Geological history of Chesapeake Bay, USA

Abstract

Chesapeake Bay began to form as a partially enclosed coastal water body separated from the open ocean in the late Pliocene and developed through the Pleistocene and into the Holocene in response to coastal marine processes and major cycles of sea-level rise and fall. During times of emergence and low sea level, the rivers excavated channels in the broad coastal plain and subaerial processes eroded and modified existing landforms. During periods of high sea level, the Delmarva Peninsula lengthened as a major barrier spit, progressively enclosing what was to become Chesapeake Bay, and nearshore deposits of sediment accumulated along the western shore, enlarging the inter-river peninsulas. Highstands of sea level also resulted in the carving of regional scarps that mark the maximum shorelines. As the sea cycled back and forth across the coastal plain and continental shelf, a series of thin strata were deposited, then modified. The bay as it exists today may be at an end stage in the progression as the bay mouth has begun to function as a tidal inlet.