uous through the whole glen, are seen. They vary in width from ten to sixty feet, and are covered with boulders. The highest one is one thousand two hundred and fifty feet above the present level of the ocean, and the other is two hundred feet lower. These terraces are stratified deposits; they are ascribed to the action of water standing at that level, either a lake or the ocean. Similar shelves at these elevations are found in other valleys of Scotland, in Sweden, and in North America. River terraces present similar phenomena; they occur in valleys of mountainous districts, where the river flowing over the drift in which it cuts its channel, removes the materials to lower levels. The sudden removal of obstacles gives origin to a new terrace. These are represented in Fig. 155. Ancient lakes have also been reduced by successive stages, and formed broad level terraces. 289. Various beds of sand and gravel scattered over the valleys and plains are called ossiferous, because they contain bones of the elephant, hippopotamus, bear, deer, horse and other animals which do not now inhabit the regions where their remains occur; the bones of the elephant and rhinoceros are found in England and in Siberia, where they have not been known to exist within the historic period. These bones are partially petrified by the salts of lime and iron, are harder and heavier than recent bones, but still preserve their bony structure. Many of these ossiferous deposits are local, having been produced by the action of rivers, and the filling up of lakes, but some of them appear to be due to more extensive agencies. 290. Numerous caverns have been found in Europe, America and Australia, containing deposits of loam, river silt and small boulders. These materials were probably introduced during different periods; but the animal remains included in them indicate the drift period as the one during which the largest portion of the deposits accumulated. The bones, which are perfectly preserved in many instances in calcareous incrustations, are chiefly those of races of bears and hyænas which inhabited the caves, together with the remnants of their prey, and occasional fragments of the elephant and rhinoceros. The remains of man, and of animals still living in the vicinity are sometimes found in them. The most remarkable caverns, on account of their organic contents, are Kirkdale Cave near York in England, and the Cave of Gailenreuth in Germany. 291. The Kirkdale Cave, which Dr. Buckland has very accurately described in his "Reliquiæ Diluvianæ," is situated about twenty-five miles northeast of York, above the northern edge of the great vale of Pickering, and thirty feet above its waters. conformable to the plane of stratification of the coralline In some parts the cave is three oolite in which it occurs. Its floor is level and nearly or four feet high, and roofed, as well as floored, by the level beds of this rock; in other parts its height was augmented by open fissures, which communicate through the roof, and allow a man to stand erect. The breadth varies from four or five feet to a mere passage; at the outlet or mouth against the valley was a wide expansion or ante-chamber, in which a large proportion of the greater bones, as of the ox, rhi noceros, &c., were found. This mouth was choked with stones, bones and earth, so that the cave was discovered by opening upon its side in a stone quarry. On entering the cave, the roof and sides were found incrusted with stalactites, and a general sheet of stalagmite, rising irregularly into bosses, lay beneath the feet. This being broken through, yellowish mud was found about a foot in thickness, fine and loamy toward the opening, coarser and more sandy in the interior. In this loam chiefly, at all depths, from the surface down to the rock, in the midst of the stalagmitic upper crust, and as Dr. Buckland expresses it, "sticking through it like the legs of pigeons through a pie-crust," lay multitudes of bones of the following animals: Carnivora-hyæna, tiger, bear, wolf, fox, weasel. horse. Ruminantia--ox, three species of stag. The hyæna's bones and teeth were very numerous— probably two or three hundred individuals had left their bodies in this cave; remains of the ox were very abundant; the elephants' teeth were mostly of very young animals; teeth of the hippopotamus and rhinoceros were scarce; those of water rats very abundant. The bones were almost all broken by simple fracture, but in such a manner as to indicate the action of hyænas' teeth, and to resemble the appearance of recent bones broken and gnawed by the living Cape hyæna. They were distributed as in a "dogkennel," having clearly been much disturbed, so that elephants, oxen, deer, water-rats, &c., were indiscriminately mixed; and large bones were found in the largest part of the cavern. The teeth of hyænas were found in the jaws, of every age, from the milk tooth of the young animal to the old grinders worn to the stump; some of the bones were polished in a peculiar manner, as if by the trampling of animals." 292. The most remarkable ossiferous cavern of Germany is that of Gailenreuth, which lies upon the left bank of the Wiesent. The entrance, which is about seven feet high, is in the face of a perpendicular rock, and leads to a series of chambers from fifteen to twenty feet high and several hundred feet in extent, terminated by a deep chasm, which, however, has not escaped the ravages of visitors. This cavern is perfectly dark, and the icicles, or pillars of stalactite, reflected by the torches which it is necessary to use, present a highly picturesque and striking effect. The floor is literally paved with bones and fossil teeth; and the pillars of stalactite also contain osseous remains. Loose animal earth, abounding in bones, forms in some parts a layer ten feet in thickness. A graphic description of this cave was published by M. Esper, more than sixty years ago; at that period some of the innermost recesses contained wagon loads of bones and teeth; some imbedded in the rock, and others in the loose earth. The bones in general are scattered and broken but not rolled; they are lighter and less solid than recent bones, and are often incrusted with stalactite. Cuvier, who enjoyed the opportunity of examining a very large collection of bones from Gailenreuth, was enabled to determine that at least three-fourths of the osseous contents of the caverns belonged to some species of bear; and the remaining portion to hyanas, tigers, wolves, foxes, gluttons, weasels and other small carnivora. By the bones which were referable to the bear, he established three extinct species of that genus, the largest of which is called the Ursus spelæus. The hyæna was allied to the spotted hyæna of the Cape, but differed in the form of its teeth and head. Bones of the elephant and rhinoceros are also said to have been discovered, together with those of exist ing animals, and fragments of sepulchral urns of high antiquity."* 293. The phenomena of ossiferous caverns lead to the conclusion that they were the dens of ravenous animals; that the carcasses of large animals were drifted into them; and that men have used them as places of abode or sepulture. Fragments of bones, mingled with clay, pebbles, shells, etc., cemented together with the carbonates of lime and iron, are frequently found filling fissures in the rocks. Such accumulations are called osseous breccia; they are very abundant in the vicinity of the Mediterranean sea; the rock of Gibraltar yields fine specimens. The bones of the breccia are referable to both extinct and recent species. The bone breccia of Australia has the same ochreous color as that in Europe has; its bones are all referable to marsupial animals, as the kangaroo, wombat, dasyurus, &c. 294. The fossils of this period are very numerous and various; shells, both marine and fresh-water, are found in great quantities beneath beds of gravel and boulders, and especially in beds of marl under the muck-decaying vegetable matter-of ponds and swamps. The long clam, Mya arenaria, and the common oyster, Ostrea borealis, marine shellfish, are found in the deposits of this period far inland, and a very large majority of the shells belong to species inhabiting the ocean of the present day. The immense accumulations of these shells, constituting layers many feet deep, indicate the lapse of a long period of time. Infusoria abounded at this period; the silicious marl beneath peat swamps is almost entirely made up of these fossil skeletons. 295. At this period the most gigantic of the existing * Mantell's Wonders of Geology, p. 169. |