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The separate assessments of the fractions above and below 2000µm were combined using a spreadsheet conversion.
This followed a manual input of the dry sieve results for fractions 16-8mm, 8-4mm, 4-2mm and sub-2mm fractions and the electronic data captured by the Mastersizer below 2000µm.
This method defines the particle size distributions in terms of phi mean, median, fraction percentages (i.e. coarse sediments, sands and fines), sorting (mixture of sediment sizes) and skewness (weighting of sediment fractions above and below the mean sediment size; Folk 1954).
Graphic Mean (M) - a very valuable measure of average particle size in phi units (Folk & Ward, 1957).
Where M = The graphic mean particle size in phi
ø = the phi size of the 16th, 50th and 84th percentile of the sample