tSgg. 



AMERICAN FORESTRY ASSOCIATION. 



207 



all the Antilles the most productive, the 

 most densely settled, and the most estab- 

 lished in its customs and institutions. 

 It is also notable among the West Indian 

 group, because its preponderant popula- 

 tion is of the white race, and because it 

 produces food-stuffs almost sufficient to 

 supply its inhabitants, in addition to its 

 exports to some of the neighboring 

 islands. 



Its outline presents -the -appearance of 

 an almost geometrically regular parallel- 

 ogram, nearly three times as long as 

 broad, with its sides following the four 

 cardinal directions. The sea line is 

 nearly straight, and the coast is usually 

 low, especially on the southern side, 

 although ihere are a few headlands. It 

 is void of fringing keys and deep inden- 

 tations of its coast, such as border Cuba. 

 The coast line is 360 miles. 



Porto Rico, like all the Antilles, in 

 comparison with the United States, has 

 a configuration ancient in aspect, al- 

 though comparatively new in geologic 

 age. Of the four chief topographic 

 features of the Great Antilles (central 

 mountains, coast-border topography, in- 

 terior plains and enclosed mountain 

 basins) only the central mountains and 

 coast- border topography are represented 

 upon this island. 



The central moun'ains are largely of 

 one physiographic type. The coast bor- 

 der topography is more complex and 

 diversified, consisting of three sub- 

 types, which may be called coast hills, 

 parting valleys and playa plains. The 

 mountains constitute the major surface 

 of the island, approximately nine tenths 

 of the whole. The other features col- 

 lectively make an irregular and lower 

 lying belt around the coastal margin 

 comparable to the narrow rim of a high- 

 crowned alpine hat. 



The whole island is practically an 

 elongated elevated sierra made up mostly 

 of volcanic rock, surrounded by a narrow 

 collar or dado of limestone hills, former 

 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 with no definite crest 

 line, rising from a general mass, whose 

 steeply sloping sides are deeply corru- 

 gated by drainagewa)'s; they present the 

 aspect of a wrinkled handkerchief a 

 figure of description ascribed to Colum- 

 bus in telling Queen Isabella of the 

 Antilles. Their superfice has been 

 etched by erosion into innumerable lat- 

 eral ridges, separated by deep gorges. 



The main crest line extends from 

 Mayaguez on the west through Aibonito 

 and Adjuntas to Humacoa on the east. 

 This is called the central Cordillera west 

 of Aibonito and the Sierra de Cayey east 

 of that town. 



There are virtually two crest lines in 

 the eastern half of the island. The nor- 

 thern branch is the Sierra Luquillo^ 

 which practically extends from the west 

 of the San Juan-Ponce military road to 

 the northeast cape. This range contains 

 the highest island summit, El Yunque. 



These mountains, as a whole, when 

 looked down upon from the highest 

 points, present the aspect of a sea of 

 conical peaks and beaded ridges, rather 

 than a dividing ridge. The highest em- 

 inences of the billowy summits nowhere 

 exceed 3,500 feet, and this altitude, if at- 

 tained at all, is reached by only one peak 

 that of El Yunque, at the extreme north- 

 east. The height of this peak is given on 

 the Spanish maps at 4,087 feet, but it is 

 reported much lower by other authorities. 

 Other summits of the island, although 

 numerous, hardly anywhere exceed 3,000 

 feet. 



Through the mountainous mass nu- 

 merous and copious streams ramify in 

 every direction. These have deep valleys 

 singularly free from cliffs, and they etch 

 the surface into many lateral ridges and 

 points. Of these streams, the largest 

 and longest drain into the north coast, 

 the next largest flow to the west, while 

 the streams of the south and east sides, 

 although copious, are comparatively 

 short. The upper ramifications of the 

 three principal rivers of the north coast 

 reach southward nearly across the island. 



Besides the wide alluvial plains near 

 the mouths of the streams, to be described 



