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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The gneiss-granite of the Sierra Parime is covered in some few places
(between the Encaramada and the strait of Baraguan and in the island
of Guachaco) in its western part with an olive-brown sandstone,
containing grains of quartz and fragments of felspar, joined by an
extremely compact clayey cement.
This cement, where it abounds, has a
conchoidal fracture and passes to jasper. It is crossed by small veins
of brown iron-ore, which separate into very thin plates or scales. The
presence of felspar seems to indicate that this small formation of
sandstone (the sole secondary formation hitherto known in the Sierra
Parime) belongs to red sandstone or coal.* (* Broken and intact
crystals of feldspar are found in the todte liegende coal-sandstone of
Thuringia. I observed in Mexico a very singular agglomerated felspar
formation superposed upon (perhaps inclosed in) red sandstone, near
Guanaxuato.) I hesitate to class it with the sandstone of the Llanos,
the relative antiquity of which appears to me to be less
satisfactorily verified.
6. FORMATION OF THE SANDSTONE OF THE LLANOS OF CALABOZO.
I arrange the various formations in the order which I fancied I could
discern on the spot. The carburetted slate (thonschiefer) of the
peninsula of Araya connects the primitive rocks of gneiss-granite and
mica-slate-gneiss with the transition strata (blue and green slate,
diorite, serpentine mixed with amphibole and granular greenish-grey
limestone) of Malpasso, Tucutunemo and San Juan. On the south the
sandstone of the Llanos rests on this transition strata; it is
destitute of shells and composed, like the savannahs of Calabozo, of
rounded fragments of quartz,* kieselschiefer and Lydian stone,
cemented by a ferruginous olive-brown clay.
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