Introduction

This chapter covers some general comments on sieving, a method of sieve calibration, and some empirical studies on sieving analysis made by the Aarhus sand group. This group comprises geomorphologists, physicists, and statisticians, and the present study is part of a larger research project on the physics of windblown sand. The investigations presented here are focused on the effect of sieving in a set, the statistical variation in the sieving process, and calibration of a sieve set. The sieving procedure used by our group is described in the appendix. A general treatment of sieving analysis can be found in Ingram (1971), Allen (1981), and Kaye (1981).

Recent sedimentological studies call for a precise determination of the particle size distribution of small samples. Examples are small sediment samples from cores (McManus, 1965), studies of short-range variations in sand sorting (Barndorff-Nielsen et al., 1982), and sand collected in traps in wind tunnel and field experiments (Jensen et al., 1984; Sørensen, 1985). Furthermore, there is often a great variation in the amount of sand retained on the individual sieves in a set. For a well-sorted sand sample, the sieves representing the flanks of the distribution may well contain less than a thousandth of the weight in the sieves around the modal point. This has implications for the analysis because the sieving efficiency increases with a smaller sediment load on the sieve, whereas the coefficient of variation on the single sieve at repeated sieving grows with decreasing load.