HILL: GEOLOGY OF JAMAICA. 179 
mation may be about 200 meters. The formation of the yellow limestone, 
essentially marine in character, seems to have been terminated by river-mouth 
deposits, since its highest strata consist of shells and carbonated clay slates, 
containing brackish water. At this period the formation must have been almost 
on a level with the surface of the sea, but after it, during the deposition of the 
white limestone, there was presumably a great epoch of depression ; the yellow 
limestone must have descended to considerable depth to allow the formation of 
800 meters of white limestone. A remarkable peculiarity becomes apparent at 
the surface of the yellow limestone. After the primitive forest has been cut 
down, no other trees grow on it, but only a graminea (Anatherum bicorne). 
This phenomenon is so characteristic that it indicates the boundaries of this 
formation. Owing to the extraordinary porousness of the white limestone, 
Water readily seeps through it, and, unless carried off by underground flow, it 
descends until it reaches the impervious clay of the yellow limestone, and there, 
under appropriate conditions, gushes out of the ground. 
“ Among the common fossils of this formation are Cardium, Ostrea, Trochus, 
Natica, Cerithium, Conus, Serpula, Echinocyamus, Echinolampus, Orbitoides, 
and Corals,” 
Every detail above noted corresponds exactly with the character of the 
Cambridge beds of Jamaica. 
Formations allied to the deep water Montpelier beds of Vicksburg age 
(late Eocene of old writers, early Oligocene of Heilprin and Dall) con- 
Stitute an especially important landmark in Antillean history, and have 
wide occurrence. White limestones made up of Globigerina chalks or 
White siliceous deposits composed of Radiolaria occur in Cuba, Haiti, Bar- 
bados, and Trinidad. In Barbados the Globigerina chalks grade down 
mto pure Radiolarian earths, constituting with them a related and con- 
tinuous formation, which in turn overlies the older Eocene Scotland for- 
Mation, composed of land derived sediments like the Richmond beds, 
ad are folded together with them in the most complete mountain struc- 
ture, This association of the Globigerina and Radiolarian beds in Bar- 
bados establishes the intimate relations of the deposits. 
At Baracoa in the northeast part of Cuba, and Port Jérémie, on the 
North coast of the southeastern peninsula of Haiti, Radiolarian earths 
cur in great abundance. I was so fortunate in my explorations of 
Cuba as to ascertain the exact stratigraphic occurrence of these Radiola- 
vian earths unconformably beneath the late or Bowden Oligocene, then 
Called Miocene by Dall.! In the light of my later researches in Jamaica, 
x ! Notes on the Geology of the Island of Cuba, Bull. Mus. Comp. Zoöl., Vol. 
AVI. No, 15, Cambridge, 1895, p. 253, Pl, I. Fig. 5. 
