The Mound-Builders were greatly more in advance of the Indian hunter than behind the civilised Mexican. They had acquired habits of combined industry; were the settled occupants of specific territories; and are proved, by numerous ornaments and implements of copper deposited in their monuments and sepulchres, to have been familiar with the mineral resources of the northern lake regions, whether by personal enterprise, or by a system of exchange. What probabilities there are suggestive of a connection between the Mound-Builders and the ancient Miners will be discussed in a later chapter, along with other and allied questions; but to just such a race, with their imperfect mechanical skill, their partially developed arts, and their aptitude for continuous combined operations, may be ascribed, _à priori_, such mining works as are still traceable on the shores of Lake Superior, overshadowed with the forest growth of centuries. The mounds constructed by the ancient race are in like manner overgrown with the evidences of their long desertion; and the condition in which recent travellers have found the ruined cities of Central America, may serve to show what even New York, Washington, and Philadelphia: what Toronto, Montreal, and Quebec, would become after a very few centuries, if abandoned, like the desolate cities of Chichenitza or Uxmal, to the inextinguishable luxuriance of the American forest growth. The accumulations of vegetable mould, the buried forests of older generations, and the living trees with their roots entwined among the forsaken implements of the miners, all point to the lapse of many centuries since their works were abandoned. Changes wrought on the river-courses and terraces in the Ohio valleys suggest an interval of even longer duration since the construction of the great earthworks with which that region abounds. But to whatever period the working of the ancient copper mines of Lake Superior be assigned, the aspect presented by some of them when reopened in recent years is suggestive of peculiar circumstances attending their desertion. It is inconceivable that the huge mass of copper discovered in the Minnesota mine, resting on its oaken cradle, beneath the accumulations of centuries, was abandoned merely because the workmen, who had overcome the greatest difficulties in its removal, were baffled in the subsequent stages of their operations, and contented themselves by chipping off any accessible projecting point. Well-hammered copper chisels, such as lay alongside of it, and have been repeatedly found in the works, were sufficient, with the help of stone hammers, to enable them to cut it into portable pieces. If, indeed, the ancient miners were incapable of doing more with their mass of copper, in the mine, than breaking off a few projections, to what further use could they have turned it when transported to the surface? It weighed upwards of six tons, and measured ten feet long and three feet wide.