Size classes of flow-transverse bedforms in a subtidal environment,Nantucket Shoals,North American Atlantic shelf

The distribution and character of small-scale and mesoscale bedforms on the surface of a large tide-built sand ridge have been observed. Sand waves, class 1 and class 2 megaripples, and ripples are abundant. A histogram of bedform spacing is strongly bimodal, indicating that megaripples and sand waves comprise discrete populations. Ripples probably also comprise a discrete population, but the limit of resolution of the side-scan sonar system arbitrarily truncates the distribution; hence a third mode cannot be observed.