Oeoloeical Socl~TY. [March 8, 2. ~T the Fossil CONTENTS
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Downloaded from http://jgslegacy.lyellcollection.org/ at Monash University on July 3, 2016 364 PROC~.EDI~aSOF TH~ OEOLOeICALSOCl~TY. [March 8, 2. ~t the FossIL CONTENTS Of t~te GENISTA CAVE, GIBRALTAR. By G. BusK, Esq., F.R.S., F.G.S., and the late HuQ~ FALCONER, M.D., V.P.R.S., For. Sec. G.S. [In a Letter to His Excellency General Sir W. J. Codrington, K.C.B., &c. &c. Governor of Gibraltar.] (Communicated by the Secretary of State for War.) THe. circumstances which led to our visit to Gibraltar, and the objects we have had in view, are so well known to Your Excellency that it is unnecessary on our part to do more than refer to one or two incidents in the early history of the cave. When the interesting objects contained in the upper chambers of the "Genista" cave on Windmill Hill were brought to light by Capt. Brome, Your Excellency addressed a letter to the Secretary- at-War, giving a preliminary report on the results; that communi- cation was forwarded from the War Office to the President of the Geological Society of London, with a request for an opinion as to the importance in the interest of science of following up the explo- ration, and for suggestions as to the manner in which it could be best conducted. The reply led to the sanction of the Secretary-at-War for the further exploration of the cavern by means of the labour of the military prisoners, under the able superintendence of Capt. Brome ; and, to pass over minor incidents well known to Your Ex- cellency, the objects discovered were forwarded to us in London for identification and scientific examination. Having devoted several months to the study of the cave-col- lections successively transmitted to us, which were so carefully classified, by means of distinctive marks, by Capt. Brome, the Governor of the Military Prison, as to place the main facts clearly: before us, we were so strongly impressed with their importance that we determined, on Your Excelleney's invitation, to visit Gibraltar and examine the general condition of the cave on the spot; for the discoveries in the Windmill Hill cave have not only yielded unexpected results regarding the former state and the ancient animal population of the rock itself, but they further point to a land connexion between the southern part of the Iberian penin- sula and the African continent at no very remote geological epoch. Capt. Brome's Report, dated 21st August, 1863, with the plan and section which accompany it, so clearly explains the nature of the Windmill Hill cave, that it is unnecessary for us to enter on the present occasion into any detailed description of it. The rock abounds in caves, which are of two classes. 1st. Seaboard caves at various heights above the level of the sea and horizontally excavated in the ancient cliffs by the waves. 2nd. Inland caves descending from the surface and in connexion with great vertical fissures by which the mass of the rock has been rent at remote epochs during disturbances caused by violent acts of upheavement, like the well- known cavern of St. Michael. The " Genista" cave of Windmill Hill belongs to the second class ; it forms part of a great perpendi- cular fissure, which, by the vigorous measures adopted by Capt. Downloaded from http://jgslegacy.lyellcollection.org/ at Monash University on July 3, 2016 1865.] RVSX A~1) rA~O~m~---~I~LTAR cAvp,s. 365 Brome, has either been excavated or traced downwards to a depth of upwards of 200 feet below the level of the plateau of Windmill Hill. It was full of the fossil remains of quadrupeds and birds, of the former of which some are now wholly extinct, others extinct in Europe and repelled to distant regions of the African continent, others either now living on the rock or in the adjoining Spanish peninsula. The following is a list of the species which we have at present identified :-- Pachydermata. Rhinoceros Etruscus (?). Extinct. Rhinoceros leptorhinus (syn. R. megarhinus). Extinct, abundant. Equus. Young animals only, species undetermined. Sus priscus (?). Extinct. Sns scrofa. Living. Ruminants. Cervus elaphus, vat. barbarus. Fossil remains abundant. Cervus dama, or a nearly allied form. Abundant. Bos. A large form, equalling the Aurochs in size, remains few and imperfect, species undetermined. Bos taurus. Abundant in the upper chamber. Capra hircus (?). In the upper chamber. Capra 2]~goceros, form A.; Capra ~goceros, form B. Two forms of/bex, probably extinct but in vast abundance throughout the fissure. Rodents. Lepus timidus. Rare. Lepus cunieulns. Very abundant at all depths. Mus rattus. Garnivora. Felis leopardus. Felis pardina. FelLs serval. Hyaena brunnea. Now repelled in the living state to Southern Africa. Canis vulpes. Ursus, sp. ~'ot