170 



on THE TOPOGKAPHY AND GEOLOGY 



stone aiici the fine-grained silver gray mica slate of Corozal, which is doubtless derived 

 from the same formation. 



The coast liffiestotie of Puerto Plata extends eastward along* the sea, nowhere, 

 however, so important a formation as it becomes on the south side of the Island. 

 Instead of forming a great rocky blutf hiding everything imder it, it modestly skirts 

 Httle patches, sometimes barely shows itself through the sand of the beach, or is 

 covered up under the high salid dunes, or again appears as broad shelving reefs 

 extending far out to sea with an almost imperceptible seawai'd dip. In some cases, 

 however, as near the little River Susua, it makes low hills of limited extent, being 

 pushed up alone with the older Tertiary that forms their bases. It also most pi'o- 

 bably unde]-lies the numerous little " l!ats and valleys which border the north side 

 of the range, and which make some of the prettiest farming sites in the country. 

 Among these may be liamed as pre-eminent Batei and Caberete. West of the latter 

 place there is a peculiar spot, different from any other I have seen on the Island. The 

 low-lying coast and the constant beating of the winds and waters of the Atlantic 

 render the north side much more liable to be covered by sands drifting u]) from the 

 beach than the south side. Sand-dunes are the exception rather than the rule where 

 the forest does not reach to the water's edge. On the other hand, the greater exuber- 

 ance of Vegetation ili this tropical region acts as a partial check to the drifting sand, 

 and the forest crawls seaward about as fast as the sand dips inland. From this 

 never-eliding struggle there results many small dunes, their windward face smooth 

 from the renewing influence of the wind, while the leaward side is almost always 

 covered with brush, whose growth keeps pace with the growth of the hill, and by 

 opposing a wall to the wind, eddies back a large part of the sand that would other- 

 wise creep inland. But at the Palmal tens of thousands of the Oanna palm, young, 

 form a grove of two or three miles in extent, with but little undergrowth except 

 trees of the same species, their roots firmly knit into the crevices of the under- 

 lying limestone, and the soil a shifting layer of lieach sand which drifts into the 

 grove, but with the force of the wind so broken by the innumerable tree trunks that 

 it is spread out evenly instead of being piled uj) in the familiar ridges. The sand is 

 as loose and shifting as a dry beach, and so barren that hardly a blade of grass or a 

 bush can find nourishment in it ; but the palms thrive admirably. 



The next opportunity for the study of the range that exists east of the Palo Qne- 

 mado route, is the road from Moca, by way of Jamao to Batei. This pass ascends 

 the side of a carton in which the dark gray shales and beds of sandstone of the lower 

 part of the shale series dip fii'st as high as 50° north. Great exposui-es, some of them 



