KIvISHA MITCHKr.Iv SCIENTIFIC SOCIETY. 41 



east of the New Eng-land section during- Cambrian 

 times, leads to a conjecture which may here be stated. 



A persistent and connected series of Cambrian out- 

 crops lies along- the Appalachian mountain S3^stem from 

 Alabama to the river St. Lawrence. These are known 

 to have been deposited in the g-reat continental sea 

 which covered the central portion of North America 

 during- the whole of Paleozoic time and even later. These 

 Cambrian rocks with the other Paleozoic sediments 

 were involved in the orog-raphic movement which g-ave 

 rise to the Appalachian mountains. Their present 

 outcrop, however, is adjudg*ed to mark in a g-eneral way 

 the eastern border of the continental sea in which the}^ 

 were deposited. To furnish this enormous thickness of 

 Paleozoic sediments a much larger land area must 

 have existed toward the east than now remains. The 

 fact that the denuded surface of much folded pre- 

 Cambrian rocks is seen now to disappear eastward 

 under the present continental shelf, in some measure 

 bears out this idea. 



The conjecture now follows, that the Cambrian 

 rocks of New Eng-land heretofore described as belong- 

 ing- to the Atlantic coast province form really a part of the 

 Appalachian province; that is, that they were deposited 

 not in the Atlantic, but, along- with the not far distant 

 Cambrian rocks of eastern New York in the continen- 

 tal sea. This satisfies the conditions which have been 

 predicated of them, namely, that the}' were deposited, 

 not in the open ocean, but in a more or less sheltered 

 sea. The elevation of a part of this area in the pro- 

 cess of Appalachian mountain building- and the subse- 

 quent denudation of the whole of New Eng-land, reduc- 

 ing- it almost to base-level, would account for the 

 existence of the Cambrian rocks only in isolated 



