MODERN GEOLOGY 



once lay above them have been worn away. All that 

 the cautious geologist dare assert, therefore, is that the 

 region in question did not become permanent land sur- 

 face earlier than the Devonian age. 



But to know even this is much sufficient, indeed, to 

 establish the chronological order of elevation, if not its 

 exact period, for all parts of any continent that have 

 been geologically explored understanding always that 

 there must be no scrupling about a latitude of a few 

 millions or perhaps tens of millions of years here and 

 there. 



Regarding our own continent, for example, we learn 

 through the researches of a multitude of workers that 

 in the early day it was a mere archipelago. Its chief 

 island the backbone of the future continent was a 

 great V-shaped area surrounding what is now Hudson 

 Bay, an area built up, perhaps, through denudation of a 

 yet more ancient polar continent, whose existence is 

 only conjectured. To the southeast an island that is 

 now the Adirondack Mountains, and another that is now 

 the Jersey Highlands rose above the waste of waters, 

 and far to the south stretched probably a line of isl- 

 ands now represented by the Blue Ridge Mountains. 

 Far off to the westward another line of islands fore- 

 shadowed our present Pacific border. A few minor 

 islands in the interior completed the archipelago. 



From this bare skeleton the continent grew, partly 

 by the deposit of sediment from the denudation of the 

 original islands (which once towered miles, perhaps, 

 where now they rise thousands of feet), but largely also 

 by the deposit of organic remains, rsjvrially in the- in- 

 terior sea, which teemed with life. In the Silurian 



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