the Cave Bear, form undetermined. Dell~hinidce. Phocsena eommunis. JBirds. Remains numerous, genera and species undetermined. Tortoise. Rare, species undetermined. F/sh. Remains numerous in the upper chamber. Apart from the still immature state of the investigations, it would be quite beyond the limits within which we are restricted in this communication for us to enter in detail upon the conclusions to which the data furnished by the fossil remains lead ; we shall there- fore confine ourselves to a few of the more important general points. The rock is now bared of natural forest-trees, and destitute of wild animals, with the exception of the hare, rabbit, fox, badger, and a few magot monkeys, the last in all probability the descendants vor XXL--rA~T. I. 2 C Downloaded from http://jgslegacy.lyellcollection.org/ at Monash University on July 3, 2016 366 Pnoc~I~as oF rue (~EoLo(~ICXL socI•'rY. [March 8, of introduced animals. The fossil remains of the "Genista" cave establish be3.ond question that the rock was formerly either peopled by, or the occasional resort of, large quadrupeds like the elephant, rhinoceros, aurochs, deer, ibex, wild horse, boar, &c., which were preyed upon by hyenas, leopards, African lynx, and serval: that the remains were transported by any violent diluvial agency from a distance is opposed to all the evidence of the case. The manner in which they were introduced into the Windmill Hill cave we believe to have been thus :--The surface of the rock and its level in relation to the sea were formerly different from what we now see. The wild animals above enumerated, during a long series of ages, lived and died upon the rock. Their bones lay scattered about the surface, and in the vast majority of instances crumbled into dust, and disappeared under the influence of exposure to the sun and other atmospheric agencies, as constantly happens lmder similar circum- stances at the present day. But a certain proportion of them were strewed in hollows along the lines of natural drainage when heavy rains fell; the latter, for the time converted into torrents, swept the bones, with mud, shells, and other surface-materials, into the fissures that intercepted their course; there the extraneous objects were arrested by the irregularities of the passages, and subsequently soli- dified into a conglomerate mass by long-continued calcareous infil- tration. That elephants frequented the rock is proved by a valuable specimen of the molar tooth of an extinct species, which we have ascertained to be Elephas e~ntiquus, discovered by Mr. Smith, of Jordan Hill, in a sea-beach on Europa Point. That the hyenas were dwellers upon the rock is also established by the fact that, in addition to numerous bones, we have discovered a considerable quan- tity of coprolites of Hyce.~a brunnea among the "Genista" cave relics. Some of the species must have peopled the rock in vast numbers. We infer, upon a rough estimate, that we have passed through our hands bones derived from at least two or three hundred individuals of ibex swept into the Windmill Hill fissure; in no instance have we observed fossil bones attributable to one complete skeleton of any one of the larger mammalia. That the rock now so denuded of arboreal vegetation was then partially clothed with trees and shrubs, as the corresponding lime- stone mountains on the opposite side of the straits are at present, is so legitimate an inference as hardly to be open to rational doubt. It is now a pinch to find sufficient food at the end of the hot season for the flocks of goats which are reared on the promontory ; while it is a matter of absolute difficulty to find fodder at all for the few cows that are kept by some of the officers of the garrison. When elephanth, rhinoceros, wild oxen, horse, boar, deer, &c., &e. either peopled or resorted to the rock in considerable numbers there must have been abundant trees and more or less constant green food for them. Bare exposed masses of rock get intensely heated by a southern sun, they repel moisture by being thus heated, and raise the mean temperature of the locality by radiation; while, on the contrary, a clothing of trees and of fruticose vegetation both Downloaded from http://jgslegacy.lyellcollection.org/ at Monash University on July 3, 2016 1865.1] nvsK .~'D ~X~COX~---aI~a.~TXR e.~VES. 367 tempers the heat, attracts moisture, and greatly increases the fall of rain. We are aware that Your Excellency's attention has been directed to planting-operations on the " rock." :Numerous and re- peated failures must be looked for at the commencement; but the facts above mentioned would indicate that success may ultimately be attained, with much benefit to the station. The next prominent point in the case is the character of the extinct fauna of Gibraltar regarded ~ a group.