FIRE, ROCK, AND SEA ZV 



lions of years at a time on its northern border by the lands of 

 Scandia, Eria, and Atlantida, and on the south by a land 

 bridge or at least by a chain of islands between Africa and 

 South America, which separated the River from southern 

 Atlantic waters. 



Not all geologists agree that the Atlantic basin has existed 

 for the entire period in the way we have described it. Some 

 have suggested that up until about 200 million years ago, or 

 even later, there existed a great continent where the North 

 and South Atlantic oceans now rest. Although some of the 

 geological evidence is in favor of a more permanent Atlantic 

 Ocean, such as the one we have described, there are a number 

 of queer facts which have never been satisfactorily explained. 



When land plants and animals and fresh-water fishes are 

 separated by impassable boundaries of ocean water, without 

 land connections of any kind, they usually evolve along dis- 

 tinct lines, so that in each separate locality a different group 

 of species is found. Thus the North American fossils of the 

 later Paleozoic and early Mesozoic eras, which lived from 

 about 400 million years ago down to about 100 million years 

 B.C., are of a type distinct from those of South America. On 

 the other hand, it has been found that there are striking simi- 

 larities between the fossils of South America and those of 

 Africa, India, and the Antarctic continent. Since these could 

 not have reached South America by any other route it is 

 believed by some that there must have been a southern land 

 connection, along which fossil forms spread from the other 

 continents as they appeared in the course of evolution. Wege- 

 ner's highly controversial theory of continental drift holds 

 that a single great land mass, the super-continent of Pangea, 

 was the forerunner of all the present-day continents and that 

 it provided the necessary connection. 



It is supposed that Pangea existed until the latter part of the 

 Paleozoic, 200 million years ago, and that only then did it split 



