S
sand
yes
fine sand
no
coarse sand
Sg
N/A
Gs
hardbottom
Rs
very fine sand
medium sand
Gr
very coarse sand
Sr
Sm
coarse silt
Ms
mud
medium silt
Rg
R
granules
G
fine pebbles
Rm
Mr
M
Gm
fine silt
very fine silt
Mg
medium pebbles