SALTATION ON GRAVEL BEACHES, TIERRA-DEL-FUEGO, ARGENTINA

Saltation is a common phenomenon on gravel beaches. Sediment traps acr oss two beaches of the El Paramo Spit (Tierra del Fuego, Argentina) yi elded different results on mean-grain size, sorting, saltating load, s hape and height above the bed. Mean-clast size increases with height a bove the bed to an altitude where the saltating size diminishes. The s orting of the saltating populations also increases until an altitude w here it begins to diminish. Spheres are preferentially set into saltat ion, although the bed is dominated by platy, bladed and elongated grav els. Much of the behavior of the saltation population is related to lo cal wave dynamics, beach steepness and stage of the tide. The processe s of gravel segregation (size and shape) on beaches obey to particular phenomena not considered in present-day sediment transport equations, but of much importance in relation to coastal defense improvements as dynamic revetments.