By Halsey, John R.
Michigan History Magazine , Vol. 93, No. 3
In the late 1840s, copper miners in the western Lake Superior basin became aware that someone had been mining there before them. In reality, for several thousand years prior to European contact in the 1600s, prehistoric people had been mining copper to make thousands of tools, weapons and items of adornment. With this realization came curiosity about who had done the mining, how long ago and how much copper had been removed. Eventually, evidence of prehistoric copper mining in the form of thousands of pits called "Indian" or "ancient diggings" would be found over a swath 150 miles long and four to seven miles wide across Keweenaw,
Houghton and Ontonagon counties. As the miners cleared out these pits before establishing their own operations, a significant number of them recorded their observations and ideas.
Where did you find information on these prehistoric mines? Wasn't the western Upper Peninsula mostly a wilderness in the mid-nineteenth century?
The presence of native copper in the western Upper Peninsula had been known since the mid-1600s. The Ontonagon Boulder, a large mass of native copper on the bank of the Ontonagon River (now in the Smithsonian Institution) had been a pilgrimage point for European and American explorers for generations. Douglass Houghton's explorations in the 1830s and 1840 had provided the impetus for explorers and prospectors to look to the U. P. to make their fortunes. Along with them came storekeepers, tavern owners and newspapermen. I have made a systematic effort at locating all extant early references relating to prehistoric mining focusing on pioneering newspapers, mining company annual reports and company prospectuses from the Copper Country.
Who were the people that reported these findings?
The most dependable information comes from the mine agents, captains and superintendents, the highest ranking company men on the scene, and those most likely to be made aware of unusual or important discoveries made by the men in the mines. By contemporary standards, they were educated and had a broad base of real-world experience. The principal problem facing these pioneers was that no miners anywhere had ever dealt with native copper deposits of the size, richness and irregularity of those in the western Lake Superior basin.
Over their career, most of these men worked for several mining companies, sometimes offering assessments of the economic potential of new mining properties while employed by another. Newspapermen George D. Emerson and William J. Tenney offered immediate comments on discoveries being made in their localities. Although most have been forgotten, the contributions of some, notably Charles Whittlesey, live on today.
It is clear that quite a number of high-ranking officials across the spectrum of mines thought the evidence from the ancient diggings and their contents was of exceptional importance for economic reasons. Perhaps the most dramatic example of this was the 1875 prospectus of the Minong Mining Company on Isle Royale in which eleven pages are devoted to the history and firsthand descriptions of "ancient diggings." I have identified seventy-seven individuals credited with discovery or reporting at sixty-seven locations that became working copper mines.
How did the prehistoric miners become aware of the native copper deposits?
Their first experience with native copper was probably the discovery of "drift" or "float" copper; pieces of copper ripped by glaciers from the veins and lodes of copper escaped in the bedrock and distributed over much of the Midwest more than ten thousand years ago. In prehistoric times, many copper veins were exposed at the ground surface. After their discovery of bedrock copper, the prehistoric miners appear to have focused their attention on that source. However, there is strong evidence that they dug for loose copper in the nearby glacial sands and gravels. …