again, as it were, together with all its contents, by the deposition of a solid crust of stalagmite — an operation requiring a very great length of time to effect — the Reindeer (Ccrvus Tanmdiis) was indigenous ta this country, as is proved by the occurrence of an antler of that animal which was found lying upon, and partly imbedded in, the stalagmite forming the roof or uppermost, that is, the latest formed, of the cave-deposits. Lastly, we learn that, at the time the cave was formed, and while the land was inhabited by man, that part of the country was lower by ninety-five feet than it is now; and. that this elevation has probably been produced so slowly and so gradually, as to have been imperceptible during the time it was taking place, which extended over a vast interval of time, perhaps over thousands of years.

Perhaps it may not be out of place here to describe the mode of formation of bone-caves generally, and the causes which have produced the appearances these now present.

Caves in limestone rocks have two principal phases — one of formation, and one of filling up. So long as the water which enters the cavities in the course of formation, and carries off some of the calcareous matter in solution, can find an easy exit, the cavity is continually enlarged; but whtn, from various causes, the water only enters in small quantities, and does jiot escape, or only finds its way out slowly, and with difficulty, the lime, instead of being removed, is rc-deposited on the walls, roof, sides, and floor of 'the cavity, in the form of stalactites and stalagmite, and the work of rc-f-Uing with solid carbonate of lime then takes place.

Encouraged by the Brixham discoveries, a congress of French and English geologists met at Amiens, in order to consider certain evidence, on which it was sought to establish as a fact that man and the Mammoth were formerly contemporaries.

The valley of the Somme, between Abbeville and Amiens, is-occupied by beds of peat, some twenty or thirty feet deep, resting on a thin bed of clay which covers other beds, of sand and gravel, ar.d itself rests on white Chalk with flints. Bordering the valley, some hills rise with a gentle slope to a height of 200 or 300 feet, and here and there, on their summits, are patches of Tertiary sand and clay, with fossils, and again more extensive layers of loam. The inference from this geological structure is that the river, originally flowing through the Tertiary formation, gradually cut its way through the various strata down to its present level. From the depth of the peat, its lower part lies below the sea-level, and it is supposed that a depression of the region has occurred at some period: again, in land

lying quite low on the Abbeville side of the valley, but above the tidal level, marine shells occur, which indicate an elevation of the region; again, about loo feet above the valley, on the right bank of the river, and on a sloping surface, is the Moulin-Quignon, where shallow pits exhibit a floor of chalk covered by gravel and sand, accompanied by gravel and marly chalk and flints more or less worn, well-rounded Tertiary flints and pebbles, and fragments of Tertiary sandstone. Such is the general description of a locality which has acquired considerable celebrity in connection with the question of the antiquity of man. The Quaternary deposits of Moulin-Quignon and the peat-beds of the Somme formerly furnished Cuvier with some of the fossils he described, and in later times chipped flint-implements from the quarries and bogs came into the possession of M. Boucher de Perthes; the statements were received at first not without suspicion — especially on the part of English geologists who were familiar with similar attempts on their own credulity — that some at least of these were manufactured by the workmen of the district. At length, the discovery of a human jaw and tooth in the gravel-pits of St. Acheul, near Amiens, produced a rigorous investigation into the facts, and it seems to have been established to the satisfaction of Mr. Prestwich and his colleagues, that flint-implements and the bones of extinct Mammalia are met with in the same beds, and in situations indicating very great antiquity. In the sloping and irregular deposits over^ looking the Somme, the bones of Elephants, Rhinoceros, with land and fresh-water shells of existing species, are found mingled with flint-implements. Shells like those now found in the neighbouring streams and hedge-rows, with the bones of existing quadrupeds, have been obtained from the peat, with flint-tools of more than usual finish, and together with them a few fragments of human bones. Of these reliquiae, the Celtic memorials lie below the Gallo-Roman; above them, oaks, alders, and walnut trees occur, sometimes rooted, but no succession of a new growth of trees appear.

The theory of the St. Acheul beds is this: they were deposited by fluviatile action, and are probably amongst the oldest deposits in which human remains occur, older than the peat-beds of the Somme — but what is their real age? Before submitting to the reader the very imperfect answer this question admits of, a glance at the previous discoveries, which tended to give confirmation to the observations just narrated, may be useful.

Implements of stone and flint have been continually turning up during the last century and a half in' all parts of the world. In the

•neighbourhood of Gray's Inn Lane, in 17 15, a flint spear-head was picked up, and near it some Elephants' bones. In the alluvium of the Wey, near Guildford, a wedge-shaped flint-tool was found in the gravel and sand, in which Elephants' tusks were also found. Under the clifls at Whitstable an oval-shaped flint-tool was found in what had probably been a fresh-water deposit, and in which bones of the Bear and Elephant were also discovered. Between Heme Bay and Reculver five other flint-tools have been found, and three more near the top of the cliff, all in fresh- water gravel. In the valley of the Ouse, at Beddenham, in Bedfordshire, flint-implements, like those of St. Acheul, mixed with the bones of Elephant, Rhinoceros, and Hippopotamus, have been found, and near them an oval and a spear-shaped implement. In the peat of Ireland great numbers of such implements have been met with. But nowhere have they been so systematically sought^ for and classified as in the Scandinavian countries.

