HILL: GEOLOGY OF JAMAICA. 71 



rarely in beds themselves. They are not conliected continuously, but 

 are in long hollow fiat masses, and have all the appearances of having 

 been deposited around or in the substance of some organic form which 

 was embedded in the limestone. These flints are chiefly of a brownish 

 pink, brown, and gray colors. At Knock alva and other places in the 

 vicinity the limestone contains small veins of silica, and also has become 

 so thoroughly impregnated with that substance as to be completely 

 changed into a siliceous limestone." ^ 



Microscopic examinations show that the calcareous beds consist of 

 organic oceanic material, and are composed of the shells of Foraminifera, 

 occasional sponge spicules, and fine crystals and amorphous particles of 

 carbonate of lime, like those usually found in all chalky oceanic deposits. 

 No terrigenous material whatever has been found in any specimens 

 examined. The Montpelier beds are singularly free from molluscan or 

 other visible fossils, except a large species of Orbitoides in its lower 

 beds. Nummulinse have also been found. 



William Hill*^ has studied microscopically a specimen of white lime- 

 stone, Hanover County, which undoubtedly came from the Montpelier 

 beds. This, according to Jukes-Browne and Harrison,^ is an oceanic 

 deposit in which " Thick-shelled Globigerina?, similar to those of the 

 Barbados rocks, are conspicuously abundant, and one or two Radiolarians 

 can be seen in outline." 



Some of the flints are also black or gray in color and flattened, oblong 

 in shape, like those of the Upper Cretaceous of England and Lower 

 Cretaceous of Texas ; others are round and opalescent. The whitened 

 exterior surfaces of many specimens are masses of silicified Forami- 

 nifera, — Orbitoides, Nummulinye, and Miliolidae, — and these can be 

 made out in the interior of some of the specimens collected from Mont- 

 pelier Hill. Similar occurrences of Foraminifera coating the flints have 

 been noted from St Mary. In places they occur in great abundance as 

 requently described in the Jamaican Reports, and are found in no 

 other formation so far as we have observed. Occasionally there are 

 also hard siliceous lumps in the limestone, which suggest that secondary 

 alteration into flints may have been possible. In general, these seem 

 to be silicified lumps of organic skeletal remains. Several specimens of 



^ The description above priven refers to Brown's lower division of the wliite 

 limestone (our Montpelier beds) ; the upper beds (our Brownstown beds) are more 

 compact and massive, and contain fewer interstratified marls. 



« Quart. Jour. Geol. Soc. London, 1891, Vol. XLVIL pp. 248, 249. 

 ) 3 Ibid., 1892, Vol. XLVIII. p. 180. 



