Over 1,000 mine pits on one island, some 20 feet deep - dug with no iron and no powder

In eighteen seventy-four a crew at the Minong Mine on Isle Royale cut down through sixteen and a half feet of rock and hit a single mass of native copper weighing five thousand seven hundred and twenty pounds. Underneath it were wooden poles, which means somebody had already worked that mass free of the bedrock, gotten timber in under it for a lift, and then walked away from the job thousands of years before the steam hoists arrived. This is the story of the Isle Royale copper pits: more than a thousand of them along Minong Ridge, some twenty feet deep in hard rock, dug without iron and without powder, dated by the Park Service to around two thousand five hundred BCE and by a two thousand fifteen sediment core from McCargoe Cove to as early as six and a half thousand years ago. The pits gave back stone hammers in great numbers, a wooden bowl about three feet across, a small wooden shovel with a blade under five inches wide, and timber cut by an axe whose bit measured about two inches. The great mass itself stood in a courthouse yard in Detroit, went to the Centennial Exposition in Philadelphia in eighteen seventy-six, and was then fused and sold as commercial copper, taking every ancient hammer mark on its surface into a furnace. What remains unexplained is simpler and stranger than any of it: on an island fifteen miles out in Lake Superior, worked for at least fifteen centuries, no habitation site from the mining period has ever been found. If you like history told from the documents themselves, with the gaps left open where they belong, stay with the channel for the next file.