Vol. 57.] PHYSlCAt DEVELOPMENT OP ANGtriLlA, ETC. 525 



accumulation of volcanic tuffs and breccias, including beds of 

 limestone, all of which have been more or less altered by the 

 infiltration of siliceous waters, during the period of dislocation and 

 secondary volcanic activity, when they were also penetrated by 

 dykes. Any other explanation would place the formation out of 

 harmony with the geological history of the area. This conclusion is 

 supported by the investigation of Mr. Cleve^ in St, Eartholomew, 

 where he found, resting on the same kind of igneous basement, a 

 great thickness of igneo-sedimentary strata, composed of breccias, 

 conglomerates, and scoriaceous layers, varying in texture from 

 fine-grained to coarse, in which latter case angular and rounded 

 porphyritic fragments were commingled with finer material. The 

 series contains intercalated beds of dark, very hard and compact lime- 

 stone with cubical cleavage. The limestones are fossiliferous. Both 

 these and the tuff's may be found silicified, but apparently to a less 

 extent than in St. Martin. So too the limestones in St. Bartholomew 

 seem to be more subordinate to the rest of the mass than in 

 St. Martin. We have also seen that the old eruptive basement of 

 Antigua is succeeded by a great accumulation of tuff, with intercalated 

 beds of fossiliferous limestone which have been silicified. The 

 recurrence of the same succession in the three neighbouring islands, 

 in two of which their contained fossils show a common period 

 of accumulation, suggests that the strata in St. Martin belong to 

 the same age, a conclusion formed by Mr. Cleve so far as St. 

 Bartholomew and St. Martin are concerned. 



In St. Bartholomew, Mr. Cleve found numerous fossils, mostly 

 in a poor state of preservation, among which the corals and 

 foraminifera were abundant. These, if studied, would probably be 

 more valuable in identifying the horizon than the molluscs, the 

 poor preservation of which renders the specific determination 

 difficult : of these he names a number of genera found in the 

 limestones. He obtained two echinoderms — Macropneustes and 

 Echinolampas ovum-serj>entis, Guppy, the latter also occurring in 

 the San Fernando Beds of Trinidad — and a decapod, Banina, 

 Among the molluscs was a species of Argiope and another of 

 Terehratula (apparently T. carneoides^ Guppy, also found in the 

 Trinidad beds), a large Nerita (near N. conoidea, Lamk.), and also a 

 large (7m^/^mm (apparently C. giganteum^ Lamk.), both of the Paris 

 Eocene. From the palseontological evidence he concluded that the 

 formation is the equivalent of the Middle Eocene of Europe. Thus 

 the age of the tuff-limestone series in St. Bartholomew is shown to be 

 practically the same as that of the tuff-limestone series in Antigua, 

 or just below the beds which are there considered to be Oligocene, 

 this being as close a correlation as the present data afford. Although 

 the formation has been subject to greater variations and alterations 

 in one locality than in another, the distribution in the neighbouring 

 islands indicates that the same conditions prevailed throughout the 

 area during the early Tertiary Period. 



In Anguilla, underlying the limestones along the eastern side of 



1 Handl. k. Svenska Vetenak. Akad. vol. ix (1870) no. 12, p. 24, 



