﻿GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 607 



the Atlantic Ocean must have had access to these oceanic basins 

 during a part if not all of these periods. 



According to Hill, vulcanism existed prior to later Mesozoic in 

 Guatemala, Oaxaca, Jamaica, and the Andes, and perhaps in Cuba 

 and Haiti, as well as in the Cordilleras of North America. Probably 

 there was vulcanism in Porto Rico, the Virgin Islands, St. Croix, St. 

 Martin, St. Bartholomew, and Antigua. In the two last mentioned 

 islands there are volcanic rocks older than Eocene sediments. 



At the close of the Cretaceous there was general emergence of the 

 Coastal Plain, an event probably due to dias trophism and a resultant 

 of Laramide mountain making. 



EOCENE AND OLIGOCENE. 



The West Indian islands, because no old Eocene sediments are 

 known in any of them except Trinidad, which is South American in 

 its relations, are supposed to have stood above sea level at that 

 time. In Cuba and Jamaica there are Upper Cretaceous and late 

 Eocene sediments without the intervention of early Eocene deposits. 

 p During later Eocene (Ludian) and middle and upper Oligocene 

 (Rupelian and Aquitanian) time there was extensive submergence 

 in the West Indies and interoceanic connection through a number 

 of straits across Central America. There may have been mterocanic 

 connection din-ing lower Oligocene (Lattorfian) time, but this is not 

 established. The maximum submergence was in middle Oligocene 

 (Rupelian) time. Vulcanism was widespread in Central America 

 and the Antilles during Eocene and probably also during earlier 

 Oligocene time. The line of the great Mexican volcanoes had its 

 inception at the close of the Cretaceous, near the beginning of the 

 Tertiary, according to Felix and Lenk. 



In Jamaica, Cuba, St. Bartholomew, and Antigua the later Eocene 

 age of some of the volcanic rocks is established. There was between 

 the upper Eocene and the middle Oligocene deposition periods great 

 deformation in the Antilles. The folding in the principal mountains 

 of Jamaica, the Sierra Maestra of Cuba, and apparently those of 

 Haiti, Porto Rico, the Virgin Islands, and St. Croix appears to have 

 taken place at this time. Diastrophism seems also to have been 

 active in Chiapas, Tabasco, Peten, Guatemala, Nicaragua, Costa 

 Rica, and Panama. 



MIOCENE. 



During older Miocene (Burdigalian) time apparently there was in 

 places connection between the Atlantic and Pacific oceans, as is 

 shown by deposits of this age containing fossils of Atlantic affinities 

 on the Pacific coast of Costa Rica ^ and Nicaragua, and perhaps at 



' Romanes, J., Geology of a part of Costa Rica, Geol. Soc. London Quart. Joum., vol. 68, pp. 124, 125, 

 1912. 



3714^— 19-Bull.'103 5 



