landwardprograding

Landward progradation is a coastal sedimentological process describing the net migration of depositional environments toward the land, rather than toward the sea. In this framework, shoreline and nearshore facies advance landward over time, resulting in an inland-ward thickening and extension of deposits such as deltas, beaches, and coastal plain sediments. The term is used in contrast to the more common seaward progradation, which describes shoreline advancement toward the open ocean.

The development of landward progradation typically requires a favorable balance of sediment supply and accommodation. High input of sediment from rivers or coastal erosion, combined with conditions that limit the expansion of accommodation space seaward (for example, tectonic uplift of the coast or relative sea-level stabilization), can drive deposits to accumulate inward. Climate, basin subsidence patterns, and tectonic setting influence the direction and rate of progradation, and the phenomenon is often discussed within sequence stratigraphy as part of regressive, landward-shifting depositional sequences.

Evidence for landward progradation is sought in stratigraphic records and geologic sections where coastal facies migrate inland through time. This can manifest as onshore thickening of deltaic or shoreface deposits, shifts in fossil assemblages toward inland sites, or seismic and outcrop geometries indicating inland-dipping facies belts. While not as widely recognized as seaward progradation, landward progradation is an observed pattern in certain sedimentary basins and coastal settings, reflecting the dynamic interplay of sediment supply, sea level, and tectonics.

See also: progradation, shoreline change, coastal stratigraphy, sequence stratigraphy.