[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.
[Illustration: A bone awl; found in a cave in England]
The stone tools and weapons found in the heaps are axes, knives, hammers, awls, lance heads, and sling stones—all of rude make. There are also bits of rude pottery, which show that these men knew a little more than the cave men; they knew how to bake clay. They were ahead of the cave men also in having one tamed animal—the dog. No bones were found of any tamed animal except the dog, and this seems to show that it was the earliest animal tamed by man.
Mounds like those in Denmark are found in many other countries: in our own land where the red men lived; in Africa, the land of the black man; and in Asia, where the brown man lives. Wherever man has led a wandering life, eating fish and leaving their bones behind him, these heaps are found; and they are always by the sea or by a river.