The alloterite, at the top of the saprolite, is a clayeyhorizon where, through volume reduction due to chemicalweathering and leaching, the structure of the parent rock islost. In plutonic rocks, the structure of the parent rock isstill identifiable at the top of the weathering profile, whichexplains that alloterites cannot be identified. In the underlyingisalterite, weathering only induces slight or nochange in volume thus preserving the rock structure.This layer forms half to two thirds of the thickness ofthe saprolite layer.