ABSTRACT
Soils are defined in two ways. Geologists and engineers see soils as soft, unconsolidated rocks. The entire profile of weathered rock and unconsolidated rock material, of whatever origin, is then soil material. By this definition, soil is the same as regolith, that is, ‘all surficial material above fresh bedrock’ (Ollier and Pain 1996:2). It includes in situ weathered rock (saprolite), disturbed weathered rock (residuum), transported surficial sediments, chemical products, topsoil, and a miscellany of other products, including volcanic ash.
