A slope with a soil sequence over sandy Perm-Carboniferous sediments from the Itararé Formation with clayey oxidic soils was studied. This area is representative of the low hills with smooth relief of the low valley from the Piracicaba river. The area is located in the Piracicaba municipality about 22º 47'S & 47º 35'W within São Paulo State Peripheral Depression. The sequence comprises a clayey Dark-Red Latosol (Rhodudox), on the hill top transitioning downwards to a Dark-Red Latosolic-Podzolic Intergrade (Rhodic Kandiudox). At the upper backslope site there is an inclusion of a medium textured Red-Yellow Podzolic soil (Typic Hapludult). From general field observations plus the study of the local stratigraphy, macro and micromorphology and clay mineralogy of the six sampled pedons, it was concluded that the hypothetical soil material of the clayey soils is not all related to the underlying sediments. Evidences are for a strongly pre-weathered reworked parent material carried down from a clayey Neo-Cenozoic deposit whose similar remnants are under a nearby higher, almost flat, main interfluve surface. The oxic microaggregate characteristics of the backslope and footslope pedons were interpreted as inherited mostly from a similar parent material. On the lower upper third backslope there is a transition from an oxic like horizon to a kandic (argillic) one mainly due to clay lessivage over oxic microaggregates. This apparently produced coalescence of the older transported microaggregates. The hypothetical parent material of the Podzolic (Ultisol) median textured soil was interpreted as inherited from an old, now eroded, level of a river terrace alluvium from the Piracicaba river.
transition oxic; reworked parent material; slope deposits; soil landscape relationships; Itarare Formation