96 



SKETCHES OF CREATION. 



lines. In its upper angle lies Hudson's Bay, whose place 

 was designated as soon as it became the bottom of a sub- 

 marine valley. The southern slope of the ridge became 

 the water-shed which was to supply the great lakes and 

 the St. Lawrence. The St. Lawrence finds its outlet to the 

 ocean in a valley parallel with the ancient ridge. The pe- 

 culiar notch from Georgian Bay to the head of Lake Erie, 

 and thence to the Niagara River, is conformed to the sal- 



Fig. 39. Hydrographic and Orographic Outlines of North America. 



lent angle of the same ridge. The " great lakes" them- 

 selves are but links in the vast chain of lakes extending to 

 the Northern Ocean, accumulated in a valley inclosed by 

 the western branch of the continental nucleus on the one 

 hand, and the occidental ridge of the continent on the 

 other. The Mississippi pursues its course along the bot- 

 tom of the depression between the Appalachian and Rocky 

 Mountain ridges, while the McKenzie — the Mississippi of 



