PORTO RICO 



95 



A MOUNTAIN STHKAM, SIERRA LUQUILLO 



and Virgin islands, are largely of one general physiographic type, 

 while the coast-border topography is more complex and diversi- 

 fied, consisting of three subtypes, which may be called coast 

 hills, parting valleys, and playa plains. 



The mountains constitute the major surface of the island, ap- 

 proximately nine-tenths of the whole. The other features collect- 

 ive^ make an irregular and lower lying belt around the coastal 

 margin comparable to the narrow rim of a high-crowned alpine 

 hat. In fact, the whole island is practically an elongated elevated 

 sierra, made up mostly of volcanic rock, surrounded by a nar- 

 row collar or dado of limestone hills, formerly marginal marine 

 incrustations which have been elevated. Viewed from the sea 

 these mountains have a rugged and serrated aspect, consisting of 

 numerous peaks and summits void of a definite crest line, rising 

 from a general mass whose steeply sloping sides are deeply cor- 

 rugated by drainageways, so that they have the aspect of a 

 wrinkled handkerchief — a figure of description ascribed to Co- 

 lumbus in telling Queen Isabella of the Antilles. Their superfice 

 has been etched by erosion into innumerable gabled lateral ridges 

 (cuchillas) separated by deep V-shaped gorges. This type of 

 mountainous configuration has been described by Davis as a 

 dissected range, while the angular lateral ribs or salients are 

 known in Cuba as cuchillas (knives). 



This sculpture is so peculiar to the central mountains of the 

 island that it forms a ready means of differentiating them from 

 the foothills. The mountain region lias a long and relatively 

 gentler inclination toward the north coast and falls off more ah- 



