122 J. W. SPENCER — RECONSTRUCTION OF ANTILLEAN CONTINENT. 



of the continent cliatomaceous and foraminiferal earths occur in the mid- 

 dle Miocene beds. This is true also in Jamaica, and apparently of Cuba, 

 where radiolarian deposits at the eastern end of the island appear to be- 

 long to the same date. In Barbadoes Messrs Jukes-Browne and Harri- 

 son* have described great deposits of radiolarian earths. They assign 

 the oceanic deposits provisionally to the Pliocene, but do not object to 

 the earlier age, as they had not the data for settling the question, but they 

 established the succession of insular strata and the wonderful amount of 

 subsidence. The related roCks in the island do not form a series for close 

 comparison of the age of the abysmal earths. They lie on the greatly 

 eroded surfaces of what may be Cretaceous deposits (judging from dy- 

 namic conditions) and unconformably underlie limestones of probably 

 the latest Pliocene epoch, if correctly correlated with the rocks of the 

 Greater Antilles. Under these conditions it may not be straining the 

 evidence to place the Barbadian earths in the Miocene system, under 

 which the geomorphic changes of the whole region would be in harmony. 

 Accordingly, in the Miocene period there appears to have been a great 

 subsidence, extending from the West Indies to New Jersey (apparently 

 commencing la little earlier in Barbadoes and later in the north), the be- 

 ginning of the stupendous oscillations that culminated in the continental 

 Antilles and ended with the modern depression of the region of the 

 West Indies. 



The Antillean Continental Extension in the Pliocene Period. 



Throughout most of the Pliocene period there was an extensive ele- 

 vation and development of the Antillean region. In part, this eleva- 

 tion may have commenced in the later Miocene ; for, according to the 

 paleontologic studies of Mr Robert Etheridgef on the fossils of An- 

 tigua (Eocene, according to Jukes-Browne), Anguilla and part of Trin- 

 idad, the upper Miocene rocks are absent, either from not having been 

 deposited or from subsequent denudation. Littoral Miocene beds are 

 also wanting in Barbadoes and probably in other regions. In Cuba, San 

 Domingo, Jamaica and other places, as in .Florida, the upper Miocene 

 beds are found. In places the earliest Pliocene beds appear to be also 

 found as a stratigraphic unit with the Miocene in Florida (Dall) ; J con- 

 sequently the great continental elevation in some regions seems to 

 have commenced at the end of the Miocene and in other places in the 

 early Pliocene period ; but the Tertiary seas were being gradually re- 

 stricted, from the earlier Eocene times, along the continental margin. 



* The Geology of Barbadoes, by A. J. Jukes-Browne and J. B. Harrison, Quar. Jour. Geol. Soc. 

 London, vol. xlvil, 1891, pp. 197-250, and vol. xviii. 1892, pp. 170-22G. 

 fSee the reports on San Domingo and Jamaica. 

 X Bull. U. S. Geol. Surv., no. 84, cited before. 



