Numerical chronology of Pleistocene coastal plain and valley development; extensive aggradation during glacial low sea-levels

An early post-Sangamon phase of deep entrenchment involved the Amite, Sabine, Neches, and the Pearl Valleys in Eowisconsin and early Wisconsin times. Except for the universal impact of the deep Last Glacial Maximum (LGM) entrenchment, the alluviation-incision cycles that produced two to four sets of terraces of aggradational and strath origin did not occur in all valleys synchronously and with identical effects. In certain valleys terrace aggradation coincided with the LGM record lowstand and the following late Wisconsin transgressive deglacial hemicycle. In contrast with intensive valley filling, inferred for the MIS 6 glacial interval, Holocene backfilling is far from complete in most late glacial entrenched valleys.