Collections of nearly 20,000 copper implements of twenty-one general types, heavily patinated, all surface or near surface finds without apparent pottery association, found in maximum concentration in Wisconsin, have raised questions of their relative age and probable cultural affiliations. In 1942, after Ritchie's discovery of copper implements in pre-pottery Laurentian levels, W. C. McKern (1942, p. 167) formulated a provisional hypothesis. He defined the tools as the production of a pre-Woodland, preceramic people, centered in Wisconsin and spreading into adjacent territory, and subsumed all copper implements, not attributable to known cultures, as cases of the Old Copper Industry.