222 MR. JTJKES-BROWNE AND PEOE. HARRISON 



The Barbadian sequence, however, taken by itself furnishes us 

 with valuable historical material. It is not like that of certain 

 Pacific islands where Oceanic Deposits are the oldest stratified rocks 

 and no base other than volcanic rocks has yet been found. Barbados 

 has a history that is anterior to the Oceanic episode ; its great series 

 of sandstones and clays testify to the close proximity of a large 

 land-area in early Tertiary time, and the existence of similar 

 terrigenous deposits in Trinidad, Hayti, Cuba, and Jamaica may be 

 taken as strong evidence that there was at that time continental 

 land in the Caribbean region. In Jamaica the Eocene Series alone 

 is estimated at 2500 feet, and it consists of shales, sandstones, and 

 trappean conglomerates which show that a large area of land was 

 undergoing detrition. 



Our view of Caribbean geography therefore starts with a period of 

 shallow water and with conditions that appear to have been con- 

 tinental, but we do not think that the present hydrographic 

 contours of the Caribbean Sea afford any clue to the trend or outline 

 of this early Tertiary land. 



In Trinidad and San Domingo these conditions seem to have 

 been maintained during Mid-Tertiary time, but in Jamaica there 

 was submergence allowing a large area and a considerable thickness 

 of yellow limestone and marl to be accumulated. This subsidence 

 was certainly continued during the formation of the succeeding 

 White Limestones, which in many places overlap and extend 

 beyond the yellow limestones. Some of these Pliocene white lime- 

 stones are of oceanic oriizin, though their extent and thickness are 

 at present unknown. The white foraminiferal limestone of San 

 Domingo which caps the highest Miocene beds ^ may possibly be of 

 the same age, and we have already stated that we regard the Oceanic 

 Deposits of Barbados and Trinidad as belonging to the same period 

 of geological time. 



It is therefore in the Pliocene period that we find proofs of a very 

 deep submergence of the whole Caribbean region ; for it will 

 be borne in mind that Jamaica is 1100 miles west of Barbados, 

 that Jamaica itself is 150 miles long, and that its western end is 

 only 400 miles from the nearest point of Central America, while 

 the western end of Cuba is only 130 miles from Yucatan ; hence it 

 is very probable that the submergence which produced oceanic 

 conditions in Jamaica extended also to Central America, and we shall 

 be surprised if deep-water marls and limestones of Pliocene age 

 are not eventually found in that region. 



It is known that both in Panama and Nicaragua there are 

 Tertiary marine deposits of various dates. Prof. Agassiz informs 

 us that the fossils obtained by Dr. Maack at heights between 300 

 and 763 feet on the Isthmus of Darien are of Miocene age, and that 

 he mentions limestones near Empire Station on the Panama Pailroad 

 which are filled with such fossils ; ^ but he also obtained post- 



^ Gabb, in Trans. Amer. Phil. Soc. 1881, n.s, vol. xy. p. 103. 

 ^ Pub. Doc. Nayy Dept. U.S.A. 1144, vol. v. pp. 155-175. 



