144 AZOIC AGE. 



Azoic rocks are now exceedingly uncommon. The whole series 

 has been upturned and flexed, broken and displaced, until little, 

 if any, of it remains as it was when accumulated. 



This upturning, moreover, is not confined to small areas, nor has 

 it been done in patchwork-style ; for regions of vast extent have 

 undergone in common a profound heaving and displacement. 

 This community of action or history is evident in the fact that the 

 rocks have nearly a common strike (§ 113) over wide regions, — the 

 strike being at right angles, or nearly so, to the action of the force 

 causing the uplift. 



The strike in the New York, Canada, Michigan, and Lake Superior Azoic 

 is generally from the northeastward to the southwestward, or nearly parallel to 

 the course of the Appalachians and Green Mountains or the line of the present 

 Atlantic coast. 



In the New York region, according to Professor Emmons, the course of the 

 line of limestone from Johnsburg to Port Henry, on Lake Champlain, is nearly 

 northeast; that of another, along by Rossie (between Black Lake and Pitcairn, 

 and from Theresa nearly to Lisbon and Madrid), north-northeast ; another, paral- 

 lel to this, extends from Antwerp to Fowler and Edwards. These outcrops of 

 limestone follow the line of strike; for the strike of the gneiss is in general 

 from southwest to northeast, or parallel to the general course of the highlands, 

 and therefore of the uplifts. The dip varies from 10° to 90° either side of the 

 perpendicular. The iron-ore beds have the same strike; for all together con- 

 stitute one system. 



In Canada, the limestone ranges of the township of Grenville have the course, 

 according to Logan, between northeast and north-northeast, and mostly the 

 latter. The strike of the gneiss and schists has the same general course. The 

 Azoic near Lake Superior appeal's to have the same mean strike. 



This uniformity of direction attests to a uniformity in the direction or action 

 of the uplifting force, as above remarked. The strike of the Azoic rocks of 

 Scandinavia is also to the northeastward, with no greater variations than occur 

 in the American Azoic : and this common course there, whether connected or not 

 with that on the opposite side of the Atlantic, indicates some vast comprehensive 

 agency as the origin of the disturbance. 



The beds were laid down as sediments over immense continental 

 areas ; and then followed a period of uplift, when the horizontal 

 layers were pressed into folds and displaced on the grand scale ex- 

 plained. Many such periods of uplift may have previously occurred. 

 But it is evident that uplifting and disturbance were not the prevail- 

 ing condition of Azoic times, any more than they were of later 

 ages. This is proved by the conformability of the various Azoic 

 beds to one another in this system of foldings. An age of com- 

 parative quiet, allowing of vast accumulations of horizontal strata, 

 must have preceded the epochs of revolution. 



