56 me; g. busk on the ancient or 



This brief geological notice will suffice to account for the innumerable caverns and 

 fissures by which the Rock of Gibraltar is penetrated in all parts from its summit to 

 the base, and whence it has occasionally been termed the " Hill of Caves." 



From a general survey of the conditions under which the osseous remains occur, all 

 the phenomena may be explained, as was remarked by Major Imrie, on the supposition 

 that they were washed into the more or less vertical open cavities by the heavy- 

 autumnal floods. In support of this it may also be stated that most of the bones, more 

 especially at the articular surfaces, are sun-cracked, or have that peculiar kind of reti- 

 culated Assuring which arises from exposure to atmospheric agency. Others, again, are 

 simply crushed, the splinters being recemented by a fine, ochreous, crystalline stalagmite. 

 This condition can only be accounted for on the supposition (in the absence of tooth- 

 marks) that the bones had either fallen from a considerable height or, what is more 

 probable, had been broken by the falling upon them of heavy portions of rock after 

 they had become lodged in the fissure. To this mode of introduction must be added 

 the circumstance, now for the first time made known, that in all probability the entire 

 bodies of animals, either before or after death, were occasionally precipitated into the 

 gaping cracks. Instances of this will appear in the sequel. 



With respect to mineral condition, many of the fossil bones are hea\'y, dense, hard, 

 and strongly infiltrated with manganese ; whilst others, though deprived to an equal 

 extent of the animal substance, which is replaced in some measure by carbonate of 

 lime, are perfectly white, easily cut or powdered, and without any trace of manganese^ 

 Notwithstanding the abundant evidence of the existence of the Hysena as a former 

 member of the Rock-fauna, not a single bone has as yet been detected bearing indu- 

 bitable marks of its teeth. The only bones showing marks of gnawing (by Arvicola, 

 or perhaps the Fox) belonged wholly to the upper compartments of the Genista Cave ; 

 and they are either human or of species coexistent with man. 



As regards the amount and nature of its osseous constituents, the breccia differs very 

 much in different parts of the rock and at different elevations. In fissures near the 

 base the breccia contains usually but few bones, being chiefly formed of angular frag- 

 ments of the grey limestone imbedded in the universal ochreous indurated matrix ; in 

 other places the extraneous contents are almost entirely land shells (Helix, BuUrnus 

 decoUatus, &c.) ; whilst in the more elevated and precipitous points of the mountain 

 the narrow fissures are filled with a breccia consisting almost entirely of the bones of 

 birds and other small animals, no doubt conveyed by the Hawks which there find their 

 habitation and breeding-places. 



In most parts the fissures appear to have remained open until they were filled with 



' Small fragments of bone, usually, if not wholly, of Cervus or Ibea;, and deeply carbonized, were met with 

 even in the deepest part of the Genista Cavern. These fragments, probably representing the relics of human 

 repasts, have doubtless found their way through small fissures in the floor or sides of the upper chamber. They 

 are never coated with stalagmite. 



