OF SANTO DOMINGO. 



193 



West of its month the limestones, while they continnc almost to the ISTizao, become 

 gradnally more earthy, and begin to show signs of the coast influences which acted 

 so strongly to the eastward of the months of the (southern) Yaqui, Cuevas and Ocoa. 

 The Nizao bore its part in the work, but deposited most of its debris further north, 

 to the west and even northwest of San Cristobal l^ehind the Miocene hills, then proba- 

 bly low islands, barely if at all elevated above the water. The limestone belt con- 

 seqnently is quite narrow »l3out here, and instead of being a tough rock on the 

 surface, loses the propei-ty of hardening on exposure. It gradually merges into a 

 gravel, and beyond the JS^izao towards Bani, loses all of its calcareous character. 

 In one place near the mouth of the N^igua, I found in it a bed of small oysters. 



The Miocene rocks of which Loma Christina may be taken as a type make a little 

 range of hills west of San Cristobal, extending nearly to the I^izao. Wherever I 

 have examined them, they have proven to be the same earthy, brown beds of an in- 

 termediate character between clay and limestone, alternating with beds of sandstone. 

 In the more calcareous strata corals are not rare. These are almost always of the 

 massive form, and occur abundantly as pebbles in all the streams running down 

 from the hills. The strata are a little disturbed, but the dips are, while low very 

 variable. Little ontliers of the same formation, I'emains of probably a much larger 

 deposit now denuded away, are found in the hills further Avest. I have discovered 

 rolled pebbles of Miocene corals in the Pa3''a Creek, four miles east of Bani, and Mr. 

 Speare obtained another rolled fragment of well-known form in the neighborhood of 

 Savaria Buey. Back of these hills between them and the base of the main range, the 

 Post Pliocene shingle of the ISTizao covei'S all of the lower land, large rounded pebbles 

 extending to the base of the hill just west of San Cristobal. An excellent oppor- 

 tunity of observing this, exists along the inland road from San Cristobal to Bani, by 

 way of Estancia del Rey, while the coast road shows the parallel transition westward, 

 from the limestone at Don Gregorio, near the mouth of the !N^igua through its earthy 

 stage, caused by the finer debris of the i^Tizao, to the similar shingly product of the 

 Ocoa on the plains of Bani. 



Parallel with this onter belt there is a high range of mountains, bearing several 

 peaks nearly as prominent as those of the main chain. But one of these lies east 

 of the ]N^izao River, Mt. Manaclal over 4,000 feet high. West of it are two others of 

 still greater altitude, Mts. Barbacoa and los Pinos. This mountain mass is visible at 

 a great distance, and forms an excellent landmark at sea. The first of these was 

 visited by Mr. Pennell, who reported it to be made up largely of limestone and grani- 

 toid rocks. It lies near the southern edge of the great intrusive mass, and the latter 

 A. p. S. — VOL. XV. 2w. 



