Sulfate-mineral crusts from pyrite weathering and acid rock drainage in the Dakota Formation and Graneros Shale, Jefferson County, Nebraska

The acid-sulfate weathering sites described herein seem to be relatively unique in the surrounding region. Nonetheless, the study of these sites suggests that there are potentially widespread effects of natural acid-sulfate weathering associated with the Dakota Formation and other pyritiferous Cretaceous strata in the region, and that the localized effects of anthropogenically induced acid-sulfate weathering in roadcuts, quarries, and other excavations can present engineering problems. Acid-sulfate weathering is likely to have influenced the development of regional groundwater chemistry during the Quaternary and may create adverse engineering and environmental conditions, such as the retardation of vegetation cover, encouragement of subsoil gypsum growth, acceleration of shale slaking, and possibly even the corrosion of roadbed materials.