GEOLOGY OF PART OF CUBA. 205 
assumes, therefore, in its behalf, is that it suffices for the outline of a geological recon- 
noissance; that it exhibits. sufficiently the position of the most remarkable mountain 
masses; and that it illustrates the localities of the rock formations, and the direction of 
the mineral veins within the area submitted to examination, 
Of late years, enterprise, at home and abroad, has unfortunately received so severe a 
check, that no progress has been made in cultivating the really valuable mineral resources 
of this part of the Island. They remain, therefore, pretty nearly in the state in which 
they were left by the writer, a few years ago. It is not improbable but that a faithful 
sketch of what fell under his observation, may have some influence in directing attention 
to that fruitful source of industry. 
The analytical examination of the mineral substances was performed by his associate, 
Mr. Clemson of this city, who contributed some valuable aid in these investigations. 
A copy of this memoir and of the map, and of every essential detail, has been in the 
hands of a scientific friend, now a resident of this district. He has taken the pains to 
verify the data upon the spot, which inspires the writer with the greater confidence in 
making public this communication. 
GEOLOGICAL CHARACTER OF THE GIBARA REGION. 
On landing at the Port of Gibara, the first rock that we perceive is an ancient coral 
reef, forming a belt of no great breadth, attaining an elevation of twenty or thirty feet 
above the sea; and rather more than that above the level of living corals, in the reefs that 
border the northern coast of this island. 
Proceeding south, into the interior, we cross compact white limestones, which are far 
older than the agglomerated coral limestone we have just quitted. 
To these succeed belts and beds of metamorphic rocks, having a magnesian base. 
Their direction appears to average north-east or east-north-east, but all bear the impress 
of great change of position, structure and arrangement. As we proceed we perceive 
rocks allied to diabase, trap, and porphyry, exhibiting additional evidences of disturb- 
ance. Then follow a numerous suite of stratified rocks. They consist of varieties of 
serpentine, ophiolite, metalloide diallage, (euphotide) hypersthene, diorite, schillerspar, 
feldspar, and amphibole, variously modified and blended. To these may be added ferrugi- 
nous opal, jasper, jade, chalcedony, quartz, porphyry, calcareous tufa and breccia, diabase 
or greenstone, and conglomerates composed of fragments of several of these substances. 
Beds of dark green claystone, and soft dark rocks, modified by heat, alternate with the 
harder magnesian and hypersthene rocks, and with enormous masses of white metamor- 
phic limestone; the latter of which attains a greater elevation than any other. With the 
exception of a few partially obliterated corals in the limestone, the rest are wholly devoid 
of organic remains. 
VOL. IX.—-5 § 
