History of the Island of Cuba. 203 



which may have been either coral sand, or the yellow Miocene 

 clays. It was impossible to get ashore or to examine them, 

 although it was the only locality seen by me where there was 

 a suspicion of an eolian formation. The greatest areal devel- 

 opment of the flat Seboruco was found along the outlet to this 

 harbor. It is found from Cape San Antonio to Cape Mayci 

 on the north side of the island, and on the south side at many 

 places especially at Guanabaco and Santiago, as described by 

 Kimball. 



Nowhere have I seen the elevated reef rock folded or other- 

 wise disturbed except by the gently sloping coastward inclined 

 elevation it has undergone. The interior margin I have never 

 observed at a height of over forty or fifty feet. In general 

 there is only one massive layer of this old reef rock exposed, 

 but at Matanzas there is undoubted evidence of two older 

 underlying reefs, the inner edges of which have been elevated 

 with the modern reef so that they do not form distinct terraces. 

 It may be that the almost continuous elevated reef around 

 Cuba represents more than one of these layers. Whether one, 

 or several alternations of reefs, the Seboruco as a whole cer- 

 tainly represents a recent and uniform elevation of the whole 

 periphery of the island, at a very recent period of geologic 

 time, but sufficiently long ago to permit of considerable altera- 

 tion and erosion. 



Cienegas. — Flat marshy alluvial deposits occur in many 

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

 the coast for a mile or more inland is composed of ancient 

 alluvial material apparently similar to a calcareous mud 

 now depositing and forming the bottom of the adjacent sea 

 for a mile out from land. These cienegas and cienega deposits 

 are reported to have considerable extent at various places. 

 The elevated portion is synchronous with the Seboruco eleva- 

 tion 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 fine quartz 

 sand found, such as accumulates around the northern border of 

 the Gulf of Mexico, and the presence of pieces of quartz 

 gravel in even the delta deposits is rare. This is owing to two 

 reasons. (1) The formations of the Island — both the older 

 metamorphic foundation and the limestones contain very little 

 free quartz, and, (2) The littoral sands or sediments of the 

 peripheral drainage of the Gulf are not transported as far 

 south as Cuba, as already pointed out by Prof. Alexander 

 Agassiz. Even the building sand of Havana and elsewhere is 

 calcareous beach debris. 



