260 



and friable ; but it encloses more solid masses of 

 a blackish brown, of a schistose, and sometimes 

 conchoidal fracture. These fragments, from 

 six to eight inches long, have an angular form. 

 When they are very small, they give the clay a 

 porphyroidal appearance. We find disseminat- 

 ed in it, as we have already observed, either in 

 nests, or in small veins, selenite, and sometimes, 

 though seldom, fibrous gypsum. It is remark- 

 able enough, that this stratum of clay, as well 

 as the banks of pure gem salt and the salzthon 

 in Europe, scarcely ever contain shells, while 

 the rocks adjacent offer them in great abun- 

 dance. 



Although the muriat of soda is not found 

 visible to the eye in the clay of Araya, we can- 

 not doubt of it's existence. It discovers itself 

 in large crystals, if we sprinkle the mass with 

 rain water, and expose it to the Sun. The mere 

 to the east of the castle of San Jago exhibits all 

 the phenomena, which have been observed in the 

 salt lakes of Siberia, described by Lepechin, 

 Gmelin, and Pallas. This mere receives how- 

 ever only the rain waters, which filter through 

 the banks of clay, and unite at the lowest point 

 of the peninsula. While the mere served as a 

 salt-work to the Spaniards and the Dutch, it did 

 not communicate v/ith the sea ; at present this 

 communication has been interrupted anew, by 

 placing faggots at the place where the waters of 



