touchwood hills, Moose mountain and 

 Turtle mountain, must also at this time have been formed. 

 With regard to the two former, I do not know whether 

 there is any preglacial nucleus round which drift-bearing 

 icebergs may have gathered. There is no reason to 

 suppose that Turtle mountain had any such predisposing 

 cause ; but it w^ould appear that a shoal once formed, by 

 currents or otherwise, must have been perpetuated and 

 built up in an increasing ratio by the grounding of the 

 floating ice. 



" The Kocky mountains were probably also at this time 

 covered with descending glaciers ; but these would appear 

 to have been smaller than those of the Laurentian axis, 

 as might, indeed, be pre-supposed from their position and 

 comparatively small gathering-surface. The sea, when it 

 reached their base, received from them smaller icebergs ; 

 and by these and the shore-ice the quartzite-drift deposits 

 appear to have been spread. That this material should 

 have travelled in an opposite direction to the greater mass 

 of the drift is not strange ; for while the larger eastern 

 and northern icebergs may have moved with the deeper 

 currents, the smaller western ice may have taken direc- 

 tions caused by surface-currents from the south and west, 

 or even been impelled by the prevailing winds. Some of 

 the Laurentian cUbris, as we have seen, reached almost to 

 the mountains, while some of the quartzite-drift can be 

 distinguished far out towards the Laurentian axis. 



" The occurrence of Laurentian fragments at a stage in 

 the subsidence when, making every allowance for subse- 

 quent degradation, the Laurentian axis must have been 



