646 E. W. BERRY CERTAIN PLANT-BEARING BEDS IN SOUTH AMERICA 



sidered as evidence of Eocene age. I would therefore dissent from 

 Wilcken's conclusions that this plant-bearing sandstone is Upper Oligo- 

 cene or Lower Miocene in age and would consider this flora as of Middle 

 or Upper Eocene age. 



Summary 



Summarizing the foregoing brief notes and going beyond them into the 

 Mesozoic in order to indicate land connections that were barriers to ma- 

 rine dispersal and avenues for the migration of terrestrial faunas and 

 floras, it may be noted that South America and i^ntarctica were con- 

 nected during the late Jurassic, and that this connection was not inter- 

 rupted during the long ages of the Lower Cretaceous. At the other end 

 of South America Panama appears to have been emerged throughout the 

 Lower Cretaceous, but there was no direct connection between Antarctica 

 and North America, unless it was over an Antillean land bridge, until 

 near the end of the Lower Cretaceous, at which time a continuous land 

 connection was established which continued with various modifications 

 throughout the Upper Cretaceous. 



During the Upper Cretaceous the world-wide Emscherian-Lower 

 Aturian transgression is recorded in the Quiriquina beds of Chile, at 

 various localities in Peru and Patagonia, and in the richly fossiliferous 

 deposits of Graham Land, with their Indo-Pacific ammonite faunas. 

 Although it was perhaps possible for these latter faunas to have invaded 

 the margins of Graham Land from the east, it seems more probable, in 

 view of the similarities of the fauna to that found in the Quiriquina beds 

 of Chile, that the land connection with Antarctica which had persisted 

 since Jurassic time was interrupted during the middle part of the Upper 

 Cretaceous, at which time shallow marine waters permitted the invasion 

 of the region by these ammonite faunas. 



Toward the close of the Upper Cretaceous, however, and throughout 

 all of southern and western South America, there is evidence that this 

 Upper Cretaceous submergence was followed by a negative movement of 

 the strand-line and emergence of the land. This occurred during the 

 time interval of the Maestrichtian and Danian stages of the Upper Cre- 

 taceous and continued for a much longer time than this throughout n^ost 

 of South America. This^late Upper Cretaceous emergence is shown by 

 the absence of any known faunas representing these stages, by the litho- 

 logic indications in the higher levels of increasing shallowness of the 

 waters, and by the continental variegated sandstones of this age in Pata- 

 gonia. At this time, then, Antarctica was connected with Patagonia and 

 tlie Isthmus of Panama was dry land. 



