ARCELEAN TIME. 155 



there is direct proof in the gradations as well as in the arrangement 

 in alternating layers, that all the schists and limestone rocks are parts 

 of one series of sedimentary beds, which by some process have been 

 hardened and crystallized. Moreover, there is as direct a j>assage 

 from the gneiss to the gneissoid granite, and thence to true granyte 

 and syenyte ; so that even the most highly crystalline rocks cannot, 

 as a general thing, if at all, be separated from this series. These 

 Laurentian rocks, therefore, are made out of the ruins of older 

 Laurentian, or of still older Archaean rocks, — that is, of the sands, 

 clays and stones made and distributed by the ocean, as it washed 

 over the earliest-formed crust of the globe. The loose material 

 transported by the currents and waves was piled into layers, as in 

 the following ages, and vast accumulations were formed ; for no 

 one estimates the thickness of the recognized Laurentian beds as 

 below thirty thousand feet. Limestone strata occurred among the 

 alternations ; and argillaceous iron-ores, like the beds of the Coal- 

 measures, though vastly more extensive ; and beds of earthy ores of 

 zinc were a part of the formations in the deposits. 



The beds, moreover, were spread out horizontally, or nearly so ; 

 for this is the usual condition with sediments and limestones, when 

 first accumulated. The original condition, then, of the rocks was the 

 same as that of ordinary modern sediments — in horizontal beds and 

 strata. 



Disturbances and Foldings. — But, from the sections and de- 

 scriptions on the preceding pages, it is apparent that horizontal Lau- 

 rentian 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 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 Archaean is 

 generally northeastward, or nearly parallel to the course of the Appalachians and 

 Green Mountains, but varies to north, and also to east. 



In the New York region, according to 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, parallel to this, extends from Ant- 

 werp to Fowler and Edwards. These outcrops of limestone follow the line of strike. 

 The dip varies from 10° to 90°, either side of the perpendicular. The iron-ore beds 

 have the same strike; for all together constitute one system. 



In Canada, the limestone ranges of the township of Grenville have a course, ac- 



