632 



XI. FORMATION OF MURIATIFEROUS CLAY (WITH 

 BITUMEN AND LAMELLAR GYPSUm) OF THE PE- 

 NINSULA OF ARAYA. 



This soil presents a striking analogy with 

 salzthon or leberstein (muriatiferous clay), which 

 I have represented as accompanying gem-salt in 

 every zone *. In the salt-pits of Araya (Haraia), 

 it had attracted the attention of Peter Martyr 

 d'Anghiera, at the beginning of the 16th cen- 

 tury (Vol. iii, p. 204). It probably facilitated 

 the rupture of the earth, and the formation of the 

 gulph of Cariaco. The clay is of a smoky co- 

 lour impregnated with petroleum, mingled with 

 lamellar and lenticulary gypsum, and some- 

 times traversed by small veins of fibrous gyp- 

 sum. It incloses angular masses, and less fri- 

 able, of dark brown clay, with a slaty fracture 

 sometimes conchoid (Vol. ii, p. 266). The 

 muriate of soda is found in parts invisible to 

 the naked eye. The relations of position or 

 superposition of this soil with tertiary rocks 

 does not appear to me sufficiently clear to en- 

 able me to pronounce with certainty on this 

 element, the most important of positive geog- 

 nosy. The co-ordinate layers of gem-salt, mu- 

 riatiferous clay, and gypsum, present the same 



* Humboldt, Essai geogn., p. 241, Leonhard, Characteristik 

 der Fdsarten, p, 362. 



