How did rising sea level flood Pleistocene coastal environments?

During the transition from the Pleistocene to the Holocene, rising sea levels flooded coastal environments primarily through a process known as the Flandrian Transgression. As large ice sheets from the last glacial period melted, the resulting release of meltwater caused a global, or eustatic, rise in sea level.12

This process impacted coastal regions in several ways:

• Inundation of Lowlands: As sea levels rose, the water invaded former coastlands and low-lying areas that are now part of the continental shelves.31
• Formation of Estuaries: River valleys that were previously exposed to subaerial processes were drowned, transforming them into estuaries such as Chesapeake Bay and the Gironde Estuary.3
• Reworking of Sediments: In areas near former ice fronts, periglacial fluvial sands were extensively reworked by the advancing sea into beaches and bars.1
• Tectonic Complications: The flooding was not uniform globally. In regions formerly covered by ice, the Earth's crust responded to the removal of the ice load by rising, which in some places outpaced the sea-level rise, while other areas experienced subsidence, further altering the coastal landscape.1