Particle size grain size Simple English Wikipedia the
Particle size also called grain size means the diameter of individual grains of sediment Very coarse gravel Pebble −4 to −5 16 32 mm in Coarse gravel Pebble −3 to −4 8 16 mm in Medium gravel Pebble −2 to −3 4 8 mm in Fine gravel Pebble −1 to −2 2 4 mm in Very fine gravel Granule 0 to −1 1 2 mm