200 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



Province of Barahona, as follows: Station 8626, limestone pebbles near 

 RanchoViejo; station 8627, foraminiferal limestone, Sierra de Bahoruco, 

 west slope of Canada de Rancho Viejo; station 8576, foraminiferal limestone 

 from near sea beach, south side of Rio Cana, about 9 kilometers south of 

 Barahona; station 8595, rubble on mountain slope 2.5 kilometers north of 

 Barbacoa. The fossils obtained at these localities are listed on page 106. 

 Sediments of probably Eocene age were seen at other places. 



The mountain ridges of dense gray limestone in the southwestern part 

 of the Dominican Republic are at least in large part composed of rocks of 

 Eocene age. In the Republic of Haiti similar rock containing Eocene 

 fossils forms the limestone mountains. Vaughan collected specimens of 

 limestone containing Eocene Foraminifera at Cape Haitien and around 

 Plaisance. The mountains around Ennery, between Ennery and Go- 

 naives and between Gonaives and the Cul-de-Sac are composed largely of 

 Eocene limestone, according to Vaughan. 2 W. F. Jones estimates that 

 the limestones near Port-au-Prince attain a thickness of at least 8,000 

 feet, but he did not distinguish between Eocene and Oligocene deposits. 3 



Oligocene. 



Oligocene fossils were found at five localities in the Province of Azua, 

 as follows: Station 8617, Las Cuevas, Rio San Juan, north of San Juan; 

 station 8618, limestone hill at Majagual, Rio San Juan, north of San Juan; 

 station 8565, Rio San Juan, about 1.8 kilometers west of Los Bancos, upper 

 part of exposure; station 8619, Rio Yaque del Sur, near Los Bancos; 

 station 8567, limestone, right bank of Rio de las Cuevas, about 1.9 kilome- 

 ters west of Tubano. For lists of fossils from these localities see page 109. 



The stratigraphic relations of the Oligocene to the Eocene deposits 

 were not definitely ascertained, but the exposures along Rio San Juan 

 about 1.8 kilometers west of Los Bancos strongly suggest that the rocks 

 belonging to the two series are separated by an unconformity. The strata 

 at station 8565 are exposed in a bluff about 900 meters long on the south 

 side of Rio San Juan; the dip is northeastward at an angle of 10° to 13°. 

 The material consists of fossiliferous conglomeratic shale and argillace- 

 ous sandstone. The fossils comprise coral fragments, oysters, and gastro- 

 pods. At a horizon about 100 meters stratigraphically lower pooily pre- 

 served plant remains were found in evenly bedded sandstone. Among these 

 plants Prof. E. W. Berry has recognized a species of Sophora, a coastal 

 member of the Leguminosae. The suggestion is that this area was land 

 prior to the deposition of the marine Oligocene and that the Oligocene 

 is separated by an erosion unconformity from the Eocene. Besides includ- 

 ing conglomerate, shale, and sandstone, the Oligocene deposits are in large 

 part composed of limestone. 



1 Unpublished information. 



• Jones, William F., A geologioal reconnaissance in Haiti: Jour. Geology, vol. 26, p. 733, 1918. 



