GEOLOGY OF PART OF CUBA. 209 
ourselves surrounded by objects highly attractive by their novelty and by their great 
geological interest. From the midst of the arid savanas, as well as from the lower wooded 
plains, arise those lofty detached mountains of compact marble, whose unusual shapes, 
and whose white, vertical escarpments, contrast strongly with the brown, sunburnt hills 
of serpentine; and confer such a peculiarity on the contour of the coast; and furnish to 
the far-off mariner such conspicuous landmarks. 
On reaching these mountains, their precipitous cliffs appear to be distinctly striated 
or fluted, vertically; having resemblance to clusters of enormous columns, hundreds of 
fect in height. At first we attributed this appearance to the possibility of vertical strata. 
On a nearer examination no trace of stratification appeared. We saw that this columnar 
appearance was simply derived from the erosion of the escarpment, into deep vertical 
grooves. On the mountain of La Silla, this phenomenon is beautifully exhibited. 
When, from its summit, we looked down upon the numerous spurs of this saddle-shaped 
ridge, and upon its surrounding indented masses, we seemed to perceive an assemblage 
of groups of enormous crystals of white rock, distributed over a space nearly a mile broad 
and two miles long; shooting upwards from the dark woods below. From the bases of 
several other mountains equally characteristic views arise; in the resemblance to snow- 
white basaltic pillars, clear of vegetation on their sides; except here and there an aloe, or 
some flowering shrub rooted ina crevice. At a short distance the illusion is equally 
perfect, when we look towards the jagged outline of the crest, it would seem as if an 
entire mountain, a thousand feet in height, constitutes one vast group of crystals. 
The Gibara river is, in many places, crossed by calcareous bands; and, near the great 
anticlinal axis, before adverted to, the masses are frequently traversed by a beautiful 
network of delicate quartz veins. They also exhibit evidence of having been greatly 
shattered, broken up, and distorted. Their fragments have been subsequently re-united 
by siliceous cement; but their original continuity and parallelism of deposite, are nearly 
obliterated. In other cases, all traces of stratification have been removed from the now 
perfectly compact mass. 
Two miles to the south of the plantation of Gzdara arriba, our map shows a couple of 
nearly circular hills, or great mounds, of compact limestone, in the range of La Silla; 
apparently surrounded by, or thrust up from beneath, an area of diabase. ‘The summits 
of these somewhat conical hills, are not altogether solid limestone, but consist of an accu- 
mulation of shattered masses of that rock, piled rudely upon each other. ‘The weathered 
surfaces of these calcareous masses, are worn into deep holes, with intermediate points, 
somewhat dangerous to walk upon. In this respect it exactly resembles the waterworn 
limestone and old coral rock, which on the Cuba coast, are now daily subjected to the 
action of the waves. I may add another instance, more recently observed by me, in the 
case of the Tully limestone of New York, wherever the surface is exposed to the erosive 
action of the waves of Cayuga Lake. But in the hills of our first limestone chain, in the 
great anticlinal axis of Gibara, wherever any vertical escarpment prevails, and even where 
the sides of the detached masses have steep faces, we observed them furrowed in perpen- 
dicular grooves: thus presenting that appearance of columnar arrangement, which we 
before noticed on a more magnificent scale. This rock is sonorous when struck; remind- 
ing us of the musical ringing sound commonly produced by chalk flints. The fracture 
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