STRATIGRAPHIC PALEONTOLOGY. 95 



the Priabona formation of northern Italy. It appears that there are no 

 Paleocene nor lower and middle Eocene sediments above sea level in the 

 West Indies. Upper Cretaceous deposition was terminated by intense 

 deformation and by the emergence of the sea bottom above sea level, 

 where it stood for a long time. The unconformity between the Upper 

 Cretaceous and the overlying Tertiary deposits is great wherever it has 

 been actually studied — in fact, it is the greatest unconformity known in 

 that part of the world. 



OLIGOCENE. 



Most of the Oligocene deposits of the Dominican Republic are of middle 

 Oligocene age. They occur on both the north and the south side of the 

 Cordillera Central and in the Sierra Septentrional. The deposits in the 

 different districts that are sufficiently fossiliferous to warrant the expression 

 of an opinion regarding their age seem to be stratigraphically equivalent 

 and to be of about the same age as the Antigua formation of Antigua. 

 Equivalent deposits also occur in Saint Croix, where Vaughan collected 

 Lepidocyclina morgani Lem. and R. Douv., Carpenteria americana Cush- 

 man, Astrocoenia decaturensis Vaughan, Goniastrea reussi (Duncan), 

 Cyathomorpha tenuis (Duncan), Diploastrea crassolamellata (Duncan), and 

 Goniopora microscopica (Duncan). Deposits of middle Oligocene age are 

 found also in Porto Rico, Cuba, southwestern Georgia, eastern Mexico, and 

 Panama, and probably in Trinidad. The European equivalent of this 

 horizon seems to be the Rupelian Oligocene. 



The recognition of middle Oligocene in the Dominican Republic is based 

 primarily upon Foraminifera and corals. The molluscan fauna can not be 

 confused with the later faunas, and it indicates that the middle Oligocene 

 Mollusca of the Dominican Republic form a local faunule that bears little 

 relation to the known faunules of similar age in other West Indian islands. 

 Two small faunules from Rio Yaque del Sur near Los Bancos (stations 8565 

 and 8619) are apparently of middle Oligocene age. The determination of 

 these two faunules as middle Oligocene is based not so much on their 

 similarity to known middle Oligocene faunules as on their dissimilarity to 

 the Miocene faunules collected on the south side. The small collection 

 of plants from station 8564 is of middle Oligocene age if the age of the 

 Mollusca from station 8565 has been correctly determined. Until now 

 no lower Oligocene marine sediments have been certainly recognized in the 

 West Indies, perhaps because of emergence above sea level or because some 

 of the sediments now classified as middle Oligocene should be referred to the 

 lower Oligocene; or lower Oligocene deposits may be there but have not 

 yet been found. The Tabera formation, according to Cooke (p. 61, this 

 volume), is thick, and the middle Oligocene fossils were found in its upper 

 part. Its lower part may be lower Oligocene. On the south side of the 

 Republic a period of erosion appears to have intervened between Eocene 

 and Oligocene deposition. 



