SUMMARYAlthough supplied to rivers, grains of about 1–6 mm diameters are notably deficient in fluvial deposits because they are more readily entrained and more rapidly transported than grains of larger or smaller size. Very coarse sand and fine gravel are rarely found in shallow‐water sediments for the same reason. Currents, mainly of wave origin, concentrate these grains in beaches, where they are present in more‐than‐ordinary ab