Abstract A shoreline rhythm was studied at Duck, North Carolina, during June of 1980 and 1981. The results of both studies show that the shoreline rhythm developed when small waves, approaching the shoreline at an oblique angle, rebuilt the beach following an erosional event; storm waves, on the other hand, eroded the rhythm. When the shore was being rebuilt, small waves and associated longshore currents reshaped the nearshore topography from a shoal to a longshore bar; one end of the bar became attached to the beach and in turn caused an increase in the horizontal distance between the tip of the horn and the adjacent bay of the rhythm (twice-amplitude). As more sediments were transported from the nearshore and deposited on the horn, twice-amplitude continued to increase. However, as the beach prograded at the horn, the beach located at adjacent bays did not rebuild nor was it eroded. Because rip currents were noted in bay regions of the rhythm, it is suggested that these currents prevented nearshore sediments from being transported and deposited on bay beaches. Thus, the increase of the rhythm amplitude was caused more by deposition occurring at the horn than of erosion taking place in the adjacent bays.