| Concept definition: |
Very hard <SOIL> of <<SOIL_TYPE_USCS>> "well-graded gravel", "poorly-graded gravel", "silty gravel", "clayey gravel", "silty sand", "clayey sand", "lean clay", "silt", "organic silt", or "elastic silt", the <<SOIL_CONE_INDEX>> of which is about 280; type 9. |
