GEOGNOSY AND GEOLOGY. 189 
and Weser. These constitute the so-called erratic phenomena. Erratic 
boulders are often of considerable size, and are generally derived from more 
northern mountain regions. The petrographical character of the boulder 
sometimes enables us to decide with tolerable accuracy as to its native 
locality. In the south of Europe such blocks sometimes occur as the one 
shown in pl. 46, fig. 19, from forty to sixty feet in diameter, and found near 
Monthey in the Pays de Vaud. At this period masses of still more limited 
occurrence were formed, as a fresh water limestone, calcareous tufa, or 
older travertine, containing hornstone, jasper, and flint. In it are found 
Lymnea, Planorbis, Paludina, Helix, Pupa, Cyclostoma, &c. Volcanic 
tufas and conglomerates are sometimes associated. Mammalia are 
represented by proboscidian pachyderms, oxen, and deer. To this same 
period belong the calcareous conglomerates and osseous breccias, often 
found elevated at a considerably high level on the southern coast of Spain ; 
also, the calcaire mediterranien of Nizza, the clefts filled with shelly 
conglomerate, and the bone deposits of caverns. The latter are extensively 
distributed, and occur principally in cavities of limestone rocks, which have 
been shattered or fissured in some way or other, and the fissures excavated 
by the action of water or corrosive gases. At the bottom of the caverns 
there generally occur blocks and bones of various kinds, often cemented by 
a ferruginous mud and sand, the whole mass covered by stalagmite, 
stalactites depending from the top and sides. The origin of stalagmites 
and stalactites has already been explained. The bones are generally 
broken and crushed, especially the long bones of the extremities. Many in 
certain localities exhibit traces of carnivorous teeth, as of hyenas, wolves, 
&c. Some are rounded by the action of water. The cavities of the larger 
bones will frequently be found to contain fragments of bones belonging to 
smaller animals. Bone caves generally occur in series of hollows, connected 
by narrow passages. 
Various theories have been propounded as to the manner in which these 
deposits have been produced, but no single one, nor indeed a combination 
of all, is sufficient to. account for the phenomena which are sometimes 
presented. Some have been introduced, no doubt, by the agency of 
rapacious beasts which made dens of the caverns. Thus, in the celebrated 
cave of Kirkdale in England, unmistakable evidence of this is presented in 
the fact, that with the bones are associated, in vast quantities, the excrements 
of hyenas, and the bones themselves are broken and shattered in precisely 
the same manner as if they had been subjected to the action of hyenas of 
the present day. The association of water-worn sticks, pebbles, &c., with 
the bones, also shows that to the action of water may be ascribed a 
considerable share in the phenomena. Again, many caves are connected 
with sink-holes or katavothra, funnel-shaped depressions in limestone regions, 
into which water pours from a greater or less extent of country. Such pits 
being thickly overgrown with bushes, naturally afford a secure harbor for 
predaceous animals, which drag their victims into these localities for 
security. The accumulating and. broken bones are carried down into the 
cavity at the bottom of the pit by the next heavy rain, and thus either 
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