60 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



lumps of limestone breccia were found. The limestone hills are probably 

 fault blocks in which the tilting did not produce folds in the limestone. 

 The dip of the limestone, were there no fault, would carry the rock beneath 

 sericite schists of the basal complex. The limestone is more thinly bedded 

 than at the caves in Sierra Prieta but in other respects closely resembles it. 

 Associated with the limestone on a hill west of Hatillo are many loose blocks 

 of magnetite, the source of which has not been discovered. This is the 

 celebrated "Iron Mountain," described in glowing terms by Gabb, 1 but 

 there is evidently no large deposit of magnetite at this locality. Further 

 remarks on the iron deposits of this region will be found in a paper by 

 R. B. Brinsmade 2 and in the report on mineral deposits near Hatillo and 

 Maimon on pages 228-231 of this volume. 



Paleontologic evidence of the age of the limestone in Sierra Prieta and 

 at Hatillo is lacking. The only organisms that were obtained from the 

 rock are massive forms, which appear to be calcareous algae, and these have 

 not yet been critically studied. This limestone is supposed to be of Eocene 

 age because it resembles other Eocene rocks, but it may be older. 



Specimens of limestone collected by Mr. Condit from the seashore about 

 8 kilometers south of Barahona (station 8576) contain Foraminifera that 

 are regarded by Doctor Cushman as "very definitely upper Eocene." 

 The same species are found in the upper Eocene of Cuba. Mr. Ross found 

 limestone containing Foraminifera similar to those in the Plaisance lime- 

 stone of Haiti on the southwest slope of Canada de Rancho Viejo, in the 

 Sierra de Bahoruco, south of Rancho Viejo (station 8627), and pebbles of 

 similar limestone occur also in Oligocene or Miocene conglomerate in the 

 vicinity of Rancho Viejo (station 8626). 



Rubble containing the Foraminifera listed on page 106 (station 8595) 

 was found by Mr. Condit in the Sierra de Neiba about 2.5 kilometers 

 north of Barbacoa. 



Rocks of Eocene age were identified at several localities in the Province 

 of Azua. These are discussed on pages 199-200, and lists of the iden- 

 tifiable fossils found in them are given on page 106. 



Along Rio Via above Azua there is massive limestone conglomerate, 

 probably not over 50 feet thick, containing pebbles of greenish rock. 

 Apparently above the conglomerate there is a thicker series of massive 

 blue-gray limestone and alternating thin beds of limestone and shale, fol- 

 lowed, near the top, by a few beds of limestone and shale. This entire 

 formation except the limestone conglomerate is very much sheared and cut 

 by small overthrust faults. A larger fault causes repetition of the greater 

 part of the formation, including the conglomerate. The strike of the forma- 



' Gabb, W. M., On the topography and geology of Santo Domingo: Am Philos. Soc. Trans., vol. 

 15, n. s., pp. 141-142, 1873. 

 1 Brinsmade, R. B., Iron in Santo Domingo: Min. and Sci. Press, vol. 117, pp. 356-358, 1918. 



