After concluding my expeditions to the lands and ponds of the beavers, I went to that part of Michigan where the ancient mining pits and trenches have been discovered. The earliest knowledge of them was obtained by an American explorer who, in the year 1847, when seeking for indications of metal ore, noticed several depressions in the ground, and saw lying in a heap, near what seemed to be an ancient excavation, a number of rude stone hammers that he thought had probably been used by hand.
In the following year another excavation was discovered, and after clearing this out to a depth of eighteen feet, there was found a detached mass of copper weighing over six tons which rested upon oak sleepers, and beneath it there was a vein of copper five feet thick. There were also several stone hammers, grooved for the purpose of having handles attached to them, and a copper chisel with a socket for a wooden handle, a fragment of which although much decayed, was still in its place. In an adjoining pit at a depth of ten feet, there was a wooden bowl and some charcoal.[11] In some workings, subsequently discovered upon Isle Royale and near the end of the Kee-wai-wona promontory, a number of wooden wedges were seen, together with traces of extensive trenches.
In consequence of these discoveries further investigations were made, and a large number of ancient pits were found in the forests, especially in the districts where are now placed the towns of Ontonagon and Houghton. It was within a few miles from the latter town, that the explorers observed the heap of stone hammers, and their attention was directed to the fact that they had been preceded in the search for copper by men of some unknown race, who possessed capacities for mining operations greater than could be attributed to the Chippewas who then occupied the land.
In order to examine this heap I engaged a man—who knew the mining and forest region—to guide me to the spot where the hammers still remained. After crossing the Portage Lake and passing over some low neighbouring hills, we came to a depression in the ground which looked like an old ditch or trench. At the side of this ditch, I saw several hundreds of rounded water-worn stones of various sizes. These had evidently been chosen on account of the convenience of their shape, for the purpose of being used for crushing the rocks that contained metal.
A few of the stones appeared to have been partly shaped by hand, but the majority of them were in their natural form. Several were perforated by small round holes, caused probably by the action of water. Some men who happened to be employed at one of the mines in the neighbourhood, told me that in their opinion they had been made for thumb holes. They were, however, much too small for such a purpose.
Upon my return to Houghton I met Mr. I. H. Forster, who was the agent for mines and a Senator for the State. He proposed to accompany me to the sites of those ancient workings that he had personally inspected. After passing through a forest of birch and pine trees, we reached an open space where we saw the evidences of the nature of the operations that had been executed.
The direction of the trenches could be easily traced, although they were filled with earth and leaves. Several of the pits had been cleared out by the men employed at one of the new mines, and it was therefore possible to go down to the bottom of them and observe the methods of excavation. The first that I examined was twelve feet deep; from the base there ran two nearly horizontal galleries or adits, following the direction of the lode which ran N.W. and S.E. These adits were five feet wide and extended laterally about six feet. Upon the surface, near the edge of the pit, was the stump of a basswood tree, six feet in circumference, and at the opposite edge was the stump of a pine, four feet in circumference.
The second pit was twenty yards from the first, and had evidently been sunk in the direction required in order to reach the same lode. It was ten feet deep. From the base there was one adit following the direction of the deposit of copper. Close to the edge of this pit was the stump of a small birch tree. Beyond this were seven other pits, from twenty to fifty yards apart, and in connection with these, there were several short trenches from two to four feet wide.
The pits were discovered in 1865. Some animals were being driven along a track in the forest, when one of them straying from the path, plunged his feet deep into the ground; this was noticed, and an explorer for copper examined the place and pushed his stick down it. This led to a further search, and the hole was found to be an ancient pit. Shafts were sunk, and the result has been, that, one of the most important mines in the district was established near the spot.
Upon another occasion I went with Mr. Forster to look at the trenches and pits that had been found in a more distant part of the forest. These pits were smaller than those that I had previously seen, but the trenches were frequently of considerable depth. I measured several that exceeded six feet deep. These trenches were usually in short lengths, but one of them was nearly two hundred feet long. Upon making inquiries amongst the leading men of the various copper mines that have been placed in the neighbourhood of the earlier workings, I was told that the practical miners were of opinion that these excavations were of considerable antiquity. It has, however, been proved by the condition of the things that were found in the pits that these conjectures are not well founded.