Baza and Alhama. 87 



west, and until the sun was much above the horizon, the cold 

 was considerable. From this circumstance, and the continual 

 ascent from Murvitdro, upon the eastern mediterranean coast of 

 Spain, to a point in the tract Z, called El Puerto, about three 

 leagues beyond Segorve, on the line of road from Valencia to 

 Teruel, it appears evident that this lacustrine deposite has taken 

 place at a very considerable elevation above tlie level of the sea ; 

 and the same remark may be made with respect to those in the 

 vicinity of Baza and Alhama, as well as the compact limestone 

 observed near La Gineta and Ocana in La Mancha : nor shall- 

 I be far from the truth in calculating the surface of the superior 

 beds in the respective basins of Teruel, Alhama, and Baza, at 

 about 2000 feet above the level of the sea. The ground near 

 La Gineta and Ocana is still more elevated. 



It has been stated, that within the area of each of the lacus- 

 trine basins near Baza and Alhama, springs or streams impreg- 

 nated with muriate of soda existed, the former being called Las 

 Salinas de Vacor, the latter Las Salinas de Malil. Contiguous 

 to the gypsum tract near Aranjuez, which, together with the 

 superjacent compact limestone seen at Ocana, are, from identity 

 in composition and geological position, presumed to be lacus- 

 trine like the same two formations near Baza and Alhama, sul- 

 phate of soda has been discovered in sufficient abundance to be 

 employed advantageously in the arts * ; and a couple of miles 

 higher up the same bank of the Tagus, muriate of soda, in the 

 form of rock-salt, is met with at Villa Rubia, a village whose 

 name is well known to mineralogists as the locality of the glau- 

 berite. 



The analogies thus pointed out, and the real geological rela- 

 tions of these doposites of salt, I leave to future observers, who 

 may perhaps discover that the high elevation of the plaieau of 

 La Mancha is partly owing to a thick and extensive formation 

 of tertiary beds. 



• This sulphate of soda was first discovered by a Spanish gentleman of the 

 name of Rodas, who, in consequence, erected a large manufactory at Aran- 

 juez, where it is converted into a carbonate, and sold to soap-makers as a 

 substitute for barilla. 



