68 NEW YORK STATE MUSEUM 



entirely out of his chosen field of investigation. This paper is 

 largely intended to direct attention to the possibility of going beyond 

 the Cambrian paleogeography and to invite to the task others who 

 are more competent to do so. 1 



It is our purpose, at present, to survey the data that may be 

 competent to indicate the existence and configuration of Precambrian 

 continents. 



Survey of Views on Origin and Age of Continents and Oceans 



Our forefathers in geology assumed that the earth, upon emerging 

 from its molten stage, was a fairly regular geoid with but unim- 

 portant prominences, except the equatorial bulge due to the rotation 

 of the earth, and that it was evenly covered by a vast primordial 

 ocean. This ocean had entirely come out of the atmosphere and 

 it was one of the terrible geologic possibilities that were presented 

 to us in the days of our youth, that this ocean might all be used up 

 in the hydration of the earth crust. 



In contrast to these early views, some of the foremost geologists 

 of the present age consider the continents as original and persistent 

 features of the face of the earth. Dana was probably the first to 

 clearly proclaim the constancy of the continents and oceans. According 

 to his view (see Barrell, 1919, p. 282), the major relief of continent 

 and ocean floor was obtained in the original freezing of a crust 

 and consequent upon the faster cooling and shrinkage of certain 

 portions. It was Dana who conceived the idea of the North Ameri- 

 can continent growing from an Azoic nucleus, the Laurentian shield 

 of later authors, flanked by a deeper channel on either side. Osmond 

 Fisher assumed that the fundamental features of the face of the 

 earth are primarily due to the rotation of the earth ; the latter having 

 rotated so fast in primordial times that a part of the siliceous crust, 

 that of the Pacific hemisphere, was thrown off and formed the moon. 

 Portions (America and Australia) of the remaining siliceous crust 

 floated away and drifted toward the great Pacific depression, and 

 thus divided the original siliceous crust into continental masses 

 separated by oceanic basins. The untenability of this view has 

 been asserted by Barrell. Suess, in his Antlitz der Erde has elabo- 

 rately worked out the hypothesis of the gradual formation of the 

 ocean basins at the expense of (originally all embracing) continents 



1 A preliminary note, entitled "On Some Fundamentals of Precambrian 

 Paleogeography," has been published by the writer in the Proceedings of the 

 National Academy of Sciences, 19 19, 5:1-6. 



