74 NEW YORK STATE MUSEUM 



the bordering zones between the more stable continental and the 

 unstable oceanic areas. 1 



As this admittedly very imperfect survey of the opinions held by 

 competent authors on the permanence of the oceans and continents 

 shows, there still exist wide differences between their views, which 

 become still more apparent when the causes are sought out (see 

 postea) which they assign to the fundamental changes in the sur- 

 face of the earth. While this is not an occasion for entering 

 on a general discussion of the problems of the constancy of continents 

 and oceans beyond pointing out the lack of uniformity of opinion 

 regarding them, it is yet to be emphasized that the problem of the 

 Precambrian continents which it is intended to discuss here, bas an 

 important bearing on the larger question of the general permanency 

 of the continents and oceans. 



It is the writer's belief, that fairly direct evidence of the existence 

 and configuration of the Precambrian continents can be derived 

 from the geologic data at hand and that this evidence suggests that 

 the continental masses of the present day are recognizable in Pre- 

 cambrian time and further that these early continents occupied 

 much larger areas than their recent descendants. 



Our evidence is taken from the following groups of geologic facts: 

 (i) the Precambrian fold systems, (2) the Postcambrian fold systems, 

 (3) the configuration of the Cambrian continents, (4) the character 

 of the Precambrian deposits. 



Actuality of Precambrian Folding and Fold Systems 



Prof. W. M. Davis has lately in a review of Suess's " Face of the 

 Earth" pointed out that "wisely directed attention might be given 

 to the ancient deformations of the long afterwards undisturbed 

 regions, like Laurentia, Angara and Gondwana; and coordinated 

 effort might thus be made to extend the beginnings already outlined 



1 It likewise appears that European authors (see Th. Arldt, Die Verbindung 

 Madagascars mit Africa in der geologischen Vorzeit, in Geol. Rundschau, 10:63 ff. 

 1919; Gerth, H. Die Fortschritte der geologischen Forschung in Argentinien und 

 einigen Nachbarstaaten wahrend des Weltkrieges. ibid. 1921, 12:74 ff-» an d 

 especially E. Jaworski, Das Alter des sud-atlantischen Beckens, ibid., 12 : 60, 1921) 

 are not inclined to accept the permanence of the south Atlantic. Also the 

 Argentine geologists, under the leadership of H. Keidel (Ueber das Alter, die 

 Verbreitung und die gegenseitigen Beziehungen der verschiedenen tektonis- 

 chen Strukturen in den argentinischen Gebirgen; Compt. Rxend. 12 Int. Cong. 

 I 9 I 3. P- 671-88; and La Geologia de las Sierras de la Provincia de Buenos Aires 

 y sus relaciones con las montafias de Sud Africa y los Andes; in An. de Min. 

 de Agric. de la Rep. Argent. Secc. Geol.; Min. y Mineria, v. 9 no. 3, 191 6) prefer 

 to support Clarke's inference that the peculiar character of the Antarctic Devonian 

 can be explained only by the assumption of a large south Atlantic continental 

 mass, separating the Antarctic Devonian sea from the Mediterranean sea. 



