GEOGRAPHICAL DEVELOPMENT OF THE AMERICAS 123 



manner in which Europe was broken and intersected by arms 

 and gulfs of the warm southern sea. In the latter half of the 

 epoch, however, the climate became colder, the subtropical 

 flora giving way to a distinctly temperate one. 



South America. — In Central America, where marine Oli- 

 gocene beds are of great extent, no Miocene is known, and on 

 the Isthmus Oligocene is the latest marine formation, except 

 a narrow fringe of Pleistocene on the Caribbean coast. These 

 facts and others already cited lead to the conclusion that in 

 the Miocene the connection of the Americas was complete and 

 that the Isthmus was considerably broader than at present, 

 extending nearly to Jamaica. The condition of the Greater 

 Antilles is but vaguely understood, but they were involved in 

 the general elevation of the Caribbean region and were at 

 least as large as they are now and may have been considerably 

 larger, and Cuba was perhaps joined to Central America, as 

 Hayti probably was. 



In South America proper nearly the whole of Patagonia 

 was submerged by the transgression of a shallow, epiconti- 

 nental sea, in which were accumulated the beds of the Pata- 

 gonian stage, containing an exceedingly rich and varied as- 

 semblage of marine fossils, an assemblage which has very little 

 in common with the contemporary formations of the northern 

 hemisphere. It is this lack of elements common to the northern 

 faunas which has led to the long debate concerning the geo- 

 logical date of the Patagonian formation, the South American 

 geologists very generally referring it to the Eocene. How- 

 ever, the occurrence of genera of Cetaceans (whales and dol- 

 phins), which are also found in the Miocene of Maryland and 

 Virginia, is very strong evidence that the proper date of the 

 Patagonian is Miocene. A continuous coast-line, or at least 

 an unbroken continuity of shoal-water conditions, seems neces- 

 sary to account for the similarity of the Patagonian fossils 

 with those of New Zealand and Australia, and that this con- 

 nection was by way of the Antarctic continent is indicated by 



