Onsite measurements of pH, specific conductance, and water temperature show that water in seven mine shafts in northeastern Oklahoma and southeastern Kansas is stratified. With increasing sampling depth, specific conductance and water temperature tend to increase, and pH tends to decrease. Concentrations of dissolved solids and chemical constituents in mine-shaft water, such as total and dissolved metals and dissolved sulfate also increase with depth. The apparently unstable condition created by cooler, denser water overlying warmer, less dense water is offset by the greater density of the lower water strata due to higher dissolved solids content.