178 GEOGRAPHIC RELATION OF THE THREE AMERICAS 
parts of Nicaragua, Guatemala, Honduras, Yucatan, Chiapas, 
and southern Oaxaca, and through the Great Antilles. These 
mountains are made up of granites, eruptives, and folded sedi- 
mentary rocks of Paleozoic, Mesozoic, and Cenozoic age in 
Guatemala and southern Mexico ; of Mesozoic and Cenozoic 
age in the Antilles, Costa Rica, Venezuela, and Colombia; and 
of Cenozoic age in Panama. 
The two elongated submarine ridges Ghe so-called Mistero.sa 
and Rosalind banks) stretching across the Caribbean from the 
Antilles to the Central American coast, between the Sierra Mae-- 
tro of Cuba and the gulf of Honduras, and from Jamaica to cape 
Gracios a Dios respectively, separated by the sulimarine valley, 
18,000 feet in depth, known as “ Bartlett Deep,” have a suggestive 
and remarkable resemblance to these east-west corrugations of 
the land ; indeed Seebach long since suggested that these ridges 
directly connected the mountains of the Antilles with those of 
Guatemala and Honduras. 
Thus the Caribbean sea is almost entirely surrounded by the 
east-west trending mountains and submarine ridges of the Antil- 
lean type; the Windward islands, marking the eastern inlet of 
the sea, are largely volcanic necks. 
A distinct class of mountains, independent of great lines of 
folding of the earth-crust, are the volcanoes. These have grown 
by e.xtrusion and accumulation; .sometimes they are parasitic 
on the folded mother-sy.stems, sometimes independent of them. 
They belong to the great area of igneous activity which, since at 
least as earl\' as the beginning of Tertiary time, has marked the 
whole we.stern half of the North American continent, the Carib- 
bean, and the northern and we.stern sides of the Andean region. 
Although they blend, the volcanic ejecta of this great belt may be 
classified for convenience in two distinct age categories, which 
may he called the quiescent and the active volcanic groups. 
The active volcanic groups occur in four widely separated 
regions; 1. The Andean group of volcanoes of the equatorial 
region of western South America, rising above the corrugated 
folds of the northern termination of the predominant South 
American cordilleras. 2. The chain of some twenty-five great 
cinder cones which stretch east and west across the southern 
end of the Mexican plateau, protruding parasite-like upon the 
terminus of the North American cordilleras. 3. The Central 
American group, with its thirty-one active craters, growing diago- 
nally across the western ends of the east-west folds of the Antil- 
