Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 3 - By Alexander Von Humboldt And Aime Bonpland.
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These Examples Sufficiently Prove That The Plains (Llanos),
Steppes And Deserts Have Not That Uniform Tertiary Formation Which Has
Been Too Generally Supposed.
Do the fine pieces of riband-jasper, or
Egyptian pebbles, which M. Bonpland picked up in the savannahs of
Barcelona (near Curataquiche), belong to the sandstone of the Llanos
of Calabozo or to a stratum superposed on that sandstone?
The former
of these suppositions would approach, according to the analogy of the
observations made by M. Roziere in Egypt, the sandstone of Calabozo,
or tertiary nagelfluhe.
7. FORMATION OF THE COMPACT LIMESTONE OF CUMANACOA.
A bluish-grey compact limestone, almost destitute of petrifactions,
and frequently intersected by small veins of carburetted lime, forms
mountains with very abrupt ridges. These layers have the same
direction and the same inclination as the mica-slate of Araya. Where
the flank of the limestone mountains of New Andalusia is very steep we
observe, as at Achsenberg, near Altdorf in Switzerland, layers that
are singularly arched or turned. The tints of the limestone of
Cumanacoa vary from darkish grey to bluish white and sometimes pass
from compact to granular. It contains, as substances accidentally
disseminated in the mass, brown iron-ore, spathic iron, even
rock-crystal. As subordinate layers it contains (1) numerous strata of
carburetted and slaty marl with pyrites; (2) quartzose sandstone,
alternating with very thin strata of clayey slate; (3) gypsum with
sulphur near Guire in the Golfo Triste on the coast of Paria. As I did
not examine on the spot the position of this yellowish-white
fine-grained gypsum I cannot determine with any certainty its relative
age.
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