Erosive processes are very common in the northwest area of Parana State, in Caiua sandstone site. Processes such as: gullying, soil mass movements and losses of soils by runoff. Such processes are related to the pedological covering organization (structure) and its landuse. To research the genesis of such processes in headwater areas, where gullies frequently develop, it was chosen a local, partially preserved, landscape unit. The data collecting of pedological covering, through four soil topsequences, showed two types of slope morphology and that there's a specific pedological system associated to each slope. Above the source, slopes are convexo-concave, covered by dark reddish latosol - quartz sands - gley; the slopes directly related to the drainage axis are convex and they present a pedological system composed by dark reddish latosol - dark reddish podzolic soil - quartz sands. From upper to down slope, a superficial horizon of sandy texture thickens becoming a volume of about 2m of thickness (quartz sands) near the source. When vegetation is diminished, it facilitates the erosive processes and then, through regressive erosion, reaches the upper slope sections. In outlying suburbs, the erosive processes are set in drainage headwater because, besides the fragility of soils, pluvial waters of paved roads are concentrated and poured out overthere.