If we take as the first of the problems to be examined on this subject, that which seems the most likely to be answered on satisfactory evidence, viz. the geological antiquity of the human race, we find clear though incomplete testimony leading to a sure and definite conclusion. Man and the works of man have been preserved in natural repositories of higher antiquity than all the mausoleums, and tumuli, and Úπоyаîa; in caverns, peat-bogs, lacustrine and riversediments, which derived their characteristic features from the operation of physical conditions long since passed away. Thus deep in the sediments of many of our British valleys left by the rivers in some earlier period, we find the canoe of the primitive inhabitant, hollowed by fire and rude stone chisels from the trunk of the native oak. In Caverns near Swansea, and near Narbonne, skeletons of the early people have been found; in those of Kent's hole and Brixham and Sicily, and deep in the gravel of Amiens and Abbeville, the flint instruments which served for rude workmen in wood, rude diggers of the ground, or rude warriors in the field. According to such observations as we can make these facts can only be explained by supposing a long period of time to have elapsed since their occurrence. To heap twenty or more feet of sediment over the buried canoes by the ordinary operation of a river like the Yorkshire

Aire, would require thousands of years; if it were not accumulated under the ordinary circumstances now in operation, but under different geographical conditions, this would perhaps require the hypothesis of still longer time. In the alluvial sediments of this same valley lie nearly complete skeletons of the extinct Hippopotamus major1; in another place jaws and horns of the deer, and hazel wood and nuts, some of them petrified'. Perhaps man was contemporary with this extinct Hippopotamus, which has also been found in the Peat deposits of Lancashire.

The gravel of Amiens and Abbeville appears to furnish evidence of higher antiquity for the flint implements found there, for they lie at the bottom of the deposit, 20 ft. or more in depth. The deposit is of fluviatile origin, but it is not in the bed of the actual valley. It lies in what must have been the course of the great floods of some earlier time, under other geographical conditions, before the actual riverchannel was sunk to its present level. In this gravel have been found remains of Elephas primigenius, now extinct. Man may have been contemporary with that animal in Europe; nor will this appear a very startling inference, if we remember the discovery of the entire specimen covered with flesh and hair at the mouth of the Lena.

1 British Association Reports, 1853.

R. L.

2 Phil. Mag. 1827.

E

But how many soever of centuries we allow for the accumulation of the gravel, the filling of the caves, or the deposition of the alluvium, this period thus indicated is as nothing compared to those which have passed away before it began. In a general summary we may affirm that the human period of the earth's history is a very short one on the geological scale, the latest of all, and yet the most important, since independent of the interest conferred on it by the presence of our race, it is by evidence collected from this period that we are to judge of the earlier ages of nature.

If we put as our second question the geological antiquity of the races of plants and animals which are directly and specially associated with man, as the valuable Pomaceous Plants and Ruminant Animals, the answer is of the same kind. They are of recent date their remains are found only in deposits near the surface, which belong to the existing order of physical conditions, the later effects of geological agencies. The creatures most useful to him appear to be of contemporaneous origin; and may be employed as marks of the human period, in cases where no traces of man or his works remain. The relation of this to earlier periods will appear in the following scale of geological time, the length of the periods being not perhaps exactly proportioned to the thick

nesses of the systems of strata, but yet (as will be shewn hereafter) undoubtedly to some extent represented by them.

In this scale the total thickness of the Fossiliferous strata, down to the Lingula beds of Wales, is assumed to be 10 miles, 52800 ft. That is not the maximum thickness, which in Britain is supposed by Ramsay to be 72584 ft. In his estimate the Palæozoic beds are taken much above the average, and the Cenozoic beds much below the average of Europe, Morris gives the maximum numbers thus, Cenozoic 2830, Mesozoic 6170, Palæozoic 49460. D'Orbigny's general statement gives 21260 metres =69750 ft., the Tertiary occupying 9842 ft., while in England they are supposed to be 2240. The figures on the left may be used to mark miles of depth, thickness of deposits, or periods of unknown duration, according to the purpose in view.

The Geological Scale of Time thus constituted by the succession of marine strata, is liable to the objection which applies to almost every scale of historical time, that it is not complete in any one region, no one oceanic basin having been yet discovered which has received marine sediments continuously through all geological periods. The remedy is the same as in ordinary history-the scales of different regions are combined by means of common terms, which in one