How do coastal dune ridges show that a coastline has grown seaward?

Coastal dune ridges serve as physical evidence of a coastline's seaward growth, a process known as progradation.1

This growth occurs as wind transports sediment from the beach in a landward direction, where it is deposited against obstructions. These small accumulations, known as coppice mounds, can develop into foredunes—the seaward-most line of dunes—provided there is a consistent supply of sediment and the beach remains free from destructive erosion.1

Many barrier-island or strand-plain coasts feature numerous, essentially parallel dune ridges that testify to this progressive seaward expansion. In these environments, the presence of multiple, successively younger dune belts—often separated by evidence of stabilized, vegetated surfaces—demonstrates that the coastline has advanced over time.12