Substrata of any origin where the substratum is composed of a mix of Hard and Soft
Substrata such that neither class is dominant (i.e. neither class comprises ≥ 80 % of the
substratum).
Substrata of any origin where the substratum is composed of a mix of Hard and Soft
Substrata such that neither class is dominant (i.e. neither class comprises ≥ 80 % of the
substratum).