[Illustration: Eskimo by their winter huts; drawn by an Eskimo]
So you see that by the Age of Stone is meant a time when the metals—tin and copper and iron—were not known; and when stone, horn, bone, shell, and wood were used for tools and weapons. The cave men were in the Stone Age long ago. The Eskimo are in the Stone Age now. And the American red men, though they were still in the Stone Age, were beginning to learn the use of one metal—copper.
And the people of the shell mounds—how do we know about them? In Denmark to-day you may see shell mounds. They are the old hunting and fishing villages. They are of different sizes; some are a quarter of a mile long and half as wide. They are built up of things that the hunters and fishermen threw away: oyster and mussel and periwinkle shells; bones of the wolf, the hyena, the dog; of wild duck, swan, and grouse; of cod, herring, flounder, and other deep-sea fish. Many of the bones had been split open for the purpose of extracting the marrow. Besides bones, there are also pieces of burnt wood; and there is sea plant, which may have given salt.
