Postdepositional alteration of surface and near-surface minerals in selected coastal plain formations of the Middle Atlantic States

Abstract

The depth and intensity of postdepositional subaerial weathering were examined in several Coastal Plain formations from New Jersey to Virginia. This region was divided into three study areas: (1) west of Chesapeake Bay, (2) between Chesapeake and Delaware Bays (Delmarva Peninsula), and (3) northeast of Delaware Bay. The mineralogy of well-drained sandy beds from 12 sites in these three areas was com pared to ascertain compositional maturity (defined, for example, for clay-sized material as the presence of iron and aluminum oxides or hydrated silicates) in relation to the age of the formation containing the sand.