Bax:a and Alhama. 349 



posed of marl without gypsum, the succeeding ones, in a de- 

 scending order, becoming more argillaceous, and containing some 

 gypsum ; whilst those below, to an unknown depth, are cal- 

 careous, sandy, and abound in that mineral. It also appears 

 that, in the lowest beds penetrated, near the centre of the basin, 

 the gypsiferous marls contain imbedded sulphur in sufficient 

 abundance to be advantageously worked, associated with various 

 organic remains, amongst which the existence of the Cypris 

 seems to warrant the conclusion that the deposite has been 

 lacustrine *. 



( To be continued). 



On Valleys of Elevation, and their Connexion with the Origin 

 ofAciduhus Springs. By M. Fkedeeick Hoffmann f . 



It is well known, that of late years MM. Keferstein, Bischoff, 

 De HofF, De Buch, Brongniart and Boue, have sought the ori- 

 gin of the carbonic acid of acidulous springs in the ancient foci 

 of volcanic activity. M. Hoffmann's memoir is a happy com- 

 bination of this idea with the formation of certain valleys by 

 elevation, and its author connects these phenomena with the 

 mutual crossing of different systems of mountains. 



This memoir tends to prove, that the formation of the val- 

 leys of elevation was accompanied by the eruption of a great 

 quantity of water containing carbonic acid, which had been 

 expelled from the depths of the earth ; and that the springs of 



" It would probably be a difficult question of antiquarian investigation, to 

 trace the origin of these subterranean dwellings, inhabited by a considerable 

 population of the poorer class in various parts of the province of Granada. 

 They may be observed in the outskirts of the cities of Granada, Guadiz, and 

 Baza ; but are most numerous in the villages of Benamaurel, Castillejos, 

 Caniles, and Cullar, where they have been excavated in the marl strata so 

 extensively deposited in this basin, and in those of Benabra, and another, 

 whose name I forget, in the valley of Guadiz. In Benabra, the entire popu- 

 lalion lives in caves ; the church, the curate's house, and the Venta, being 

 the only edifices seen above ground. Many of the argillaceof.s conical hil- 

 locks, which give so singular a character to a small tract of ground in the im. 

 mediate vicinity of Guadiz, and to which allusion has been made before, have 

 been also partially excavated and converted into dwellings,— au aperture at 

 the base of the cone serving for entrance, another higher up as a window, 

 and a third, near its apex, as a chimney. 



t From Journal de Geologic. Par M. Boue, &c. No. II. 



