202 It. T. Hill — Tertiary and later 



limestones of undoubted coral reef origin which border the 

 coast in most places, or form small coral islets adjacent thereto, 

 locally known as Seboruco.* 



The elevated reef rock can always be recognized by the 

 perfection and abundance of well jDreserved remains of reef 

 making corals which form the greater proportion of the mass 

 and by the absence of lamination or bedding planes. The 

 formation averages about thirty feet in thickness, and usually 

 extends inland only a short distance, often only a few yards, as 

 on the northwest point of Moro Point, or not over an eighth 

 of a mile as at Baracoa. 



The Seboruco is a topographic as well as a stratigraphic 

 feature, for its surface which was that of the old submerged 

 reef represents a bench gently sloping to the sea ; it has 

 neither been covered by later deposits nor greatly denuded. 

 It usually forms at the surf line a cliff about fifteen feet in 

 height, against which the surf beats with great force, wearing 

 deep indentations. The spray breaking over the summit pro- 

 duces the surface induration which is visible wherever rain or 

 other moisture falls upon the hot limestones. This induration 

 at Baracoa, for instance, has converted the reef rock in spots 

 into a coarse saccharoidal marble, and aided in the segregation 

 of small bodies of iron ore directly from it. 



It is impossible here to describe all the localities where the 

 Seboruco was observed. Sometimes, as along the Havana 

 coast, it occupies a narrow strip extending from the point of 

 one harbor to another. Again as on Moro peninsula opposite 

 Havana it occurs only as a small patch in a small indentation 

 in the old headland composed of folded Miocene rocks. 



At Tanamo, and other places on the north coast the Seboruco 

 not only forms the border of the mainland, but constitutes 

 many islets bordering the same, with great areal extent. Gen- 

 erally these are low, standing only a few feet above the water. 



There is a vast elongated archipelago of these elevated reefs 

 bordering the coast all the way from a point east of Matanzas to 

 Nuevitas. In the harbor at Nuevitas there are three islands 

 known as Los Ballenatos which have great resemblance to the 

 keys of the Bahamas, presenting a bold, rounded escarpment 

 at the north point, and composed of yellow friable material, 



• * M. Ramon De La Sagra has defined this formation as follows: " L'autre 

 formation de calcaire moderne, qui a recu dans le pays le nom de seboruco, se 

 trouve le long de la cote, dans plusieurs endroits de 1'ile ; elle est tellement re- 

 eente, que son agglomeration continue meme aujourd'hui, et c'est a elle que Ton 

 doit les cayes Jes recifs et tous les bas-fonds de coraux. Les partes superieures 

 s'elevent parfois a partir d : une profondeur de vingt a trente brasses. Toutes les 

 inegalites de cette roche sont recouvertes d'une couche calcaire agglotneree avec 

 des restes d'animaux. de coquilles, de coraux et de madrepores." Histoire 

 Physique, etc. de Tile de Cuba, Tome I, p. 110. 



