SUPERFÍCIES DE EROSÃO NO QUADRILÁTERO FERRÍFERO, MINAS GERAIS

Erosion surfaces in an area of faulted and folded relief are defined and localized in the Quadrilatero Ferrifero. The usual problems in delimiting the erosion surfaces are described. As a criterion, erosion levels are defined as reliefs of between 4 and 10% and controlled by spacial continuity and structural conditions. In identifying the areas of conserved relief, clearly separated from the dissected reliefs, the median is used instead of the mean. With this method a solution for the "cimeiras" surfaces in the Serra do Caraca was achieved, where neotectonic upheavals occured. The distribution pattern of contour lines for one generation of surfaces differs fundamentally from that of other generations. By the distinction of these patterns, lower levels are defined which are already controlled by the structures of great folds, principally in the synclines. By way of patterns and medians, the grade of surface coalescence is determined. A hierarchy of morphoclimactic processes is defined by the great variety of pediments with or without material. The formation of the erosive complexes of pediment-playas, elaborated independently and connected, is concluded in recent periods, by the opening of drainage and exorheism.