Il8 NEW YORK STATE MUSEUM 



these authors agree according to their maps in the assumption 

 of a former greater extent of the continent in early Cambrian time. 

 Schuchert states (ibid., p. 517) that " from the extent and position 

 of the Lower Georgic invasions, it is inferred that the North American 

 continent was larger during the late Proterozoic than at any sub- 

 sequent period." There is no doubt that North America extended 

 not only considerably .to the east of the Atlantic states in 

 " Appalachia " but also in Arcadia, and especially in the far north- 

 east, where it reached over Greenland to Europe. Holtedahl's map 

 extends the Lower Cambrian continent over Iceland around Scotland 

 to southern Norway. In the west the continent also reached beyond 

 the boundaries of the present continental mass, as is evidenced 

 by the absence of massive Cambrian deposits in the coastal regions. 



In his " Paleogeography of North America " Schuchert has 

 repeatedly pointed out that the Precambrian era closed with a great 

 continental elevation. He states (ibid., p. 482), " Laurentide 

 revolution.- — This was one of the 'critical periods' of the earth 

 when the seas were withdrawn from North America for a very long 

 time. During this interval, of which only the later or eroding 

 portion is known, the continent was larger than at present, possibly 

 as great as at the close of the Paleozoic, or even greater than at 

 that time." 



In its general form, its northeast extension across the northern 

 Atlantic and its eastward extension into the Atlantic, this early 

 Cambrian continent fully agrees with the Precambrian continent 

 inferred by us from the trend lines of the Precambrian folding and 

 foliation. It was therefore already in Cambrian time a continental 

 mass of long existence; dating back even into Archeozoic time 

 according to the evidence from the Archean folds. 



As a perusal of Ulrich's and Schuchert' s authoritative charts will 

 readily show, this continent has in its main body persisted through 

 all later time as a distinct entity. It has been invaded by epicontinen- 

 tal seas from various directions, principally the four cardinal directions, 

 but has frequently again emerged. The one great exception is the 

 large continental extension to northern Europe across the north 

 Atlantic. This mass of continental size existed as an undoubted 

 land mass until Devonian time, where as the " Eria " of some 

 paleogeographers and the " Atlantis " of others (see fig. 1), it com- 

 prised even the greater part of Great Britain, Scandinavia and 

 northern Russia. The Atlantic was then restricted to the 

 " Poseidon " of Schuchert whose northern boundary extended straight 

 across from Labrador to middle Ireland. In more restricted form 



