ABSTRACT
Return to kaolinite ƒ In northeastern wBrazil, the top kaolinite layer can be up to 10-m thick (Truckenbrodt et al. 1991). This is a sort of geochemical paradox. On the one hand, between the base and the middle of the profile, the kaolinite is destroyed and iron is concentrated. On the other hand, higher in the profile, it is the opposite, at least apparently: the cuirass is decomposed and kaolinite reappears, contradicting the idea of progressive desilication presented earlier. Various hypotheses have been put forth that, perhaps, should be considered to work in unison. (1) Role of termites. Termites bring up to the soil surface clays and
quartz grains extracted from the lithomarge. For these insects, it is a matter of rebuilding the termitaria destroyed by rain. They are capable of annually moving nearly 20 tonnes of soil per ha (Lavelle et al. 1992). It has been calculated that the mass of kaolinite found on the surface could have been brought up in a few thousand years.
