THE LAUEENTIAN EOCKS. 



and to this as the grandest and most 

 instructive development of them, and 

 that which first afforded organic re- 

 mains^ we may more especially devote 

 our attention. Their general relations 

 to the other formations of America 

 may be learned from the rough gene- 

 ralised section (fig. 1) ; in which the 

 crumpled and contorted Laurentian 

 strata of Canada are seen to underlie 

 unconformably the comparatively flat 

 Silurian beds, which are themselves 

 among the oldest monuments of the 

 geological history of the earth. 



The Laurentian rocks, associated 

 with another series only a little 

 younger, the Huronian, form a great 

 belt of broken and hilly country, 

 extending from Labrador across the 

 north of Canada to Lake Superior, 

 and thence bending northward to the 

 Arctic Sea. Everywhere on the lower 

 St. Lawrence they appear as ranges 

 of billowy rounded ridges on the 

 north side of the river ; and as viewed 

 froni the water or the southern shore, 

 especially when sunset deepens their 

 tints to blue and violet, they present 

 a grand and massive appearance, 

 which, in the eye of the geologist. 



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