STBATA or MUlUATlPEEOtrS CLAT. 
395 - 
gularity of the inclination of its strata, and its parallel 
position with the two declivities of the Hartz and thfr 
iipheaved 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. 
XI. FonMATlOJt OP Mt'RTATIPEnOUS ClAT (with BiTU' 
MEN AND LaMEEEAU GyI’SU.m) OP TUB PeNTNSLLA OF 
Aeaa'a. — This soil presents a striking analogy with salzthon 
orleberstein (muriatiferous clay), whicli I have found aceom- 
pan^'ing gem-salt in every zone. In the salt-pits of Araya 
(llaraia), it attracted the attention of Peter Martyr 
d’Anghiera, at the beginning of the sixteenth century. It 
probalaly facilitated the rupture of the earth, and the forma- 
tion of the gulf of Cariaco. This clay is of a smoky colour, 
impregnated with petroleum, iniiiglod with lamellar and 
lenticular gypsum, and sometimes traversed by small -veins 
of fibrous gypsum. It incloses angular and" le.ss friable 
masses of dark brown clay, with a slaty and sometimes con- 
choidul 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 -vvitK 
certainty on this element, the most important of positive 
geology. The oo-ordinatc layers of gem-sa,lt, muriatiferous 
clay, and gypsum, present the same difficulties in both hemi- 
spheres; 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 ini 
variegated sandstone (buntersandstein). bometimes gem- 
salt appears to oscillate between variegated sandstone and 
muschelkalk. . i r. a t 
I made two excursions on the peninsula ot Araya. In 
the first, I was inclined to consider the muriatiferous clay 
