Lead and zinc mining in the Driftless Area

ABSTRACT Lead and zinc ore minerals occur in the middle Ordovician Sinnipee Group dolomites in southwest Wisconsin and adjacent areas of northwest Illinois and northeast Iowa. Europeans began mining lead deposits as early as the mid-1600s; production of lead ore and smelting of lead reached a peak ca. 1850. Mining and production from the stratigraphically lower zinc deposits reached a peak in 1917, with a lesser resurgence of zinc production ca. 1950–1970. The mining detritus and sediment from mine waste piles is relatively stable. However, cations of lead and zinc freely adsorb to clay and silt particles and have been incorporated into the downstream fluvial systems. The temporal coincidence of lead-zinc mining and active aggradation of many fluvial systems in the Driftless Area has resulted in these “legacy sediments” being preserved in overbank fluvial deposits throughout the Lead-Zinc District.