The Animals—Magnitude of Interval.
The prehistoric mammalia consist, as we have seen (p. 136), with the solitary exception of the Irish elk, of the wild animals at present living in Europe, together with the domestic species and varieties introduced by man, probably from central Asia. In the rest of this work we shall have to deal, not merely with the wild animals at present inhabiting Europe, but also with those which have either become extinct, or have migrated to Asia, America, or Africa. Besides this addition to the European fauna in the pleistocene age, the total absence of the domestic animals is a most important feature. The dog, goat, sheep, Celtic short-horn, and domestic swine are conspicuous by their absence: the reputed association of their remains with those of the pleistocene mammals being due, in all the cases which I have examined in France and Britain, to a confusion between distinct strata in the same cave or river-deposit, which are respectively of pleistocene and prehistoric or historic ages. Thus in the excavations in the gravel underneath London, the Celtic short-horn and goat of the superficial strata are very generally mixed with the reindeer and mammoth of the pleistocene gravels below, by the collectors, and the names of the domestic animals have crept into the pleistocene lists. None of the domestic animals have been recorded from any carefully explored strata of that age in any part of Europe.
The following late pleistocene species were unknown in Britain in the prehistoric age:—
Glutton.
Spotted hyæna.
Panther.
Lion.
Lynx.
Felis Caffer.
Musk-sheep.
Bison.
Hippopotamus.
Lemming.
Pouched marmot.
Tailless hare.
Lepus diluvianus.
Arvicola Gulielmi.
Cave-bear.
Rhinoceros hemitœchus.
R. tichorhinus.
Elephas antiquus.
Mammoth.
The glutton, lynx, bison, and lemming, still live in Europe, the spotted hyæna, Felis Caffer, and hippopotamus are peculiar to Africa, the lion to Africa and Asia, and the last seven species are extinct. The Machairodus cultridens and Rhinoceros megarhinus probably disappeared in an early stage of the pleistocene. It may reasonably be inferred, from the migration and extinction of so many species between the close of the pleistocene and beginning of the historic period, that the interval was of considerable length; for it would be impossible for such changes to have taken place in a short time.
The same sharp line of demarcation exists between the two faunas on the continent. The panther, Felis Caffer, lynx, spotted hyæna, musk-sheep, hippopotamus, and the extinct group disappeared. The African elephant forsook Spain and Sicily, the striped hyæna the south of France, before the prehistoric period; while the Elephas meridionalis and pigmy hippopotamus of Sicily, and the pigmy elephant and gigantic dormouse of Malta, became extinct. Speaking in general terms, the wild fauna of Europe, as we have it now, dates from the beginning of the prehistoric age, and consists merely of those animals which were able to survive the changes by which their pleistocene congeners were banished or destroyed. The arrival of the domestic animals under the care of man in the neolithic age, and their extension over the whole of Europe in a wild or semi-wild state, coupled with the disappearance of the wild species mentioned above, constitutes a change in the mammal life at least as important as any of those which define the meiocene from the pleiocene, or the pleiocene from the pleistocene periods.
Physical changes—The excavation and filling up of Valleys.
The magnitude of the interval between the two periods may also be gathered from the great changes which have taken place in physical geography. In nearly every valley in Great Britain, certain areas to be mentioned presently excepted, are strata of sand and gravel, proved to be of pleistocene age by their fossil mammals, and by their fluviatile shells to have been deposited by rivers. They occur at various heights, forming sometimes terraces, and at others isolated patches, which were accumulated when the river flowed at their level, and before the valleys were cut down to their present depth. Those at Fisherton near Salisbury, described by Sir Charles Lyell, Mr. Prestwich, Mr. John Evans,[175] and others, may be taken as an example.
