X93 



Costa Rica Miocene— Olsson 



21 



stratigraphic unit, and Oabb insisted that no division was possi- 

 ble. Dr. Maury however, as a result of paleontologic studies 

 from collections carefully made in the field, was able to divide 

 the Dominican Miocene into two formations, which she called 

 the Gurabo and the Cercado. To these Vaughan and his as- 

 sociates, in more recent stratigraphic work on the island, have 

 added 4 other subdivisions. The present recognized subdivisions 

 of the Dominican Miocene are; 



MIDDLE 



LOWER 



Mao clay 



Mao Adentro limestone 



Gurabo formation 



(^Sconsia laevigata zone) 



Cercado formation 



(^Aphera islacolonis zone) 



Baitoa formation and Bulla 



conglomerate 



The relation of the Costa Rican and Panama Miocene to 

 that of Santo Domingo is extremely close; there being about 

 90 species in common. Of this number about 21 are recent, 

 about 26 species appear to be restricted to the Gurabo, some 27 

 species are common to both the Gurabo and Cercado formations, 

 and only 1 1 species are confined to the Cercado. The list of 

 of Costa Rican and Panama species in the Dominican Miocene, 

 is as follows: 



Nucida te7iuisculpta Gabb 



'^Arca occidentalis Phil 



'^Arca timbo7iata I^amarck 



Area Maury ce Olsson 



Area Henekeni Maury 



Area golfoyaquensis Maury 



Area chiriquiensis Gabb 



'^'■Arca auriculata lyamarck 



Cercado and Gurabo 

 Cercado and Gurabo 

 Cercado 

 Gurabo 

 Cercado 



Cercado and Gurabo 

 Gurabo 

 Gurabo 



*Recent 



