The Great Masses Of Sulphur Found In The Layers, Almost Entirely Clayey, Of The Steppes (At Guayuta, Valley Of San Bonifacio, Buen Pastor, Confluence Of The Rio Pao With The Orinoco) May Possibly Belong To The Marl Of The Gypsum Of Ortiz.

These clayey beds are more worthy of attention since the interesting observations of Von Buch and several other celebrated

Geologists respecting the cavernosity of gypsum, the irregularity of the inclination of its strata and its parallel position with the two declivities of the Hartz and the upheaved chain of the Alps; while the simultaneous presence of sulphur, oligist iron and the sulphurous acid vapours which precede the formation of sulphuric acid, seem to manifest the action of forces placed at a great depth in the interior of the globe.

11. FORMATION OF MURIATIFEROUS CLAY (WITH BITUMEN AND LAMELLAR GYPSUM) OF THE PENINSULA OF ARAYA.

This soil presents a striking analogy with salzthon or leberstein (muriatiferous clay) which I have found accompanying gem-salt in every zone. In the salt-pits of Araya (Haraia) it attracted the attention of Peter Martyr d'Anghiera at the beginning of the sixteenth century. It probably facilitated the rupture of the earth and the formation of the gulf of Cariaco. This clay is of a smoky colour, impregnated with petroleum, mingled with lamellar and lenticular gypsum and sometimes traversed by small veins of fibrous gypsum. It incloses angular and less friable masses of dark brown clay with a slaty and sometimes conchoidal fracture. Muriate of soda is found in particles invisible to the naked eye. The relations of position or superposition between this soil and the tertiary rocks does not appear sufficiently clear to enable me to pronounce with certainty on this element, the most important of positive geology. The co-ordinate layers of gem-salt, muriatiferous clay and gypsum present the same difficulties in both hemispheres; these masses, the forms of which are very irregular, everywhere exhibit traces of great commotions. They are scarcely ever covered by independent formations; and after having been long believed, in Europe, that gem-salt was exclusively peculiar to Alpine and transition limestone, it is now still more generally admitted, either from reasoning founded on analogy or from suppositions on the prolongation of the strata, that the true location of gem-salt is found in variegated sandstone (buntersandstein). Sometimes gem-salt appears to oscillate between variegated sandstone and muschelkalk.

I made two excursions on the peninsula of Araya. In the first I was inclined to consider the muriatiferous clay as subordinate to the conglomerate (evidently of tertiary formation) of the Barigon and of the mountain of the castle of Cumana, because a little to the north of that castle I had found shelves of hardened clay containing lamellar gypsum inclosed in the tertiary strata. I believed that the muriatiferous clay might alternate with the calcareous conglomerate of Barigon; and near the fishermen's huts situated opposite Macanao, conglomerate rocks appeared to me to pierce through the strata of clay.

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