190 Geohyii of Xurtlie(isfer)i West India Islands. 



Tolcanic rocks, tufas of different kinds, iuterstratitied with beds 

 of a hard, compact limestone. There are also some massive 

 rocks, certainly eruptive, consisting of a kind of syenite-por- 

 phyry, in the southern part of the island. St. Martin, also, 

 consists mainly of stratified rocks, but not of limestone, as far 

 as I know. The stratification runs generally, both in St. Martin 

 and St. Bartholomew, from west to east, and the dip is to the 

 south about 20° — 30°. As most of the rocks are of volcanic 

 origin, we may conclude that the igneous activity continued 

 during the Eocene time. 



On the western corner of St. Martin, the Eocene sti-ata are 

 unconformably overlaid by hard white limestone, evidently a 

 fragment of the Miocene formation, Avhich forms the whole of 

 Anguilla, and there rests upon some amygdaloid volcanic rock. 



The Eocene rocks seem to occur in the southwestern part of 

 Antigua,* where they have a northerly dip ; also, in Guadeloupe, 

 Grande-Terre, they seem to occur (Pierre a Ravets de Duchas- 

 saing). In Jamaica, Eocene beds of 1,000 meters in thickness 

 occur, and consist, according to Mr. Barrett, of jDorphyritic 

 conglomerates, with shaly and sandy beds. Mr. Gabb does not 

 mention the occurrence of Eocene beds in San Domingo. They 

 Avill probably be found there, however, and have perhaps been 

 considered as parts of the Cretaceous or of the lower Miocene 

 formations. 



Fossils. — The limestone of St. Bartholomew is rich in fossils, 

 but generally in a bad state of preservation. Also in Trinidad 

 Eocene fossils have been found. The age of St. Bartholomew 

 is, beyond any doubt, that of the Calcaire Grossier of Paris. 

 There occur a large Cerithium, identical with or nearly allied 

 to C. giganteum, a large Nerita allied to N. conoidea, and several 

 species of Voluta, Rostellaria, Phorus, Cyprcea, Natica, etc. 

 My collections of fossil mollusks were sent ten years ago to Prof. 

 Carl Mayer, of Zurich, for determination ; but he has not yet 



* See Nugeni, Descr. of Antigua ; Trans. London Geol. Soc, 1st Ser. 

 Vol. V, p. 459, 1841. 



Howey, Geology of Antigua, Am. J. Sci., XXXV, p. 75, 1839. 

 Duncan, Quart. J. G. S., XIX, p. 408, 1868. 



