A study on the genesis of humic Oxisols and its relationship with the evolution of the landscape was carried out in an area of 5,750 ha situated in the central segment of the South of Minas Gerais State. Two morphopedological systems (SMI and SMII), representative of the regional geology and geomorphology were chosen. Pedological (chemical, physical, morphological, micromorphological) and geomorphological studies, as well as soil charcoal quantification and radiocarbon dating were performed in four profiles classified as: Humic Xantic Hapludox and Typic Hapludox in SMI, and Humic Rhodic Hapludox and Rhodic Hapludox in SMII. The strongly developed umbric epipedons of the humic Oxisols are thought to be very old and have a continuous, progressive melanization with depth, probably deeply affected by charcoal fragments decomposition and its redistribution by soil fauna. Charcoal is more abundant in these oxisols than in others found elsewhere in the landscape. In situ soil formation in SMII suggest a great stability of the plateau where humic Oxisols are found.

This also suggest higher incidence of fires at this landscape position during the Quaternary, which can explain the higher soil charcoal content in the humic Oxisols. The occurrence of this kind of soils on the lower backslope and footslope of SMI indicate an important short-distance soil transport, probably as a consequence of substratum block tilting during Quaternary times. Fault mirrors in the saprolite and in the solum of one Oxisol, dramatic differences among charcoal datings between 125 and 150 cm of depth (from 6,850 to 40,000 years BP), as well as the seismic disturbances occurring at present in the area point to the role of resurgent tectonics in the evolution of the landscape. Thus, the humic Oxisols could be considered as relic paleosols and, as such, they would constitute a fundamental link to understand the dynamics of regional landscape.