hill: geology of Jamaica. 187 



feet above its level — in fact not over fifty — although tlie whole of tlie 

 white limestones of that island rising to heights of 2,000 feet or over, 

 have been erroneously attributed to coralline origin by various writers,^ 



Similar low elevated reefs occur completely around the island of 

 Haiti, as described by Gabb in a manuscript in the library of the 

 United States Geological Survey, which recounts the results of a 

 second visit to the island after his large report on San Domingo had 

 been published, in which he had erroneously attributed all the white 

 limestones of the region to coral reef origin. The writer has seen many 

 of these reefs on the coast of San Domingo, and they are in general 

 analogous to those of Cuba and Jamaica, although the three subsiding 

 stages of the latter island have not been differentiated. Concerning 

 Porto Rico and the Virgin Islands we have no data proving the exist- 

 ence or non-existence of elevated reefs around their borders. According 

 to Cleve's description of the Virgin Islands,^ and my observations of 

 Barbuda, the geological position of the elevated reefs of the Great 

 Antilles is generally occupied in these islands by the granular white 

 limestone with molluscan remains previously described. Sombrero, 

 as described by Julien,^ however, is an exceptional locality in this 

 general region, as it is composed of elevated reef rock, the Bulla lime- 

 stones and lagoonal material. There is some evidence in the reports 

 of McClure ^ and Henry ^ that elevated reefs occur on the island of 

 St. Croix. 



The elevated reef phenomena of the Lesser Antilles are varied and 

 peculiar, presenting different aspects in Barbados and on the leeward 

 and windward sides of the Caribbee Islands. On the windward side 

 of the Caribbees true elevated reefs of the modern type are found bor- 

 dering Desirade, Marie Galante, and Grand Terre-Guadeloupe, as noticed 

 by Maclure in 1817.^ Here they occur as in the Western Antilles as 

 simple undeformed benches of reef rock standing from six to ten feet 

 above the level of the sea. The reefs of Guadeloupe were described by 

 Duchaissang in 1847,^ and were considered by him to be recent in age, 

 and synchronous with the upland formations of that island which con- 

 tain the remains of fossil man. 



1 Gabb, Crosby, and otiiers. 2 Cleve, he. cit., p. 18. 



3 On the Geology of the Key of Sombrero, W. L, Annals of Lyceum of Nat. 

 Hist, of N. Y., Vol. VII. pp. 251-278. 



4 Trans. Phila. Acad. Nat. Sci., 1817, Vol. I. p. 138. 



6 Amer. Journ. Sci., 1839, Vol. XXXV. p. 73. 



, « Jour. Phila. Acad. Nat. Sci., 1817, Vol. I. p. 135. 



7 Bull. Soc. Geol. de France, 2d Series, 1842, Vol. IV. Pt. 2, pp. 1093, 1094. 



