Sedimentation and erosion during single tidal periods on two Long Island Sound beaches were recorded with colored sand. Deposits commonly were a lower, coarse-grained, poorly sorted, negatively skewed layer and an upper, finer-grained, better sorted, less negatively skewed layer. Exceptions were noted. Depths of erosion were 20-40 percent, or more, of breaker height. 'Breaker zone steps' developed with or without breakers. Pebble orientations (long axes) were 20-46 percent within 15 degrees of beach strike. Heavy mineral samples varied widely with hydraulic conditions and mixing of adjoining sand bodies.