The first delimitation will be obviously against granular or fine soils, which present a
high percentage of voids and thus a high deformability. They require the use of special
techniques different from the ones we will deal with hereafter.
But, also highly weathered rock masses like for example hydro-thermally altered
granite completely or partially turned to sand, or decomposed dykes, or completely
crushed zones in faults as well as highly porous rock lay outside of the field of our
discussion.