Bonecaves

Bone-caves are caverns, occurring mostly in limestone, from which bones of animals, the more interesting of which are no longer living in the same area, have been obtained. The caverns are the result of the solvent action of water charged with carbon-dioxide from the air and from vegetable mould, acting along joints (q.v.) or other fissures in the limestone. Their roofs often fall in at some points, forming natural pitfalls into which numerous animals may have fallen. From a cavity 25 feet by 18, at Castleton, Derbyshire, 6,800 bones of bison, reindeer, bear, wolf, fox, and hare were obtained. In other cases bones have been washed into the cave with silt carried by a flood. Many caverns have, or had, mouths opening on the sloping sides of valleys, where the streams, which sometimes issue from them, run into some river. Here animals may find an entrance. Bone-caves are divided into fissure-caverns, into which bones have been washed; dens, into which carnivore, such as the lion, bear, and in England especially the hyaena, in Ireland the wolf, and at the present day the fox, have dragged the carcases of their prey; and shelter-sheds, into which old or infirm animals retire to die. In dens the bones often bear toothmarks, and hyaena-dens contain large quantities of album graecum, the dung of that animal. In Syria at the present day nomad hunters drive out the hyaenas and temporarily occupy their dens, and so it seems to have been in prehistoric times in Britain. In some cases rude chipped flint implements (palaeolithic) are found in the lowest deposits, and others more highly finished and polished (neolithic), with bone needles and fish-hooks, and even relics of the bronze and iron ages, in higher layers. The bones and other relics are either on the dry floor of the cave, or in cave-earth, a red clay residue from the dissolved limestone, or a fine silt washed in through fissures, or in stalagmite (q.v.), the carbonate of lime left by evaporation on the floor, often several feet thick, or in bone-breccia, mixed with fallen fragments of the roof and cemented by stalagmite. Human bones are but rarely met with among the oldest deposits, but his implements show man to have lived in Britain with Machairodus, the sabre-toothed tiger, the mammoth elephant, the great Irish deer, the grizzly bear, and the hyaena. Among the most important bone-caves in Britain are the systematically explored Kent's-Hole, Torquay, and those at Cae Gwyn, North Wales, the deposits in which are supposed to be partly Pre-glacial. In those of the Dordogne and elsewhere in the south of France, numerous reindeer bones are found with those of man, and incised representations on bone and ivory of the reindeer and the mammoth. There is evidence in South Devon and elsewhere of considerable changes in physical geography, such as the deepening of river-channels, since the caves were first inhabited.