d50

Channel median sediment size

The table below lists the D50 values of different sediment classes:

Sediment class	Size [µm]	Approximate size
Boulders	> 256,000	> Volley ball
Cobbles	> 64,000	> Tennis ball
Pebbles	> 2,000	> Match Head
Coarse Sand	1,500
Medium Sand	375
Fine Sand	94
Coarse Silt	47
Medium Silt	11.7	Not visible to the human eye
Fine Silt	4.9
Clay	1.95