ABSTRACT
We now have the materials for reorganizing the points made in Chapters 5 and 6 in the more general framework of the weathering-front model. Let us return to the Kosselili sequence and diagrammatically represent its three principal stages from the topslope to the footslope (Fig. 6.12) keeping in mind the general scheme of desilication (Chap. 3, Fig. 3.9). The Vertisol that is on the footslope of the sequence has undergone only the passing of the bisiallitization front (F1). The Solonetz, higher up the slope, exhibits the passage of F1 and, at the same time, that of the monosiallitization front F2. In the Lixisol at the topslope, F2 has caught up with F1. In practical terms, smectite either does not form or has an ephemeral existence.
