SUMMARY 647 



This emergent phase continued throughout nearly the whole of the 

 Eocene, for while there was a local transgression from the East, repre- 

 sented by the San Jorge formation in Patagonia, this was not of sufficient 

 magnitude to connect the waters of the Atlantic and the Pacific. There 

 was thus afforded an opportunity for the flora of North America to in- 

 vade South America at the beginning and toward the close of the Upper 

 Cretaceous, already indicated by the presence of representatives of the 

 Dakota sandstone flora in Argentina,-" and similar land connections were 

 available throughout most of Eocene time. Similar opportunities for the 

 interchange of terrestrial life, both animal and vegetable, between South 

 America and Antarctica were also present during these same intervals. 



During the Oligocene there is evidence of minor transgressions in 

 Panama; on the Peruvian coast, where the Ovibio stage contains two or 

 three marine forms but is mainly a littoral and continental flysch-like 

 sandstone ; in Patagonia, where the Magellanian beds contain oyster beds 

 and a few other shallow-water marine forms between two lignitic hori- 

 zons. This Oligocene emergence is marked in Chile and Graham Land, 

 and by the continental Deseado formation (Notostylops, Pyrotherium 

 beds) of Patagonia. 



Toward the end of Oligocene time or the beginning of Lower Miocene 

 (Aquitanian-Burdigalian stages) we everywhere find evidence of marked 

 submergence. This is shown by the Culebra, Emperador (continental), 

 and Gatun formations of Panama; by the Zorritos and Heath stages of 

 Peru, and by the Navidad beds of southern Chile. The faunas of these 

 west coast beds are remarkable for the Caribbean and Mediterranean 

 elements that they have furnished, thus affording collateral evidence of 

 the free mingling of the waters of the Atlantic and the Pacific where the 

 Isthmus of Panama now stands. Similar evidence of submergence is 

 furnished by the marine Patagonian beds, whose fauna has been described 

 by Ortmann, and possibly by a part of the younger Seymour Island beds 

 of Andersson. 



The upper Miocene is, so far as I know, a time of rather widespread 

 emergence and land connections. No marine upper Miocene is known 

 from Panama, Chile, Patagonia (continental Santa Cruz beds), or Ant- 

 arctica. The Talara stage of Grzybowski in northern Peru is the only 

 exception to this statement, and if it is coiTcctly correlated it represents 

 a very minor movement of the strand. 



Following the widespread upper Miocene emorgenco, there is an equally 

 widespread Pliocene submergence, illustrated by the Toro limestone of 



20 K. Kurtz: Sobrc la existencia dc una Dakota-Flora on la Patagonia austro-occidontal 

 Revista Museo de La I'lata. vol. 10, 1899, pp. 43-GO. 



