Spatial and temporal variability of a coarse-sand anomaly on a sandy inner shelf,northeastern Gulf of Mexico

A 10-km² area of anomalously uniform coarse sand and low relief, in 30 m water depth off Panama City, Florida, USA, exists as a palimpsest hardbottom within the prevailing sand-wave system. Side-scan sonar observations over a ten-year period document the morphologic response of the anomaly to the bottom—wave—current interaction regime. The anomaly and surrounding sand waves remained fixed during this period. Ripples form within the anomaly in response to seasonal storms and decay during quiescent periods. Hurricane response includes minor realignment of sand waves, formation of megaripples, and deposition of a thin mud layer.