Rip Currents: A Process of Geological Importance

Abstract

Rip currents are defined as seaward-moving streaks of water which return the water carried landward by waves. These currents are believed to be an almost universal accompaniment of large waves breaking on an exposed coast. Unlike the largely hypothetical undertow, rip currents flow principally at and near the surface. They attain velocities up to at least 2 miles an hour and extend on occasions for 1,000 feet or more from the shore. Geologically the currents are of importance, since they carry a suspended load of fine sediment out from the shore. Small channels in the sand are produced by the flow in the near-shore portions of the rip currents. The development and changes of these channels have been investigated. The strong outflow of the current and the presence of the channels along the bottom constitute a serious danger to inexperienced swimmers.