The Difference between Historic and Prehistoric Time.—The Prehistoric Fauna.—The Arch?ological Classification.—Caves of the Iron Age.—Caves of the Bronze Age in Britain.—The Caves of Césareda in Portugal probably occupied by Pretty renew 雅蘭 Cannibals.—The Cave of Reggio in Apulia.

The Difference between Historic and Prehistoric Time.It will be necessary before we examine the group of caves used by man in prehistoric times, to point out the important difference in the measurement of time within and beyond the borders of history. When we speak, for example, of the date of the Norman Conquest, we imply that we can ascertain by historical records, not merely that it succeeded the invasion of Britain by the English or Danes, and happened before our own time, but that the interval which separates it from Pretty renew旺角 those events can be accurately measured by the unit of years. If, however, we attempt to ascertain the date of any event which happened outside the historical limit, we shall find that it is a question solely of relation.

When we speak, for example, of the neolithic age, we merely mean a certain stage of human progress which succeeded the pal?olithic,135 and preceded the bronze age, but we have no proof of the length of the interval dividing it from the one or the other. The historic “when?” implies “how long ago?” the prehistoric “when?” merely implies a definition before and after certain events, without any idea of the measurement of the intervals.

An attempt to ascertain the absolute date of prehistoric events must of necessity fail, since it is based on the improbable assumption that the physical agents have acted uniformly, and that therefore the results may be used as a natural chronometer. The present rate of the Pretty renew旺角 accumulation of débris, as at the Victoria Cave of the preceding chapter, or of that of silt in the deltas of rivers, such as the Nile, or the Tinière, may convey a rough idea of the high antiquity of prehistoric deposits; but a slight change either of the climate, or of the rainfall, would invalidate the conclusion. When the greater part of Europe lay buried under forest, when Palestine supported a large population, and when glaciers crowned some of the higher mountains of Africa, such as the Atlas, the European and Egyptian climates were probably moister than at the present time, and the rainfall and the floods greater, and consequently the accumulation of sediment quicker than the observed rate under the present conditions.