A small hollow in a beach, U-shaped in plan; the arms pointing seawards. Beaches tend to have a series of cusps, formed when outgoing rip currents and incoming waves set up nearly circular water movements. They form by self-organization, wherein positive feedback between swash flow and the developing morphology initiates the development of the pattern, and negative feedback—from the circulation of flow within the beach cusps—causes pattern stabilization (Coco et al. (2003) J. Geophys. Res. 108, C3). Ciriano et al. (2005) J. Geophys. Res. Oceans 110, C02018 suggest that beach cusp evolution might control low-mode edge wave dynamics.
Subjects: Earth Sciences and Geography.