52 Brigadier Silvertop's Sketch of the Tertiary Formation 



former town. (See Section 16. PI. I. shewing the fissure or sort 

 of narrow dry valley, bounded by primary and transition moun- 

 tains, between Vera and Lorca). 



This argillaceous, marly, sandy deposit near Vera, in which 

 ^he sandstone beds dip towards the north-west, underlies, accord- 

 ing to fair geological deduction, the masses of conglomerate beds 

 of micaceous sandy loam, containing tertiary organic remains in 

 the higher part of the fissure or valley of the Almanzora just 

 alluded to; and although the only zoological evidence of the 

 epoch to which the former belongs, consists in the teeth of 

 sharks found in an argillaceous mass near this town, I am in- 

 clined to refer it to the earlier part of the Spanish tertiary pe- 

 riod, for these teeth are identical with those found in the lower 

 tertiary bed or group; 1, at Alaurin near Malaga, and the tes- 

 taceous remains found at Uracal, Comartin and Searon, are si- 

 milar to those met with in the upper tertiary bed or group ; 

 2, at the same locality. 



In the group of low mammelonated hills of pitch stone conti- 

 guous to the road from La Garrucha to Vera, and to which the 

 disturbance in the sandstone strata has been attributed^ many 

 instances are observed of an earthy whitish marlstone, changed 

 into a porcelanic compact limestone of a brown and lavender co- 

 lour, in alternating stripes or bands *, when in contact with the 

 pitchstone. Other instances are seen where no change has taken 

 place, but in different parts of the group pieces of whitish marl- 

 stone were observed interlocated in a mass of black pitchstone, 

 in which several almond-shaped nodules of different sizes, but 

 never bigger than an ordinary hen's egg, of crystallized carbo- 

 nate of lime, are also embedded. The pitchstone is of a dark 

 blackish colour, without any appearance of stratification, but se- 

 parated by thin fissures or lines into fragments and polyhedral 

 blocks : its fracture compact, somewhat splintery and inclined to 

 the conchoidal, brittle in small, but tenacious and hard in large 

 pieces. 



This group occupies an area of about one mile and a half in 

 length, and about one mile in breadth, and seems to form a link 



* Analogous facts with respect to limestone, when in contact with pyroge- 

 nic rocks, will be mentioned (at Cabero Negro, Monteagudo, and Orihuela), 

 in a memoir upon the geological structure of the province of Murcia. 



