THE GEOLOGY OE GIBRALTAR. 531 



tion of scarping the cliffs ; and the bone-breccia may still be seen 

 in situ both in the cliff and upon the beach at its base. 



During the accumulation of the limestone-agglomerate it is evi- 

 dent that the promontory of Gibraltar must have extended consider- 

 ably further seawards. This is shown by the fact that the agglo- 

 merate descends below the sea-level. But the whole appearance of 

 the rock indicates a subaerial origin. Had the debris, in its uncon- 

 solidated state, pushed forward into the sea, it seems certain that 

 the waves would have made short work with it, and rearranged its 

 materials into more or less well-marked deposits of shingle, gravel, 

 and sand. But one has only to look at the agglomerate to be assured 

 that, long before the sea began to erode it, it had already become 

 consolidated by infiltration. There can be no doubt, therefore, that 

 the limestone-agglomerate of Buena Vista indicates a former greater 

 extent of land at Gibraltar ; but of course it is quite impossible to 

 say how far the land then stretched out into the Mediterranean. All 

 that the evidence entitles us to affirm is simply this : — That the lime- 

 stone-agglomerate was accumulated under someivhat severe climatic 

 conditions, at a time ivhen the Bock had a wider area of low ground 

 at its base, and when, so far as we know, it ivas not tenanted by land 

 animals. 



After the agglomerate had been long exposed to subaerial in- 

 fluences, it not only became hardened into a solid mass, but was 

 traversed by fissures of erosion, some of which go down through its 

 whole thickness into the underlying limestone. From the position 

 of these fissures, and from the appearance presented by such caves 

 as that of Genista, it is evident that both were in existence before 

 the period of depression when the marine terraces and platforms 

 were eroded. And not only so, but some of the fissures at least had 

 also been choked up with bone-breccia before the great limestone- 

 agglomerate of Buena Yista was brought under the influence of 

 marine erosion. This is certainly the case with the celebrated bone- 

 breccia of Rosia Bay. That fissure could only have been licked out 

 and filled up again with bones, gravel, and earth when the surface 

 of the ground differed greatly from the present. Since the bones 

 and debris were swept into fissures and caves by superficial and en- 

 gulfed torrents, that whole district has been subjected to long-con- 

 tinued marine erosion, by which agglomerate and limestone alike 

 have been carved into platforms, while these terraces in turn have 

 been greatly modified by subsequent subaerial influences. Prom all 

 which it follows that the Rock was in occupation by the Pleistocene 

 Mammalia at a time intermediate between the consolidation of the 

 ancient unfossiliferous agglomerate on the one hand, and the forma- 

 tion of the limestone-terraces and raised beaches on the other. 



Amongst the species obtained in the Genista Cave, and iden- 

 tified by Messrs. Busk and Falconer, there are rhinoceros (Eh. 

 hemitoechus), horse, boar, deer (C. elaphus and C. dama), ibex, 

 bear, wolf, Hyoma crocuta, lion, panther, lynx, serval, &c. 

 At the time this fauna tenanted the Rock it is evident, as Messrs. 

 Busk and Falconer have remarked, that Gibraltar could not 



