Soil classification (SBTn)

Zone number

(Robertson SBT 1990)

SBT Index values

Organic soils: peats

2

I_c > 3.60

Clays: silty clay to clay

3

2.95 < I_c < 3.60

Silt Mixtures: clayey silt to silt clay

4

2.60 < I_c < 2.95

Sand Mixtures: silty sand to sandy silt

5

2.05 < I_c < 2.60

Sands: clean sand to silty sand

6

1.31 < I_c < 2.05

Gravelly sand to dense sand

7

I_c < 1.31