The surface mines are usually nearly filled with leaves and vegetable mould that have accumulated during the centuries that have elapsed since their abandonment, and till within a few years a heavy growth of timber covered the land; hence the numerous slight depressions that occurred along the line of the vein excited no suspicion that they were artificial excavations. By the closest observers they were regarded as natural depressions, caused either by the disintegration of the underlying rock or the peculiar manner in which the overlying drift was deposited. In many of these depressions, which have proved to be abandoned mines, trees of enormous size are found growing, some of which are ascertained, by counting their concentric rings, to be four hundred years old. At the Hilton Mine, directly over the leather bag before alluded to, there was a hemlock-tree about three feet in diameter. I noticed the stump of a tree nearly four feet in diameter in a gap near the Rockland Mine, where a hill had been actually cut asunder by these ancient miners, and a deep valley formed by the removal of the rock. Until very recently this valley was not recognized as an ancient mine; for, being ten rods in width, and cutting nearly at right angles across the strata of the rock that formed the hill, it was considered too extensive to have been made by human hands, and was supposed to be the result of natural causes. But about two years since, during a very dry time, a destructive fire swept through the woods, and so completely burned up all the vegetable matter accumulated there as to expose the underlying rock, and reveal its true character. After the fire had done its work, it was found that copper veins, which had been worked, ran through the rock in the gap, and that the great bank upon the south side of the hill, which was supposed to be a terraced gravel bank, proved to be a vast accumulation of "attle," or refuse stone, that had been taken from the artificial gap and deposited there. The stones forming this immense pile are generally small, and appear to have been broken up by heating to facilitate their removal from the mine, and possibly may have been again broken, with the hope of finding copper in them. In the midst of the pile I noticed several stone hammers, or mauls, some of them measuring twenty inches in girth around their grooves, and one I brought away weighing thirty pounds.