HILL : GEOLOGY OF JAMAICA. 75 



still higher strata of the bluff are apparently the Montpelier beds with 

 flints. East of Port Antonio there are several otlier outcrops which 

 belong to tlie Montpelier beds ; from the literature we infer that they 

 constitute the summit formation of the John Crow Kidge. 



On the south side of the eastern portion of the island beds corre- 

 sponding to the Montpelier have been noted in a locality mentioned by 

 Sawkins,^ near Orange Park, in St. David, where their relations to 

 adjacent formations can be seen, and in Long Mountain back of Kings- 

 ton. In our reconno ssances of this portion of the island, beds ap- 

 parently belonging to this formation were seen between Bath and 

 Bowden. 



No exposure of the Montpelier beds on the south slope in the region 

 between Lonoj Mountain east of Kingston and St. Elizabeth is known. 

 In fact the formation seems to be missing in the Bog Walk and Clarendon 

 sections, though it may be represented there by a hiatus between the 

 Cambridge and Brownstown formations. In St. Elizabeth the beds are 

 again well exposed apparently unconformably below the Brownstown at 

 Springfield and thence to Pisgah. From the details above given it is 

 apparent that before its dismemberment during later erosion this for- 

 mation completely girdled the island and entirely buried the old Blue 

 Mountain Series in the western two thirds of its area. 



The thickness of the Montpelier formation is difficult to determine, 

 owing to lack of continuous exposures. Our observations have led to 

 the conclusion that they do not exceed 1,000 feet. Everywhere these 

 beds show great disturbance, but not to the degree of the Blue Moun- 

 tain Series, usually consisting of more open folds. 



The Montpelier beds are the deepest sediments preserved in the 

 geological structure of Jamaica, and represent the culmination of the 

 great subsidence initiated in the Cambridge epoch. Judging from 

 the rapid transition between the littoral Cambridge formations and 

 the chalks of the Montpelier formation, this subsidence must have been 

 rapid in geologic time. 



The age of the Montpelier beds most probably corresponds to that of 

 the late Eocene (old classification) now called the early Oligocene, agree- 

 ing approximately with the position of the Vicksburg stage of our 

 American Tertiary. This inference is based upon the position of the 

 bed^ above the undoubted Lower Eocene of the Cambridge formation, 

 auq below the undoubted late Oligocene of the Bowden formation, 

 together with the occurrence of Orbitoides mautelli. 



1 Jamaican Reports, p. 53. 



