Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 1 - By Alexander Von Humboldt And Aime Bonpland.
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A Wall Of Rock There Rises Perpendicularly To The Height
Of Eight Hundred Toises.
It is seldom that in a zone where the
force of vegetation everywhere conceals the soil and the rocks, we
behold a great mountain presenting naked strata in a perpendicular
section.
In the middle of this section, and in a position
unfortunately inaccessible to man, two caverns open in the form of
crevices. We were assured that they are inhabited by nocturnal
birds, the same as those we were soon to become acquainted with in
the Cueva del Guacharo of Caripe. Near these caverns we saw strata
of schistose marl, and found, with great astonishment,
rock-crystals encased in beds of alpine limestone. They were
hexahedral prisms, terminated with pyramids, fourteen lines long
and eight thick. The crystals, perfectly transparent, were
solitary, and often three or four toises distant from each other.
They were enclosed in the calcareous mass, as the quartz crystals
of Burgtonna,* (* In the duchy of Gotha.) and the boracite of
Lunebourg, are contained in gypsum. There was no crevice near, or
any vestige of calcareous spar.* (* This phenomenon reminds us of
another equally rare, the quartz crystals found by M. Freiesleben
in Saxony, near Burgorner, in the county of Mansfeld, in the middle
of a rock of porous limestone (rauchwakke), lying immediately on
the alpine limestone. The rock crystals, which are pretty common in
the primitive limestone of Carrara, line the insides of cavities in
the rocks, without being enveloped by the rock itself.)
We reposed at the foot of the cavern whence those flames were seen
to issue, which of late years have become more frequent.
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