130 NEW YORK STATE MUSEUM 



is more intense near the eastern margin of the continent than in its 

 interior. It could therefore be assumed as a working hypothesis 

 that the Precambrian continent of North America which, as we have 

 shown before, developed a uniform system of folding, that was convex 

 southward and in the east and west parallel to the Atlantic and 

 Pacific oceans, was affected simultaneously and through an immense 

 lapse of time from these three sides by pressure that beginning 

 its orogenic activity near the coasts led gradually to the continuous 

 system of folds extending over the whole continent. Similarly 

 the Precambrian folding of Eurasia could be conceived to have begun 

 near the Pacific and Atlantic coasts and gradually wandered inward, 

 until the two systems of folds met at the Baikal line. 



There are also certain more general views regarding the origin 

 of the folds recorded in the literature that would seem to support 

 the possibility of a gradual development of the Precambrian folding 

 near the coasts. Foremost among them, is the hypothesis advanced 

 by Reyer (1894) and Andree (19 14, p. 69) that the deeper cause for 

 the form of the mountain ranges is to be found in the fact that the 

 boundaries of the oceanic and continental crust portions favor the 

 formation of the bands of geosynclines and mountain ranges and that 

 the curved form of the latter, which some would attribute to torsional 

 effects, is therefore the consequence of the curved outlines of the 

 coasts near which the mountain ranges originated. Willis (1907, 

 p. 117) holds a similar view, when he states that, " since progressive 

 subsidence results in the development of initial dips in lines essentially 

 parallel to the coast, and since initial dips determine the axial 

 directions of folds during the next epoch of deformation by horizontal 

 stress, it follows that the axial directions of folds conform to the 

 general contour of the higher continental elements, to the land 

 masses." 



If this conception of the relation of the mountain ranges to 

 the original coast lines is correct, it gives us a fair suggestion of 

 the principal coast lines of Archi-America (from north to south in 

 the west; northeast in the east; and .possibly east-west in the south) 

 and Archi-Eurasia (northeast in the east and northwest in the west) ; 

 while Archi-Gondwana would suggest north-south coast lines both 

 in the east and the west. As a matter of fact, these coast directions 

 do indeed well agree with the supposed positions of the primeval 

 oceans, the Poseidon (the present central Atlantic) and the Archi- 

 Pacific ocean. 



Another view that is favorable to the hypothesis of rather a 

 gradual extension of the Precambrian folding instead of a simul- 



