Although the effects of shape and roughness on particle settling velocity are broadly understood, settling velocities of biogenic particles that have the quality of grain-size dependent roughness are less well constrained. This work by Joshi et al. addresses that gap in knowledge by examining the properties of maërls. The results indicate that maërl is suspended at lower current speeds than equant sediment, and how unsorted siliciclastic and maërl sediment can be advected differentially to deposit unsorted maërl gravel and fine sand. These results reveal how the hydrodynamic behavior of maërl may explain its propensity to form spatially well-defined "beds" or beaches with very low amounts of sand.
Settling velocity and grain shape of maërl biogenic gravel by Siddhi Joshi, Garret P. Duffy, and Colin Brown