Proved by Contemporary Monuments--As in History--Summary of Historical Evidence--Geological Evidence of Human Periods--Neolithic Period--Palæolithic or Quaternary--Tertiary--Secondary and Older Periods--The Recent or Post-Glacial Period--Lake-Villages--Bronze Age--Kitchen-Middens--Scandinavian Peat-mosses--Neolithic Remains comparatively Modern--Definition of Post-Glacial Period--Its Duration--Mellard Read's Estimate--Submerged Forests--Changes in Physical Geography--Huxley--Objections from America--Niagara--Quaternary Period--Immense Antiquity--Presence of Man throughout--First Glacial Period--Scandinavian and Laurentian Ice-caps--Immense Extent--Mass of _Débris_--Elevation and Depression--In Britain--Inter-Glacial and Second Glacial Periods--Antiquity measured by Changes of Land--Lyell's Estimate--Glacial _Débris_ and Loess--Recent Erosion--Bournemouth--Evans--Prestwich--Wealden Ridge and Southern Drift--Contain Human Implements--Evidence from New World--California. We have now to take leave of historical records and fall back on the exact sciences for further traces of human origins. Our guides are still contemporary records, but these are no longer stately tombs and temples, massive pyramids and written inscriptions. Instead of these we have flint implements, incised bones, and a few rare specimens of human skulls and skeletons, the meaning of which has to be deciphered by skilled experts in their respective departments of science. Still these records tell their tale as conclusively as any hieroglyphic or cuneiform writings in Egyptian manuscripts or on Babylonian cylinders. The celt, the knife, the lance and arrow-heads, and other weapons and implements, can be traced in an uninterrupted progressive series from the oldest and rudest palæolithic specimens, up to the highly-finished ones of polished stone, and through these into the age of metals, and into historic times and the actual implements of existing savage races. It is impossible to doubt that one of the palæolithic celts from St. Acheul or St. Prest is as truly a work of the human hand, guided by human intelligence, as a modern axe; and that an arrow-head from Moustier or Kent's Cavern is no more an elf-bolt, or a _lusus naturæ_, than is a Winchester rifle.