OF CUMANACOA 391 



plains (llanos), steppes, and deserts,, have not that uniform 

 tertiary formation which has been too generally sup- 

 posed. 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 ap- 

 proach, according to the analogy of the observations made 

 by M. Roziere in Egypt, the sandstone of Calabozo, or 

 tertiary nagelfluhe. 



VII. FORMATION OP 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 car- 

 buretted and slaty marl, with pyrites ; (2) quartzose sand- 

 stone, alternating with very thin strata of clayey slate ; 

 (3) gypsum with sulphur, near Guire, in the Grolfo 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. 



The only petrifactions of shells which I found in this 

 limestone formation consist of a heap of turbinites and 

 trochites, on the flank of Turimiquiri, at more than 68C 



the limestone with nummulites, of Siwa. The primitive rocks from 

 which the fine-grained marble was believed to be extracted, if there be no 

 deception in its granular appearance, are far distant from the Oasis of 

 Siwa. 



* This sandstone contains springs. In general it only covers the 

 limestone of Cumanacoa. but it appeared to me to be sometimes en* 

 closed. 



