Crossshore selective sorting processes and grain

Authors: D Hartmann

Publish Date: 1991

Volume: , Issue: , Pages: 49-63

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Abstract

Applying the population concept on more than a thousand beach sand samples from the southern Israeli Mediterranean coast allowed abandonment of the common single sample approach The study suggests six distinct grain size populations related to a sequence of six beach environments entitled 0 and 1 inshore 2 step 3 midswash zone 4 topswash zone 5 backshore 6 and D farbackshore wind blown sand and coastal dunes The invariant hyperbolic shape parameter Q indicates a gradual change of the grainsize distributional form across the left part of the hyperbolic shape triangle The shape positions χ ξ in the triangle suggest that the subaqueous populations are subjected mainly to erosiondeposition processes and move along one of the upper ’hammock’ curves in the shape triangle The subaerial populations were found to follow mainly ℵerosiondeposition processes and to move along the 06 to 07 Q lines However this group is divided into two basically different depositional environments waterlain backshore populations dominated by the swashbackwash bidirectional sheet flow and windblown sand originating from the backshore sediments The different grainsize populations reflect the sum of modes of transport which dictate the grain size cutoffs and the typical grain size thus defining the shape of the distributions

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