Grain size parameters for sandy-gravels

A series of parameters are proposed to describe the grain size frequency distribution of sandy-gravels. They are shown to be selective in distinguishing variations in the proportions of the two modes, especially at 25% sand, an important point in the packing of bimodal materials. A number of samples from the Solent, a channel between Hampshire, England, and the Isle of Wight, are considered as examples of the sedimentary significance of the use of the parameters in a tidal environment.