34 



CAVE 



underground galleries owe their inception entirely 

 to the chemical action of water seeking its way 

 downwards from the surface, and following the 

 lines of natural division-planes in the rocks, it is 

 obvious that caves will be of most common occur- 

 rence in regions where the rocks yield most readily 

 to such chemical action. Among the more soluble 

 rocks are rock-salt and gypsum, but these are only 

 locally developed in such quantities as to give> rise 

 on their removal to underground cavities of any 

 extent. Calcareous rocks, more especially limestone, 

 have not only an almost world-wide distribution, 

 but they also occur in greater mass than either 

 gypsum or rock-salt, and hence, although not so 

 readily acted upon by water as the latter two, it is 

 in limestones that nearly all the most renowned 

 caves and subterranean galleries appear. 



Many caverns have a calcareous incrustation 

 lining their interior. Sometimes this deposit is 

 pure white ; it is, however, more generally coloured 

 by the impurities which the water, percolating 

 downwards from the surface, has taken up from the 

 superincumbent rocks. To the incrustations which 

 are suspended from the roof like icicles, the name 

 stalactites is given, while those rising from the floor 

 are called stalagmites. The origin of these is as 

 follows : Water which has percolated down from 

 the surface always contains a certain proportion of 

 carbonic acid it is acidulated water the acid 

 being derived from the atmosphere and the decaying 

 organic matter of the soil, &c. Water thus charged 

 with carbonic acid has the power of dissolving 

 limestone i.e. it takes up a certain proportion 

 of carbonate of lime and converts it into the soluble 

 bicarbonate. Arrived at the roof of a cave it oozes 

 out and is there subject to evaporation, the excess 

 of carbonic acid is parted with, and a thin pellicle 

 of carbonate of lime is deposited as an incrustation. 

 When the drops fall to the floor they are subject 

 there in the same way to evaporation, and are thus 

 compelled to give up the remainder of the cal- 

 careous matter held in solution. By this constant 

 dropping and falling, icicle-like pendants grow 

 downwards from the roof, while sheets, bosses, and 

 domes gradually accumulate upon the floor until, 

 not infrequently, these stalagmites come at last to 

 unite with the gradually lengthening stalactites, 

 and so to form, as it were, pillars which look as if 

 they had been placed to support the roof. See the 

 articles on ADELSBERG, AGTELEK, KENT'S CAV- 

 ERN, MAMMOTH CAVE, &c. 



BONE-CAVES. Caves are of interest to geologists 

 not only because they testify to the potency of the 

 chemical and mechanical action of underground 

 water, but on account of the remarkable evidence 

 they have yielded as to the contemporaneity of man 

 with many extinct and no longer indigenous mam- 

 mals. This evidence is furnished by the accum- 

 ulations which so frequently cover the floors of 

 caverns to a greater or less depth. The accumula- 

 tions in question consist partly of clay, sand, gravel, 

 and shingle, and partly of red earth and sheets of 

 stalagmite. Some of these are doubtless the 

 alluvial detritus carried forward by underground 

 streams. This detritus often consists largely of 

 angular, subangular, and water- worn fragments of 

 limestone, which have doubtless been derived from 

 the roof and walls of the underground galleries, 

 but not infrequently the presence of other kinds 

 of rock-fragments shows that no inconsiderable 

 amount of material has been introduced from the 

 outside by the streams as they plunged into their 

 subterranean courses. Much debris also may have 

 been swept in by heavy rain or flooded torrents 

 washing down through the sinks and swallow-holes 

 that so frequently pierce the roofs of subterranean 

 watercourses. These sinks often become pitfalls to 

 unfortunate cattle in our own day, and in former 



times many animals may have been entrapped in: 

 the same way for broken and rubbed bones ofteni 

 occur, sometimes very abundantly, in the old torren- 

 tial accumulations of deserted subterranean water- 

 courses. When the galleries ceased to be traversed 

 by streams, stalagmitic accretions would then begin, 

 to accumulate over the shingle and debris beds. 

 In course of time many of these subterranean, 

 hollows, becoming more or less accessible from the 

 outside, were occupied by carnivorous animals, 

 who carried thither their prey, and thus by and 

 by accumulations of bones were formed, which 

 tne drip of water from above gradually inclosed 

 in calcareous matter, and eventually covered 

 up under a sheet of stalagmite. Now and again 

 the caves were occupied for shorter or longer 

 periods by man his presence being still evidenced 

 by his implements and weapons, by charred and 

 split bones, &c. , and occasionally by portions of his 

 own skeleton and these relics, in like manner,, 

 subsequently became sealed up in a more or less 

 thick accumulation of stalagmite. Some of these 

 bone-caves contain the record of many physical 

 changes. Thus, we have evidence to show that 

 after having been the haunt of wild beasts or the 

 abode of man for some indefinite but often pro- 

 longed period, the cave again gave passage to a flow 

 of water, and deposits of loam, clay, or gravel, &c. 

 were laid down upon the stalagmitic pavement and 

 bone-breccia. Or, as in some cases, the stalag- 

 mite, together with bones covered by and inclosed 

 within it, was broken up and partially or wholly 

 removed. Then, at a subsequent date the stream 

 once more deserted its channel, while carnivores or 

 man again returned, and newer heaps of bones and 

 stalagmite accumulated. Commingled with these 

 stalagmites of the bone-caves there is almost 

 always more or less of a reddish earth or clay, 

 which is the insoluble residue of the limestone from 

 the dissolution of which the stalactites and stalag- 

 mites are formed. Some of the more remarkable 

 bone-caves which have yielded testimony as to the 

 contemporaneity of man with extinct mammalia,, 

 are Kent's Cavern (q.v) and Brixhani Cave in Eng- 

 land, the caves in the valley of the Lesse in Belgium, 

 the caves of Perigord and the Pyrenees in France, 

 and the Kesserloch near Thaingen in Switzerland. 

 Bone-caves containing the remains of post-tertiary 

 mammals are rare in North America ; those of Brazil 

 have many bones of large rodents and edentates. 

 For caves at Wick, in Scotland, still occupied by 

 tinkers, see Sir Arthur Mitchell, The Past in the 

 Present (1880). For accounts of special caves, see 

 the British Association Reports ( For Kent's Cav- 

 ern) and the Philosophical Transactions (1822-73). 

 For general descriptions, see Buckland's Reliquiae 

 Diluviance, Dupont's L'Homme pendant les Ages 

 de la Pierre, Lartet's and Christy's Reliquice Atjid- 

 tanicce, Lubbock's Prehistoric Times, Dawkins' 

 Cave-hunting, J. Geikie's Prehistoric Europe. For 

 further information as to the European cave- 

 dwellers of prehistoric times, see MAN, FLINT 

 IMPLEMENTS, PLEISTOCENE SYSTEM. 



ARTIFICIAL CAVES. The primitive inhabitants 

 of most civilised countries and many primitive 

 tribes at the present day have been troglodytes or 

 cave-dwellers. In many countries where natural 

 caves are either of rare occurrence or do not occur 

 at all, certain rock- exposures have been artifici- 

 ally excavated, and occupied either permanently 

 as dwelling-places or occasionally as retreats in 

 times of danger, while others have been used as 

 cells, hermitages, or burial-places. Such caves are 

 not uncommon in the cliffs of Scottish river ravines, 

 as at Hawthornden near Edinburgh, and in the 

 valley of the Jed, Roxburghshire. Caves of this 

 kind occur usually in rocks that are readily dug 

 into, such as soft sandstone. Now and again,. 



