As to why the mammoth became extinct, we _know_ absolutely nothing, although various theories, some much more ingenious than plausible, have been advanced to account for their extermination--they perished of starvation; they were overtaken by floods on their supposed migrations and drowned in detachments; they fell through the ice, equally in detachments, and were swept out to sea. But all we can safely say is that long ages ago the last one perished off the face of the earth. Strange it is, too, that these mighty beasts, whose bulk was ample to protect them against four-footed foes, and whose woolly coat was proof against the cold, should have utterly vanished. They ranged from England eastward to New York, almost around the world; from the Alps to the Arctic Ocean; and in such numbers that to-day their tusks are articles of commerce, and fossil ivory has its price current as well as wheat. Mr. Boyd Dawkins thinks that the mammoth was actually exterminated by early man, but, even granting that this might be true for southern and western Europe, it could not be true of the herds that inhabited the wastes of Siberia, or of the thousands that flourished in Alaska and the western United States. So far as man is concerned, the mammoth might still be living in these localities, where, before the discovery of gold drew thousands of miners to Alaska, there were vast stretches of wilderness wholly untrodden by the foot of man. Neither could this theory account for the disappearance of the mastodon from North America, where that animal covered so vast a stretch of territory that man, unaided by nature, could have made little impression on its numbers. That many were swept out to sea by the flooded rivers of Siberia is certain, for some of the low islands off the coast are said to be formed of sand, ice, and bones of the mammoth, and thence, for hundreds of years, have come the tusks which are sold in the market beside those of the African and Indian elephants.