OF GIBRALTAR. 15 



it is extremely difficult to collect the bones of any dis- 

 tinct species. No human bones have been discovered, 

 although works of art are occasionally found in the 

 more recent formation. A cannon ball is also said to 

 have been surrounded by a breccious cement. 



" Over the stalactitic stratum which has been de- 

 scribed/' continue the authors we have just quoted, 

 " there is a more recent limestone breccia," (testaceous 

 conglomerate of Mr. M c Gregor), which lies on the 

 surface of the ground here and there, rent into 

 separate blocks of rocks. It consists of a grayish 

 white or gray limestone, the detritus of calcined 

 shells, very few fragments of bones, and a rather 

 reddish, granular mortar-like cement ; the pieces of 

 limestone are here smaller from half a line to six 

 lines in diameter, and instead of the above-mentioned 

 grains of quartz which are entirely wanting, there are 

 whitish, pearl-like globules of stalactitic limestone, 

 resembling the Carlsbed pea-stones. The calcined 

 shells are far more numerous here, and form in a 

 manner thin strata in the stone : no entire shells, 

 indeed, are to be found among them ; they seem, 

 however, from their thickness and breadth to belong 

 to the common oyster; others, from their dotted 

 edge and convexity, perhaps to a cockle (Cardium) ; 

 that is to say, to marine Conchylia." The whole of 

 this formation does not appear to be more than two 

 hundred feet above the limestone rock, and fresh 

 formations appear still to be going on in the neigh- 

 bourhood of the sea. 



An importance is attached to this remarkable 

 breccia formation of Gibraltar, from the circumstance 



