Relics of the kinds above cited have been found at intervals for many years past, but their age and significance were doubted, and only within some forty years has the great antiquity of man upon the earth been generally acknowledged by scientists. The most important early find of ancient implements was made by Boucher de Perthes in 1841 and subsequently, in the high level gravels of the valley of the Somme, in Picardy, France. In deep layers of these gravels, which were deposited at a period when the river occupied a wider and higher channel than at present, he found rude flint weapons and tools, bearing plain evidences of human workmanship, and mingled with the teeth and bones of animals, both of living and extinct species. Among the bones were those of the mammoth and the hairy rhinoceros, species evidently contemporary with man, though they have long since vanished from the earth. At a somewhat earlier date, implements of men, mingled with bones of the cave-bear, cave-lion, hyena, and other species, had been found in the caves of France and Belgium. These were frequently buried beneath deposits of stalagmite and other materials that must have taken a long time to accumulate. The significance of these discoveries was long in forcing itself upon the attention of scientific men. Nearly twenty years passed before Boucher de Perthes could get the noted geologists of France and England to investigate the Somme gravels. When they did so they were quickly convinced of the genuine antiquity of these relics, and announced it as a fact beyond question that man had lived in the Somme valley and fashioned rude implements out of flint during what was known as the Quaternary or Drift Period of geology. The discoveries here made set men actively at work investigating elsewhere. Excavations were made in other high level gravels, caverns were carefully and minutely examined, Kent's Cavern, England, was dug out to its rock bottom, dozens of important finds resulted, and the antiquity of man was proved to extend back from thousands to tens of thousands, if not to hundreds of thousands, of years. And the coexistence of man with the animals whose bones accompanied his relics was proved by unquestionable evidence, for drawings and carved forms of these animals were found, proving incontestably that man had gazed upon their living forms. Thus the sketch of a mammoth, showing the long hair which served to protect this animal from the cold, was found engraved upon a piece of mammoth ivory, and one of a group of reindeer on a piece of reindeer horn. There were also drawings of the cave-bear, the seal, etc., and one very interesting group showing the aurochs, a number of trees, and a man with a snake apparently biting his heel. The carvings consisted of the horn handle of a dagger, cut into the shape of a reindeer, and other forms.