62 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



At San Jose de las Matas, and extending southward from the town a dis- 

 tance of about 1.5 kilometers, Mr. Condit found steeply inclined reddish 

 conglomerate interbedded with shaly layers. The strike of the beds is 

 N. 60° W. In the south bank of Arroyo Hondo at San Jose de las Matas 

 there is an outcrop of gray semicrystalline limestone. Ferruginous con- 

 glomerate similar to that at San Jose de las Matas is exposed at a waterfall 

 on Rio Inoa about 3 kilometers farther west and not far below the mouth of 

 Arroyo Hondo. At the confluence of Rio Inoa and Rio Amina, about 3 

 kilometers below the waterfall, conglomerate and dark shaly sandstone dip 

 westward at an angle of 20° to 40°. Mingled with igneous pebbles in the 

 calcareous cement of the conglomerate are small lumps of limestone con- 

 taining corals and orbitoidal Foraminifera. Some of the Foraminifera 

 (Lepidocyclina sp.) are curved and are more than 25 millimeters in diameter. 

 They lie between the pebbles of coarse conglomerate. On the basis of 

 these Foraminifera the rock is correlated with the Tabera formation. The 

 beds of the Tabera formation in the vicinity of San Jose de las Matas abut 

 against gneissic igneous rocks to the south; to the north they are separated 

 from the sediments of the Yaque group by a strip of sericite schist, perhaps 

 1.5 or 2 kilometers wide. The presence of these conglomerates and shales 

 in the midst of the basal complex is doubtless due to faulting. 



Nearly a kilometer down the valley of Rio Gurabo from the village of 

 Gurabo are outcrops of sedimentary rocks that are believed to be, in part 

 at least, of Oligocene age. The schist here is overlain by a basal conglom- 

 erate, or rather a ferruginous breccia, made up almost entirely of fragments 

 derived from the adjacent schists. The fragments are angular and poorly 

 assorted but show distinct stratification. This deposit grades upward into 

 a fine-grained conglomerate that has a limestone matrix containing Foram- 

 inifera. A little higher stratigraphically there are beds of massive lime- 

 stone rich in corals and Foraminifera. This series of conglomerates and 

 limestones dips northeastward at an angle of about 15°. Unconformably 

 beneath these gently dipping strata are nonfossiliferous, coarse-grained, 

 bluish sandstone and dark conglomerate, which dip northwestward at a 

 steep angle. The conglomerate of the lower series appears to contain no 

 fragments from the adjacent schists. The deposits above the unconformity 

 are not greatly indurated, and lithologically the finer-grained beds resemble 

 some of those in the Tabera formation. Unfortunately the fossils col- 

 lected in the upper limestone strata were lost in transit, so that the age 

 can not be confirmed, but in the field the fossils were believed to be probably 

 Oligocene. The beds below the unconformity are probably Cretaceous or 

 Eocene. 



Besides the deposits above described and referred to the Tabera forma- 

 tion, limestone containing similar fossils was found at several places in the 

 northern part of the Republic — at El Limon, on the trail from Santiago 



