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 other outcrops which 
belong to the Montpelier beds; from the literature we infer that they 
constitute the summit formation of the John Crow Ridge. 
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 reconnojssances 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 Long 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 
beds above the undoubted Lower Eocene of the Cambridge formation, 
and below the undoubted late Oligocene of the Bowden formation, 
together with the occurrence of Orbitoides mantelli. 
1 Jamaican Reports, p. 53, 
