It becomes thicker, and mixed with sand, as we approach the
Rio Apure; for near Calabozo it is one toise thick, near the mission
of Guayaval five toises, which may lead to the belief that the strata
of red sandstone dips towards the south. We gathered in the Mesa de
Pavones little nodules of blue iron-ore disseminated in the clay.
A dense whitish-gray limestone, with a smooth fracture, somewhat
analogous to that of Caripe, and consequently to that of Jura, lies on
the red sandstone between Tisnao and Calabozo.* (* Does this formation
of secondary limestone of the Llanos contain galena? It has been found
in strata of black marl, at Barbacoa, between Truxillo and
Barquesimeto, north-west of the Llanos.) In several other places, for
instance in the Mesa de San Diego, and between Ortiz and the Mesa de
Paja,* (* Also near Cachipe and San Joacquim, in the Llanos of
Barcelona.) we find above the limestone lamellar gypsum alternating
with strata of marl. Considerable quantities of this gypsum are sent
to the city of Caracas,* which is situated amidst primitive mountains.
(* This trade is carried on at Parapara. A load of eight arrobas sells
at Caracas for twenty-four piastres.)
This gypsum generally forms only small beds, and is mixed with a great
deal of fibrous gypsum. Is it of the same formation as that of Guire,
on the coast of Paria, which contains sulphur?
