258 BULLETIN OF THE 



Flat, marshy alluvial deposits (cienagas) occur in many places, but 

 mostly on the south coast. At Batabanos, opposite Havana, the coast 

 for a mile or more inland is composed of ancient alluvial material, ap- 

 parently similar to a calcareous mud now depositing and forming the 

 bottom of the adjacent sea for a mile out from laud. These cienagas 

 and cienaga deposits are reported to have considerable extent at various 

 places, especially on the south coast. The elevated portion is synchronous 

 with the soboruco elevation on the north coast. 



A striking' peculiarity both of the older structures and the coast 

 deposits of Cuba is the scarcity — almost total absence — of arenaceous 

 or sandy deposits. Nowhere is found the fine quartz sand such as 

 accumulates arovuid the northern littoral of the Gulf of Mexico, and the 

 presence of pieces of quartz gravel is very rare, even in the delta deposits. 

 This is owing to two reasons : (1) the formations of the island, both the 

 older metamorphic foundation and the limestones, possess Yevy little free 

 quartz, and (2) the littoral sands or physical sediments of the peripheral 

 drainage of the Gulf, derived from the continental Americas, are not 

 transported as far as Cuba, as Professor A. Agassiz has alread}' pointed 

 out. Even the building sand of Havana and other places is calcareous 

 beach debris. 



Beefs. — No description of the geology of Cuba would be complete 

 which stopped at the ocean level, without allusion to the adjacent sub- 

 merged coral reefs that fringe its shores or lie a short distance away, 

 which, with the adjacent submarine topography, have been so ably 

 described by Mr. Agassiz.^ So fully has he described these phenomena 

 that it is not necessary to discuss them further, except to call atten- 

 tion to the fact that there are often considerable deptlis between the 

 barrier reefs and the near-V)y land. This has important bearing upon 

 the topography of parts of the coast. 



II. GEOLOGIC HISTORY RECORDED BY THE 



TOPOGRAPHY. 



General Topograph^/. — Having reviewed the fundamental rock struc- 

 ture upon which the sculpture of the land is dependent, we can now pass 

 to a more intelligible discussion of the general topography and its evo- 

 lution. It is neither necessary nor possible to give a minute detailed 

 description of the geography of Cuba, but only so much as may relate 



1 Bull. Mus. Conip. Zool., Vol. XXVI. No. 1, December, 1894. 



