Cliff Erosion

Cliff erosion is the landward retreat of a coastal cliff under marine and subaerial attack. Waves undercut the base by hydraulic action, abrasion from entrained sediment, and quarrying along joints, cutting a notch that undermines the face until it fails. Subaerial processes, weathering, groundwater seepage, and freeze-thaw, weaken the rock between marine events, so retreat often comes as episodic collapses rather than steady wear. Retreat rates depend on lithology, from millimeters per year in hard rock to several meters per year in soft glacial till such as the Holderness coast. Rates rise with higher sea level and storm-tide frequency, threatening clifftop assets.