MUSEUM OF COMPARATIVE ZOOLOGY. 267 



now seen at Baracoa, where the surf line, which enters the narrow bay 

 with gathered force, breaks against the unconsolidated miocene yellow 

 deposit constituting the sides of the harbor back of the elevated reef, 

 and huge blocks of the latter constantly topple over into the bay. 



There is general remark throucrhout Cuba that the harbors are becom- 

 ing shallower. Captain Mclntyre, a trustworthy mariner, who has been 

 trading at Baracoa for over forty years, assured me that within his 

 memory the anchorage area has steadily decreased, and that ships which 

 formerly discharged their cargoes at a pier, are now dependent upon 

 lighters. While it is very probable that the silt from the rivers is a 

 partial cause of this, it may be probable that steady elevation now going 

 on, as it has certainly gone on in very recent time, may be productive of 

 the shallowing. 



The ovoid harbors thus developed from the simple type of river 

 emptying directly into the sea and undermining the contiguous reefs 

 attain a third stage (Plate II. Figs. 7 and 4) in which the regular margins 

 become denticulated and irregularly indented by erosion, as seen in the 

 harbors of Havana and Escondido. In the harbor of Havana the ex- 

 cessive irregularity of the interior margin is increased by the fact that 

 the limestone background has been cut through down to the tuffs, 

 serpentines, and clays underlying it, which degrade into more irregular 

 topography than that of the limestones. 



Terraces • and Benches. 



The most striking feature in the topography of Cuba consists of the 

 well defined terraces and benches which mark its jcoasts in many places. 

 These are often so distinct, especially at the east end of the island, that 

 their continuity is traceable for many miles, as they rise abruptly from 

 the water's level, one above the other, in a series of cliffs. On the west 

 end of the island they are not so distinctly visible from any single point 

 of view, for the flat benches are much wider, but they are nevertheless 

 traceable. In other places denudation has destroyed them. 



Besides these benches and terraces, whose integritv is distinctly pre- 

 served, remnants of older and more denuded levels can be traced, and 

 for convenience they may be classified as follows : — 



4. The Sobornco, or elevated reef level, j 



3. Elevated beach and cliff lines and ? 1. Later (Lower) levels, 

 the Havana base levels. ' 



2. The Cnrhilla level. 

 1. Tlie Yuiiiiue level. 



\ 2. Older (Higher) levels. 



