A grain-size distribution is a laboratory measurement of the mineral component of an unconsolidated sediment sample. Many different methods provide quantitative measures of the relative abundance of different grain-size fractions. Examples are analysis of gravel (fractions between 2 mm and 63 mm) through sieving, and analysis of clay, silt and sand (fractions less than 2 mm) through laser diffraction. In this latter method, the intensity of light scattered by particles provides information about the grain-size distribution of the measured sample. The results of a grain-size distribution is usually shown in a table, either with percentages of the individual fractions or as a cumulative distribution.
Grain-size distribution on the map
Grain-size distribution can be found on the map under Subsurface research, sub-headings Geological borehole research and Seabed subsurface research.