The peat-deposits of those countries — of Denmark especially — are formed in hollows and depressions, in the northern drift and Boulder clay, from ten to thirty feet deep. The lower stratum, of two or three feet in thickness, consists of sphagnum^ over which lies another growth of peat formed of aquatic and marsh plants. On the edge of the bogs trunks of Scotch firs of large size are found — a tree which has not grown in the Danish islands within historic times, and does not now thrive when planted, although it was evidently indigenous within the human period, since Steenstrup took with his own hands a flint-implement from beneath the trunk of one. The sessile variety of the oak would appear to have succeeded the fir, and is found at a higher level in the peat. Higher up still, the common oak, Querais robur, is found along with the birch, hazel, and alder. The oak has in its turn been succeeded by the beech.

Another source from which numerous relics of early humanity have been taken is the midden-heaps (Kjokken-modden) found along the Scandinavian coast. These heaps consist of castaway shells mixed vn\h bones of quadnipeds, birds, and fishes, which reveal in some respects the habits of the early races which inhabited the coast. Scattered through these mounds are flint-knives, pieces of pottery, and ashes, but neither bronze nor iron. The knives and hatchets are said to be a degree less rude than those of older date found in the peat. Mounds corresponding to these, Sir Charles Lyell tells us, occur along the American coast, from Massachusetts and Georgia. The bones of the quadrupeds found in these mounds correspond with those of existing species, or species which have existed in historic times.

By collecting, arranging, and comparing the flint and stone implements, the Scandinavian naturalists have succeeded in establishing a chronological succession of periods, which they designate — i. The Age of Stone; 2. The Age of Bronze; 3. The Age of Iron. The flrst, or Stone period, in Denmark, corresponded with the age of the Scotch fir, and, in part, of the sessile oak. A considerable portion of the oak period corresponded, however, with the age of bronze, swords made of that metal having been found in the peat on the same level with the oak. The iron age coincides with the beech. Analogous instances, confimiatory of these statements, occur in Yorkshire, and in the fens of Lincolnshire.

The traces left indicate that the aborigines went to sea in canoes scooped out of a single tree, bringing back deep-sea fishes. Skulls obtained from, the peat and from tumuli, and believed to be contemporaneous with the mounds, are small and round, with prominent supra-orbital ridges, somewhat resembling the skulls of Laplanders.

The third series of facts {Lake-dwellings, or lacustrine habitations^ consisted of the buildings on piles, in lakes, and once common in Asia and Europe. They are first mentioned by Herodotus as being used among the Thracians of Pasonia, in the mountain-lake Prasias, where the natives lived in dweUings built on piles, and connected with the shore by a narrow causeway, by which means they escaped the assaults of Xerxes. Buildings of the same description occupied the Swiss lakes, in the mud of which hundreds of implements, like those found in Denmark, have been dredged up. In Zurich, Moossee-dorf near Berne, and Lake Constance, axes, celts, pottery, and canoes made out of single trees, have been found; but of the human frame scarcely a trace has been discovered. One skull dredged up at Meilen, in the Lake of Zurich, was intermediate between the Lapp-like skull of the Danish tumuli and the more recent European type.

The age of the different formations in which these records of the human race are found will probably ever remain a mystery. The evidence which would make the implements formed by man contemporaneous with the Mammoth and other great Mammalia would go a great way to prove that man was also pre-glacial. Let us see how that argument stands. At the period when the upper Norwich Crag was deposited, the general level of the British Isles is supposed to have been about 600 feet above its present level, and so connected with the European continent as to have received the elements of its fauna and flora from thence. By some great change, a period of depression occurred, in which

all the country north of the mouth of the Thames and the Bristol Channel was placed much below the present level. Moel Tryfaen experienced a submergence of at least 1,400 feet, during which it received the erratic blocks and other marks, indicative of floating icebergs, which have been described in a former chapter. The country was raised again to something like its original level, and again occupied by plants, Molluscs, Fishes and Reptiles, Birds, and IMammifera. Again subsidence takes place, and, after several oscillations, the level remains as we now find it. The estimated time required for these various changes is something enormous, and might have extended the term to double the number of years. The unit of the calculation is the upward rate of movement observed on the Scandinavian coast; applied to the oscillation of the ancient coast of Snowdonia, the figures represent 224,000 years for the several oscillations of the glacial period. Adding the pre-glacial period, the computation gives an additional 48,000 years. But, let us repeat, the figures and data are somewhat hypothetical.

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