§ 43. THE ROCK OF GIBRALTAR. 



187 



feet. It is in great part composed of strata of compact, 

 bluish-grey marble, of the oolitic period, which like most ex- 

 tensive limestone masses is cavernous. The principal cavern, 

 called St. Michael's, contains stalagmites and stalactites, 

 which when polished are of great beauty. The fissures in- 

 tersecting the rock, as well as those in some of the caves, 

 are partially filled up with a calcareous concretion, of a 

 reddish-brown colour, which in some parts is a mere earthy 

 mass, but in others is highly indurated. The bones are com- 

 monly in a broken state, and but seldom water-worn ; and the 

 fragments of limestone with which the fissures abound, are 

 also angular, and have evidently, like the bones, fallen into 

 the crevices at different periods, and been gradually in- 

 crusted and conglomerated by calcareous infiltrations. 

 Snails and other land shells of the existing species of the 

 country often occur impacted in the solid breccia ; and as 

 the stalactitic concretion is constantly going on, some masses 

 contain recent terrestrial shells unmixed with bones. 



The cementing material is very similar in the different 

 localities where the breccia has been observed ; namely, at 

 Cette, Nice, Antibes, &c. in Dalmatia and Sardinia. The 

 animal remains of the breccia are referable to several 

 species, some of which are recent and others probably ex- 

 tinct, of deer, antelope, rabbit, rat, mouse, &c. Bones of 

 birds and of lizards have been discovered at Cette ; and of 

 lemmings,* and of the lagomys^ which now only exists in 

 Siberia : it is but rarely that traces of carnivora are 

 observed.]: 



No one can fail being struck with surprise at the occur- 

 rence of these isolated, yet analogous phenomena, which 



* Lapland marmot. 



f Signifying rat, or tailless hare ; a small animal which forms a link 

 between the hare and the rat. 



% See an interesting memoir in the Geology of the Environs of Nice , 

 by Sir H. De la Beche : Geol. Trans, vol. iii. p. 171. 



