F>ROCBEDINGS 



OF THE 



CALIFORNIA ACADEMY OF SCIENCES 



Fourth Series 



Vol. VII, No. 8, pp. 197-205. July 30, 1917 



VIII 

 ANCIENT PANAMA CANALS* 



BY ROY E. DICKERSON 



Curator Department of Invertebrate Paleontology 



The fauna! relations of the Atlantic and Pacific have at 

 various times received the attention of many eminent zoologists 

 and paleontologists. Recent discoveries and investigations in 

 the Miocene, Oligocene and Eocene of the Pacific Coast and 

 Caribbean have caused the writer to review this subject again. 

 One of the principal results of this work is definite proof of 

 connections across Panama and Tehuantepec portals during 

 the Bowden stage. The Bowden stage in Florida, the Alum 

 Bluff formation, Orthaulax pugnax zone and associated zones 

 are not upper Oligocene but middle or lower Miocene. The 

 Oligocene of the Pacific Coast contains no species in common 

 with the Bowden stage and the stage of evolution of the 

 Bowden fauna is far more advanced than that of the enor- 

 mously thick strata (10,000 to 15,000 feet) of the west coast 

 Oligocene. A brief review of the geology of the Caribbean 

 and Central American areas is given below. 



A basement complex of granites and schists of unknown age 

 occurs in Mexico and Central America. In this portion of the 

 Antillean Province both upper and lower Cretaceous rocks are 

 found and there are a few scattering locations of Carbonifer- 

 ous and other Paleozoic rocks. Upper Cretaceous rocks are 



Printed from the John W. Hendrie Publication Endowment. 



July 30, 1917 



