182 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



above sea level. The altitude at Sanchez is 15 to 20 meters; immediately 

 east of Sanchez it is 10 to 15 meters. The change from the subdued 

 topography of the rolling terrane to the rugged topography of the moun- 

 tains is extremely abrupt. The mouths of all the smaller streams in this 

 area are blocked by sand bars. 



Between Los Cocos and Samana the mountains descend directly to the 

 sea. (See PI. Ill, B.) Hills 150 and 180 meters in altitude rise almost sheer 

 from the water. At Samana a narrow valley interrupts the mountains 

 and off the coast there are several small rocky islands. East of Samana 

 the hills again reach the coast. 



SOUTH SHORE OF SAMANA BAY. 



During a trip by motor boat along the south shore of Samana Bay land- 

 ings were made at a cove a short distance west of Punta de Boca del 

 Infierno, at Sabana de la Mar, and at Las Canitas. The outline of the 

 shore is shown on the United States Hydrographic Office chart No. 917. 



West of Sabana de la Mar the hills rise abruptly from the water and 

 a number of small islands lie off the coast. On both the mainland and 

 the islands sea cliffs that rise 3 to 12 meters above the water have been cut 

 in the limestone. Sea caves and horizontal channels, some of which are 

 3 meters above high tide, lead back from the cliffs. The skyline along 

 this part of the coast is remarkably even. As viewed from the bay the 

 hills seem to form a plateau which has an altitude of about 180 meters 

 above sea level. Near Sabana de la Mar the hills probably reach an alti- 

 tude of 200 meters above sea level. 



East of Sabana de la Mar the topography is decidedly different. The 

 hills are higher, are distinctly serrate, and apparently form several ranges. 

 Except at a few places, the hills descend directly to the shore, but much 

 less steeply than those to the west. 



GEOLOGY. 



The following geologic subdivisions were recognized along the north 

 shore of Samana Bay. 



Recent deposits. 



Pleistocene or Recent terraces and coral leefs. 



Miocene or Pliocene clay, sand and conglomerate. 



Oligocene or Miocene limestone. 



Eaxly Tertiary limestone conglomerate. 



Basal complex. 



BASAL COMPLEX. 



The rocks of the basal complex form the mountains of Samana Peninsula 

 and are therefore widely distributed. Metamorphic rocks were found in 

 place and pebbles of pegmatites, felsites, and other igneous rocks in younger 

 conglomerates indicate that such rocks are probably intruded into the 

 metamorphic rocks. Micaceous schist and schistose limestone are exposed 



