hill: geology of Jamaica. 173 



Antillean history, representing as it does the commencement of a con- 

 secutive sequence of events from late Cretaceous time to the present. 

 It is clearly the debris of a vast volcanic extrusion which in late Creta- 

 ceous time completely obliterated and revolutionized all the antecedent 

 relief. The age of this eruptive epoch is clearly late Cretaceous. 



In San Domingo,^ St. Thomas,'^ and Porto Rico, these formations are 

 associated with limestone beds and Cretaceous fossils in part, resembling 

 in species and faunal associations those of Jamaica, and in part contain- 

 ing species not found in the latter island. In Cuba^ both the Jamaican 

 and continental types of Cretaceous faunae are found. 



The data seem to point to the fact that the whole region of the Great 

 Antilles proper, including the Virgin Islands, St. Croix, and St. Bar- 

 tholomew, was the site of active vulcanism in late Cretaceous time. 



The extent or outline of the Antillean volcanic disturbance of late 

 Cretaceous time cannot be delineated. It is an important fact that no 

 Cretaceous fossils or formations analogous in age to the Blue Mountain 

 Series are known to occur in the Caribbee Islands proper and Barbados. 

 There is slight evidence, however, that the Cretaceous rocks and fossils 

 of Central America are of the Antillean facies. The sparsely developed 

 Cretaceous formations of Central America known to occur only in the 

 Chiapas-Guatemala district as reported by Sapper,* and the San Miguel 



1 From San Domingo, Gabb has reported a serrated oyster, Trigonia, Turritella, 

 Ancillaria, Piignellus (1), Mactra, Pterocera, Cucullsea, Lima, an Ammonite, and 

 Baculites from beds of limestone in the River Maniel. Tippenhauer (Op. cit., 

 pp. 84, 85) gives the following note on the Cretaceous of San Domingo : " The 

 San Juan valley on Samana, the Pico Gallo on the Central range, the region of 

 Tablasas in the south, are types of this secondary formation. These masses, up 

 to 300 m. thick, form a zone around the highest elevations. Besides vast, com- 

 pact gray-blue and dark limestone masses, there occur marl and sand strata. 

 The ordinary fossils are Hippurites, Nerinea, and Actaeonella, The compact 

 limestone often encloses Radiolites up to seven feet long. In places the limestone 

 has been strongly metamorphosed by the influence of plutonic rock ; in such cases 

 it resembles serpentine, is exceedingly dense, and has lost almost all its fossils 

 by obliteration ; it is also for the most part whiter." 



2 The beds of St. Thomas, according to Cleve, contain the fossils Nerinaea, 

 Actaeonella, Ammonites, Trochus, Pectunculus, Limopsis, Opis, Venus, Astarte, 

 Corbula, etc., of Cretaceous age. Geology of the Northeastern West Indian Isl- 

 ands, 1871, p. 5. 



3 In Cuba the Cretaceous fossils, according to Salterain, are Holectypus, Discoidea, 

 Cassidulus, and Codiopsis ; and, according to G. F Matthew, Ostrea, Exogyra, 

 Inoceramus, from a locality in the Cienfuegos road, and a Hippurite limestone com- 

 posed of Caprinella and Caprotina, corals, a large Oliva, a Conus, an oyster of the 

 type of 0. crisfati, Echini, and sponges from Limones. 



* Grundziige der physikalischen Geographic von Guatemala, p. 9. 



