TOPOGRAPHIC FEATURES. 



69 



point with an altitude of 2,500 feet, but the principal topographic relief 

 is along the southern coast of the eastern extension of the island, where 

 Pico Tarquino rises from the Sierra Maestra to an elevation of 8,400 feet. 

 The central portion of the island is generally a plain from 200 to 400 feet 

 above tide, which bears many scattered and interrupted ridges, like islands 

 in a sea. To this portion of Cuba the present study is chiefly confined. 

 The northern coast, from Havana to Matanzas, 53 miles, is high, and 

 rises out of an open sea, but both toward the east and west the low coastal 

 plains extend as submerged shelves for 10 or 20 miles farther, and are 

 surmounted by coral keys, mangrove islands and shallow lagoons. The 



Figure i.—Map of Cuba. 



same features are repeated upon the southern coast, where, however, the 

 submerged portion of the island, often covered by not more than 5 or 10 

 feet of water, forms a broad shelf, as shown on the map. There is, how- 

 ever, an exception between Cienfuegos and Trinidad, where the shelf is 

 incised by the gulf of Cazones. West of Cienfuegos the Zapata peninsula 

 is a marshy plain over a hundred miles across the front. 



Between Cienfuegos and Trinidad city there occurs the mass of Trin- 

 idad mountains, with diameters of 30 or 40 

 miles. Their altitude is 1,500 or 2,000 feet, 

 with Pico Potrerillo a few hundred feet 

 higher. From some directions the outline 

 appears somewhat regular, but from others 

 the alternating valleys and ridges produce a 

 serrated appearance (see figure 6, page 83). 

 The upper valleys are former baselevels of 

 erosion, as shown in figure 2, which have 



been disturbed by recent elevations, for the small streams are only now 

 cutting back their canyons hundreds of feet in depth. Thus the Rio 

 Caburi, a small tributary of the Rio Negra, has already excavated a can- 

 yon 600 feet deep. Only the larger streams, such as the Rio Juan, have 

 excavated deep gorges far back in the elevated valley floors of older date. 

 The Trinidad mountains form the highest reliefs in central Cuba, and 

 also the most picturesque scenery of the island. 



Figure 2.— A high baselevel Valley. 



This valley {v), more than a mile 

 wide, is being incised by the exten- 

 sion of the canyon (c) of the Rio 

 Caburi. 



