Coarse clastic barrier beaches: A discussion of the distinctive dynamic and morphosedimentary characteristics

Coarse clastic barriers are common on mid- and high-latitude coasts. They possess a morphosedimentary and dynamic distinctiveness which sets them apart from sandy fineclastic barrier forms. The reflective nature of the seaward barrier favors the development of zero mode, sub-harmonic edge waves particularly during long period swells (10–20 s), manifest in the formation of high level cusps. In some circumstances the pattern of recent overwashing of the barrier is related to cusps. Lack of distinct tidal passes, due partly to the high seepage potential of coarse barriers, means that very little sediment is transported seaward. Thus the barriers roll steadily onshore, and sections show a variety of washover facies, related to the volume of overwash surges.