摘要：Frequent surveys using modern remote sensing technology enable observations of subaerial beach morphology and surface sediment type (sand vs. gravel/cobble) with unprecedented spatial and temporal resolution. Here we show weekly terrestrial mobile light detection and ranging (LiDAR) observations of cusps on a mixed sediment beach, consisting of sand and gravel/cobble, spanning ∼2 km alongshore. Surface gravel/cobble coverage varied from almost complete to none (e.g., all sand), over times ranging from weekly to seasonal, and with location. Cusp morphologies also varied in space and time. Cusps with 11–20 m alongshore wavelengths ( L ) primarily developed in winter and were composite with gravel‐cobble horns and sandy bays. Cusps with L between 21 and 40 m developed throughout the year and were either composite or entirely sandy. Previously not reported, composite mega cusps ( L between 200 and 400 m) occurred in winter. Composite cusps, with L between 11 and 40 m, were clustered in gravel/cobble‐rich mega cusp bays and absent on the sandier mega cusp horns. Plain Language Abstract Improved understanding of beach morphology is needed for coastal planning and hazard mitigation. Using remote sensing‐based survey technology, this study describes about 1 year of weekly observations of cusps, semicircular alongshore rhythmic patterns, along an ∼2 km beach consisting of sands and larger grain size sediments (gravels and cobbles). Cusp shape (e.g., horizontal and vertical undulations), alongshore rhythmic spacing patterns, and surface sediment types varied in space and time. The observation revealed previously unreported, composite mega cusps with rhythmic 200–400 m spacing and surface sediment zonations (sand versus gravel/cobble). The results highlight the potential of repeated surveys with modern remote sensing technology to explore the highly dynamic and complex behavior of mixed sediment beach morphology.
