1878.] 45 [Crosby. 
elevation, the principal of which, called the Northern Mountains, 
skirts the northern coast with a breadth of from six to ten miles, and 
a mean altitude of about two thousand feet, thirty-one hundred feet 
being the maximum elevation. 
These mountains, standing like a a wall between the Caribbean 
Sea and the low lands to the south, are composed of crystalline or 
semi-crystalline rocks, which are undoubtedly of great antiquity, the 
most recent dating, probably, from the lower Paleozoic. The re- 
mainder of the island is formed of much newer rocks; — older Cre- 
taceous, the “Older Parian” of Wall and Sawkins, and lower and 
middle tertiary, the ‘‘ Newer Parian” of the same authors. The ter- 
tiary beds largely predominate, the Cretaceous rocks occurring on 
the surface only in two narrow discontinuous belts. These mark the 
positions of prominent anticlinal axes, and form the main part of 
the other ranges of elevated land above indicated. One of these 
lines of hills lies about midway between the Northern Mountains and 
the southern coast, and ranges in height from five hundred to one 
thousand feet, while the third and least important range stretches 
along the south shore, with a maximum altitude of only seven hun- 
dred feet. 
From the time of Humboldt to the present day, all observers have 
agreed that the Northern Mountains of Trinidad are but the eastern 
extension of the great littoral cordillera, or serrania, as the Spanish 
call it, of Venezuela, which presents a bold front to the Caribbean 
Sea for upwards of three hundred miles, and then bends south- 
westerly to form one of the two main branches of the Andes. 
Bordered by this serrania on the north and west, and by the 
Orinoco on the south, is an extended plain, or llano, having a flat or 
gently undulating surface which, nowhere more than a few hundred 
feet above the level of the sea, is, on the east, and especially in the 
delta of the Orinoco, hardly sufficiently elevated to be regarded as 
dry land. This great plain is composed of secondary and tertiary 
rocks, and the recent deposits of the delta of the Orinoco. Accord- 
ing to the published! observations of Mr. Wall, the secondary and 
tertiary strata, in the eastern half of this plain at least, are the 
chronological equivalents of the rocks of Trinidad. But the two 
formations are developed in different proportions on the main land. 
‘The Cretaceous beds are confined to the northern half of the plain, 
where they have a great thickness, forming a belt fully forty miles 
wide, which reaches high up on the serrania, constituting at some 
1 Appendix to the “ Report ou the Geology of Trinidad,” 
