in t?ie Province of Granada. 47 



alluvion had been formed on the subjacent trachytic rocks pre- 

 vious to the deposition of the tertiary beds. Analogous facts 

 with respect to other rocks have been lately noticed. 



In some strata of zoophytical yellowish limestone close to the 

 village, Pectens, fragments of ostreae and coralline remains, were 

 observed, but the shells are so broken that few entire ones can 

 be found. 



In ascending the high table-formed hill to the north of San 

 Pedro, over which an unfrequented road leads to the village of 

 Carbonera, similar organic remains were frequently noticed. 

 This elevated hill is entirely composed of yellowish zoophytical 

 freestone, separated into thick horizontal strata, and presents to 

 the Mediterranean a bold escarpment, that terminates in an un- 

 dulating slope of volcanic tuff; Section 10. PI. III. Its length is 

 between two and three, its breadth about one and a half, miles, 

 sloping down on its west side to a hollow, where denudation has 

 uncovered the subjacent trachytic rocks. The area of its flat- 

 shaped summit is barren, rugged, and uncultivated, but covered 

 with esparto and other wild plants. 



The descent on its northern end is rugged and precipitous, un- 

 til, near the base of the hill (See Sect. 11.), the path gets upon 

 the softer material, composed of the volcanic tufa. At the bot- 

 tom of the descent there is a little hollow, or valley of denuda- 

 tion, watered by a small stream, beyond which the road again 

 ascends, and enters upon a lower tertiary tract, intersected by 

 several little dry valleys, which continue to border the coast 

 from this point to La Carbonera. The subjacent trachytic 

 rocks, however, are every now and then observed in the lower 

 parts of this hilly ground. In one of the denudated hollows 

 along which the road passes, inclosed between high sloping es- 

 carpments of tertiary beds, several fallen masses, consisting of 

 alternating strata of semi-opal, or hydrate of silica, and coral- 

 sand were observed, which I was prevented from tracing to their 

 origin in consequence of the lateness of the hour. For the be- 

 nefit of future observers, I must mention that the locality is be- 

 tween the northern end of the high table tract crossed in coming 

 from San Pedro, and a remarkable insulated table-hill, near the 

 coast J called La Mesa de Roldan. 



Two or three miles beyond the locality just alluded to, seve- 



