HILL: GEOLOGY OF JAMAICA. 197 
Owing to an outbreak of yellow fever the writer's studies of these 
Gaudeloupean islands were limited to the briefest reconnoissance of 
their general features as above enumerated, but they were sufficient to 
warrant the deduction that the following details of the geology as set 
forth by Duchassaing were in general correct. 
These beds consist of three formations, the oldest of which are 
fossiliferous tuffs called by Jones? and Duchassaing the “Pierre à 
ravets" and “sables volcaniques remaniés par la mer." This is com- 
posed of yellow tuff very similar to the oldest stratified rocks of 
Antigua, with few fossils, and the sands contain three species of Mol- 
lusca which Cleve asserts with the enclosing strata greatly resemble 
the Eocene beds of St. Bartholomew.? Above these beds of sedi- 
mentated igneous material there is à hard ringing limestone containing 
Terebratule. Still above the latter, and constituting the surface for- 
mation of most of the Grande Terre are tufaceous marls very much 
resembling those of Antigua, containing Foraminifera, Lunulites, and 
many Mollusks, which Mr. Duchaissaing considered to be “older Pliocene 
in age.” In these beds also occur three species of Echini which were 
hot considered as living in the adjacent waters. The latter beds at 
oldest cannot antedate the Bowden or late Oligocene. Above these in 
Places are non-marine deposits of land wash in which were found the 
famous human remains, and which also contain many fossil species of 
land shells. 
The next and latest formation is the * Formation Madréporique ” of 
Duchaissaing. This is true elevated reef rock or Soboruco, and bor- 
ders all the coasts of Grande Terre as well as constitutes the outlying 
islands of Marie Galante and Desirade.* 
These formations of Eocene and later age all overlie the detrital tuffs 
of the old voleanoes of the Caribbee chain, and demonstrate the antiquity 
of the vulcanism. 
These facts above presented lead me to the following conclusions con- 
cerning the Caribbee Islands. Their geomorphology is entirely different 
from that of the Antillean province except in those features on the Wind- 
ward side recording the events of the last epochs of geologic time. No 
1 Bull. Soc. Géol. France, 2d Ser., 1847, Vol. IV. Part IL. pp. 1093-1100, and 2d 
Ser., 1855, Vol. XIL pp. 753-757. 
2 Histoire physique des Antilles frangaise, Paris, 1822, 
* Op. eit,, p. 44. 
* The reef formation of these two islands was also described by Maclure in 1817. 
See Journ, Phila, Acad. Nat. Sci., Vol. I. p. 135. 
