Testing the Unified Theory of Fragipan Genesis: Geomorphic Trends Between Fragipans, Eolian Affected Soils, and Periglacial Landscapes.

A new, more unifying hypothesis explaining the distribution of fragipans, and the genesis of the fragipan’s dominant morphologic characteristics postulates that fragipans are derived from a) a transported parent material that has density imparted to it via desiccation and consolidation (producing coarse prismatic structure); b) contains 30 – 70% silt, and approximately 5-35% clay; and c) that the deposit be all or in part derived from eolian sources. The importance of this new theory to other Geoscience fields is significant since the fragipan’s extent is intimately tied to eolian deposition. We present several examples from Pennsylvania, and the broader extent of the fragipan’s geographic range in the United States, demonstrating the use of this new model to explain fragipan absence or presence and the potential extent of late Wisconsinan eolian deposition in the United States.