70 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



the rocks of the Coastal Series. They contain few macroscopic fossils 

 by which their age can be independently determined, but this is fixed 

 by their microscopic fossils and their position between including fossilif- 

 erous horizons, — the underlying Cambridge beds and the overlying 

 Bowden gravels and marls. 



In general, the Oceanic Series occupies most of the Plateau region, 

 which practically includes all the island under 3,000 feet in altitude 

 outside of the Blue Mountain district, except its immediate coastal 

 borders. In the mountainous region of eastern Jamaica these rocks 

 occur as a high piedmontal peripheral border around that end of the 

 island. In the western half of the island the beds of the Oceanic Series 

 completely cover the old Blue Mountain Series and occupies the higher 

 summits of that portion of the island. 



Owing to the elevation of the Plateau region which took place after 

 the deposition of these beds, and the subsequent contraction of its 

 oceanic borders by erosion and subsidence, the coastward extension of 

 the rocks is truncated and partially embedded near the littoral by the 

 still later formations of the Coastal Series, which are deposited uncon- 

 formably against them. 



The Montpelier Beds. — The Cambridge beds north of Cambridge are 

 succeeded by stratified white limestones and marls containing nodules 

 of flint. The limestones are of non-crystalline (chalky) texture, and 

 usually break with dull, earthy, conchoidal fracture. The texture, frac- 

 ture, and presence of flints distinguish this formation from others of 

 the great series of white limestones of many ages, which, above the 

 Cambridge beds, dominate in the rock structure of Jamaica. 



Concerning the grosser lithology of the ]\Iontpelier beds, little can be 

 added to the excellent description of them in Hanover and Westmore- 

 land, given by Charles B. Brown as a portion of the ''White limestone," 

 as follow s : ^ — 



" It consists of thin beds of white limestone interbedded with a soft 

 white chalky marl, the limestone beds invariably containing nodules of 

 flint. The limestones are chiefly soft, but seldom compact or crystal- 

 line ; they form thin beds, which var}' from a few inches to four feet in 

 thickness, and are much disturbed, so as to dip in almost every direc- 

 tion over small areas. The marl beds being interstratified with these 

 of course show the same disturbance and dips, and are similar to them 

 in thickness. The flints and chert contained in the limestone beds lie 

 usually in flattened nodular masses in lines of stratification, and are 



1 Jamaican Reports, pp. 250, 251. 



