10 



FOREST CONDITIONS OF PORTO RICO. 



limestone hills, the remnants of a dissected cuesta or sloping plateau. 

 The interior hills of this group, which are most pointed, rise to 1,200 

 feet above sea level, although they stand only 300 to 500 feet above 

 the intervening valleys. The extent of this country north of Lares 

 and San Sebastian the writer was unable to determine from personal 

 study, but it apparently stretched below to the northern seacoast. 



THE STREAMS. 



Through the mountainous mass numerous and copious streams ramify 

 in every direction. (See fig. 2.) 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 How to the west, while the streams of the south 

 and east sides, although copious, are comparatively short. The upper 



Fig. 2.— Mountain stream, Sierra Luquillo. 



ramifications of the three principal rivers of the north coast reach 

 southward nearly across the island. The most eastern of these is the 

 Loiza, which rises only 8 miles north of Arroyo, on the south coast; the 

 Eio de la Plata, which rises the same distance north of G-uayama, and 

 reaches the north coast near the central meridian of the island: the 

 Eio Grande, which rises 12 miles north of Ponce, near Adjuntas, and 

 empties into the sea near Arecibo. 



Besides the wide alluvial plains near the mouths of the streams, to 

 be described later, the lower stretches of these northern streams pre- 

 sent considerable areas of bottom land, extending for some distances 

 within the margin of the mountain area, rarely broadening out into 

 local circular mountain valleys. Their upper portions are steep angu- 

 lar gorges, however, where habitations are confined to the slopes and 

 not the valleys. There are other streams of the island which also pre- 

 sent small areas of bottom land, indenting the mountainous area for a 



