The size-garding of sand by wind

Abstract
In the course of experiments on the changes which take place in the size-grading of the grains when sands are picked up, transported and redeposited by a wind, it was found that by plotting the proportional weights of the constituent sieve-separated grades on a log scale, important changes can be observed in the character of the grading which are imperceptible when the usual grading diagram is used. Let the abscissa of the usual diagram be R = log diameter, so that δR is the log ratio between successive sieve apertures. If δp is the weight of a grade (total weight of sample unity), then ordinate ϕ = δp / δR . With an infinite number of sieves ϕ = dp / dR . The whole area included under the diagram is ∫ ϕ dR = 1. 1—The Grading Diagram Fig. 1 a shows the grading curve of a sample of dune sand, together with a suitably chosen “normal probability curve” ϕ' = a /√ π e - a 2 ( R - R 0 ) 2 where R 0 is log (most frequent diameter). Though comparison is difficult owing to the low values of the ordinates representing the extreme grades, it is some­times assumed that the grain-size distribution may be a random effect.

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