28 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



the areas east and west of Puerto Plata the mountains lie back from the 

 shore, and the area between them and the sea is hilly or rolling. 



The upland west of Puerto Plata and north of Bajabonico consists of 

 rather evenly sloping ridges whose summits reach altitudes of about 250 

 meters. Above these summits rise sharp little peaks composed of steeply 

 dipping bedded rock. The surface represented by the summits of these 

 ridges appears to extend around the south, the east, and the west sides of 

 Monte Isabel de Torres, but the details of its features and their significance 

 cannot be ascertained without careful study aided by adequate topographic 

 maps. A low coastal apron extends around Puerto Plata and an alluvial 

 flat along Rio San Marcos. Alluvial or detrital benches appear to reach as 

 high as about 60 meters above sea level, but during the very hasty examina- 

 tion of Rio San Marcos valley no definite system of terraces could be recog- 

 nized. 



SAMANA PENINSULA. 



Samana Peninsula consists of a mass of fairly rugged but not very high 

 mountains and at some places of a fringe of flat to rolling lowlands. It 

 projects about 50 kilometers eastward from the northeast corner of the main 

 island mass. Its average width from north to south is 11 or 12 kilometers. 

 The west end of the peninsula is separated from the Cordillera Septen- 

 trional on the mainland by a flat, swampy area, the Gran Estero, which in 

 the not very remote past was an open strait, but which has now become 

 nearly closed, partly by uplift of the land and partly by filling in by silt 

 brought down by the Rio Yuna. Water connection between Samana Bay 

 and the Atlantic Ocean through the Gran Estero is said to be still main- 

 tained by several distributaries of the Yuna. 



The main mountain mass is divided into three parallel ridges. On the 

 north coast, the mountains come down close to the sea but are interrupted 

 by several stretches of broad, sandy beach. The southern ridge rises 

 steeply from the water between Punta Balandra, at the southeastern ex- 

 tremity of the peninsula, and Los Cocos (see PL III, B), but west of Los 

 Cocos it is bordered by a narrow fringe of rolling land, probably the dis- 

 sected remnants of a series of terraces, which range in altitude from sea 

 level to about 30 meters above it. (See PL III, C.) The mountains in the 

 central part of the peninsula rise to about 500 meters above sea level, and a 

 few are probably somewhat higher. Among the more prominent peaks 

 whose altitudes are shown on the charts of the Hydrographic Office of the 

 United States Navy are El Pilon de Aziicar (Sugar-loaf), 491 meters, 

 6 or 8 kilometers inland from Santa Barbara de Samana; a neighboring 

 peak, perhaps Monte la Mesa (Table Mountain), 558 meters; Monte 

 Diablo, rising from the water at Punta Balandra to a height of 400 meters; 

 and Loma Las Cafiitas, at Sanchez, the highest point of which is said to be 

 514 meters above sea level. 



