In till, concentrations of both smelter and non-smelter related elements show no direct relationship to distance from the smelter, but appear to be related to the natural variation in bedrock composition and the effects of glacial transport. Metal concentrations in till are generally higher over Precambrian rocks, particularly in till derived from metavolcanic rocks naturally enriched in heavy metals. Over the Paleozoic cover, the till is calcareous and commonly depleted in most trace elements. Vertical geochemical profiles from detailed studies indicate little downward migration of metals from the organic rich layers.