Abstract | A fragipan (Bxb horizon) encountered during the excavation of a multicomponent archaeological site buried on an alluvial terrace in central Pennsylvania was evaluated to determine the degree of development, pedostratigraphy, and age. Based on the horizon thickness, and the degree of development of adjacent horizons, we believe that the fragipan was weakly developed. Two to three buried A horizons (Ab) occurred within the Bxb, thus, the fragipan formed in a cumulative, or fluvent, type alluvial landscape and postdates the Ab horizons overprinted by it. The buried soils were associated with stratified cultural remains. Artifact and radiocarbon ages indicate that the fragipan formed in the last 4500 years. Fragipan-containing soils on alluvial terraces should be investigated for buried soils and associated stratified cultural remains overprinted by subsequent pedogenesis. © 1998 John Wiley & Sons, Inc.