348 Colonel Silvertop o?* tJie Lacustrine Basins of 



the secondary limestone* and older rocks-f, stated to form the 

 geographical limits of the basin towards the east. 



All the tract surrounding Caniles, a village situated in the 

 upper part of the Valley of Baza, and about six miles from this 

 city, towards the S. SE., is also formed of horizontal strata of 

 marl, in which I did not observe any imbedded gypsum, nor, 

 as I was informed when there, is it found in the neighbourhood. 

 Intervening between this tract and the eastern flank of the Sierra 

 deBaza;]:, there is much conglomerate, composed, like that along 

 the northern base of this ridge, of fragments of argillaceous 

 schist, greywacke, and transition hmestone, imbedded in a reddish 

 calc-argillaceous cement ; and, towards the east and south, at a 

 few miles from Caniles, gravel is extensively spread over a con- 

 siderable tract, called El Desierto de Jauca. 



Other localities within the area of this basin, not visited by 

 me, present phenomena interesting to the geologist, viz. the 

 brine springs of Vacor, the mineral waters of Casablanca, and 

 the neighbourhood of Zucar, where testaceous remains and a 

 variety of lignites are found. These three little villages are si- 

 tuated to the north of the line of road between Guadiz and Baza. 

 In concluding, I beg to recall your attention to two facts 

 which intimately connect this basin with that which will form 

 the subject of my next communication. The jirst is the 

 superposition of the compact limestone with paludinae to the 

 gypsiferous marls ; the second, the superposition of the latter to 

 the secondary nummulite limestone. I shall, however, show, in 

 the description of the basin of Alhama, the existence of other 

 intermediate strata between the gypsiferous marls and the num- 

 mulite limestone. 



The valleys of denudation, along which the rivulets of Gua- 

 diz, Baza, the Guardal, and some minor streams now flow, as 

 well as the numerous dry hollows which diversify the surface, 

 afford many opportunities of observing sections of the gypsife- 

 rous marl. That near Baza proves that the upper beds, or those 

 immediately under the compact paludina limestone, are com- 



■ Sierra de Maria. f Greywacke and argillaceous schists. 



X A patch of snow still remained, on tlie 28th of May, near the summit of 

 Sierra de Baza, opposite Caniles. A barometrical observation 1 made at this 

 point gives an altitude of 4856 feet above the level of the Mediterranean. 



