Constant action of tides, currents and waves brings continuous changes to the Severn's shoreline. Due to rising sea levels, waves have access to banks and cliffs, undercutting them and allowing sandy particles to be borne along and deposited at the mouths of creeks and coves. Sandbars form and occasionally extend across the mouth of a creek, creating a secluded tidal pond. During past interglacial periods, when sea levels were higher, bars were formed that remain today as high sandy promontories and hillside terraces. Although immense amounts of sand form these bars, the portions above water are usually small. Plants are quickly established here.
Saltmarsh cordgrass, hightide bush, poison ivy, trumpet vine, wild black cherry, black locust, dwarf sumac, and persimmon are typical, and eastern redcedar often assumes dominant proportions.