206 GEOLOGY OF PART OF CUBA. 
5 ANTICLINAL AXIS—AND LIMESTONE CHAINS. 
In the topographical sketch which was prepared to illustrate this paper, it will be per- 
ceived that two principal and two inferior parallel chains of cavernous limestone moun- 
tains range along this part of the island, in an east-north-east direction. The first or 
northern chain comprehends those lofty, isolated, and singularly shaped mountains which 
are recognised so far at sea: comprehending E/ Paramo, La Silla, Cerro Colorado and 
Llavason, besides some hills of inferior note. One cannot contemplate their remarkable 
outlines without receiving the impression that the masses of which they are composed, 
have been thrust up from below. This conclusion is much strengthened on a more 
particular investigation, when it is discovered that this chain is the centre of a great 
anticlinal arch. From this axis the whole series of rock formations in the country are 
tilted in opposite directions. In the area on the north, forming a belt extending to the 
sea coast, eight or ten miles broad, all the rocks decline at an angle of at least forty-five 
degrees towards the north. On the south side the axis, and to an equal breadth at least, 
the strata all dip at an average angle of sixty-five degrees southward, or in the opposite 
direction to the first.* Of the longitudinal extent of the anticlinal axis we know that it 
is at least thirty miles, that being the extreme limit of the observations made by the 
writer. 
The general range of the anticlinal axis, of the four limestone chains, of the mineral 
lodes and of the rock stratification, have a sufficient correspondence in parallelism; being 
not far from EK. N. EK. and W.S. W. Now if we apply to a map of Cuba, and protract 
this course upon it, we perceive that instead of running longitudinally with the island, it 
traverses it obliquely. The course therefore, of the island being N. 70° W. and that of 
the axis, éc. being S. 60° W., there is an angle between them of 50°. It is essential to 
note this, that it might not be supposed that the axis we have thus far traced, followed 
the prevailing direction of the Island, but rather of a spur from the central mountains. 
The same course of 8. '70° E., if prolonged, follows the central range of the Island of 
Hayti. If there were no change in the course of the copper lodes, and no deflection 
in the stratification, within the region under consideration, they would cut out on the 
south side, not far west of C. de Cruz, which is scarcely probable. It is far more likely 
that, on reaching the Sienitic region of Holguin, the series is deflected to the west, and 
may then follow the general direction of the Island: ‘This is proved by following the 
Gold Lode N. W. of Holguin—which runs N. 55° W. 
We were inclined to the belief that the area which lies to the north of the anticlinal 
axis has undergone a greater metamorphic change than the area to the south. In both 
instances it appeared that the disturbance and igneous alteration of the rocks were greatest 
at the parts which are nearest to the anticlinal axis. Another important circumstance 
* The details of the admeasurements of this southern dip, at the best ascertained positions, show as follows. At the 
mines of Sabana Vieja 70°.—At those of Buena Isabela 63°, 67°—70°—and 73°; at San Augustin mine 55°—60°— 
and 65°.—At Olivo mine almost perpendicular. Limestone hills south of Sabana Vieja, 50°—55°—60°—75° and 80°.— 
Limestone ridges on each side of the copper region, generally 60° to 70°.—At Sao Gibara 50° to 60°. 
We have had fewer opportunities to ascertain the variations in the northern zone; but 45° is the lowest observed angle 
in that direction. 
