Lines of the Giant rantre — West of Silver Mountain. 



BROAD OUTLINES OF THE GEOLOGY OF THE NORTH- 

 WEST OF LAKE SUPERIOR.* 



BY Arthur Harvey. 



So little serious Geological work has been clone to the north of 

 Lake Superior that it is almost a virgin territory, yet this is surely 

 one of the jjivotal points of the geology and geography of the conti- 

 nent. If we look for the governing range, the key to the formation of 

 North-Eastern America, we shall find it in the height of land which 

 runs from a little N. W. of Lake Superior to Labrador. There is 

 no exception to the rule that great heights and depths pi-oduce great 

 geologic and geographic features ; the capes and palisades around 

 Thunder Bay and its vicinity are lofty still — McKay Mountain rises 

 1000 feet, and Thunder Cape 1200 above the water — but this is not 

 nearly all their story ; the great lake near them suddenly deepens, 

 and if one could look up, even now, from the bed of Lake Superior 

 near these points, we should see over 2000 feet of a coast range tower- 

 ing above us, cliff upon clift'; nor can one doubt that this was less, 

 than half, jjrobably less than a fourth of the original height of the 

 Laurentian country there. A map is offered, giving a conjectural 

 outline of the Ai'chsean continent, and I'ising upon this base we may 

 well imagine more than one range of mountains — as lofty, as i-ugged, 

 as the Rocky Mountains of to-day. f 



' This paper was written with special reference to the mining industry of the north 

 shore, and plans of all the working mines and some of the abandoned ones were submitted ; 

 also statistics of production. These the author omits in this abstract, as being of evanescent 

 interest. 



t This map showed a continent extending from the Lake of the Woods to Newfoundland^ 

 The southern boundary ran through the lake country, crossing from Lake Huron to the foot of 

 Lake Ontario, via Lake Simcoe. There was an extension southward from this pomt through 

 New Jersey. It covered most of the country north of the lakes and River St. Lawrence, and 

 the principal mountain chains had an east and west trend. 



