198 bulletin: museum of comparative zoology. 



similar phenomena indicating harmony of elevation and submergence in 

 previous epochs can be made out. The cut plains of the north half of 

 Antigua and the Grande Terre of Guadeloupe clearly show that regional 

 elevations have taken place after the close of Miocene time, followed 

 by erosion epochs and a Pliocene or early Pleistocene subsidence some- 

 what analogous to the Lafayette events. The bordering reefs formed on 

 the rising platforms at Aftrie Galante and Desirade, and the double terrace 

 structure of Barbuda show that these islands participated in the general 

 Post-Pleistocene elevation of all the West Indies. Prior to the latest 

 Miocene the details of composition and history were entirely dissimilar, 

 and unlike the events of Eocene and Oligocene history of the Great 

 Antilles. 



During all these epochs from the Eocene to the present the volcanoes 

 of the Caribbee chain have been piling up the vast heaps of stratified 

 tuff that form not only the eminences but much of the extensive sub- 

 marine platforms of the region. 



The island of Barbados, standing 125 miles east of the main Wind- 

 ward circle, and separated from it by over 2,000 fathoms of water, is 

 entirely unlike the Antillean, Windward, or Central American provinces 

 in history and geomorphology. It has no known volcanic rocks. 



These facts concerning the geology of the Lesser Antilles clearly show 

 that piling up of volcanic material began there as far back as the Eocene 

 epoch, and that the islands have participated in the later epeirogenic 

 movements of Pleistocene or recent time. Hence we may conclude : — 



1. The Windward Islands represent a distinct volcanic province, dis- 

 similar in lithologic composition from the older volcanic phenomena of 

 the Antillean province, and somewhat similar to the volcanic summits of 

 Central America. 



2. Their visible history dates back at least as far as Eocene time, and 

 their periods of greater eruptivity ceased in the Pleistocene. 



PART VI. 



Changes of Physiography in Tropical America, bearing 

 upon the History of the "West Indian Islands. 



The interpretation of the present configuration and history of the An- 

 tillean and Central American regions is a difficult task, and involves 

 the analysis of many groups of data, embracing several distinct fields 

 (^f research. Biology, paleontology, oceanography, structural geology, 



