Bed Sediment Size

<<< 2 mm, not gritty = silt, mud M
< 2, gritty = sand S
2-8 = small gravel Gs
8-16 = large gravel Gl
16-32 = small pebbles Ps
32-64 = large pebbles Pl
64-256 = cobbles C
> 256 but discrete = boulder Bld
continuous = bedrock Br