Geomorphology of the São Pedro ridge and Lower Piracicaba River region, southeastern Brazil

Abstract

ABSTRACTThis work presents a new geomorphological map (1:50,000) of the São Pedro region in southeastern Brazil. It incorporates new information about landform development and updates the classical legend of the Recherche Coopérative Sur Programme 77 that supported the previous map drawn in 1978. According to the new map and associated papers, tectonic structures have controlled the orientation of the streams that have dissected the regional landforms, especially during wetter periods. Under dry conditions, the planing process caused faster escarpment retreat of the São Pedro ridge and gave rise to a glacis and its Pleistocene colluvial sandy cover. The escarpment, glacis, and other regions were dissected during subsequent wet periods, forming the upper Quaternary main fluvial terraced levels of the Piracicaba and Tietê rivers. Finally, this geomorphological arrangement was disturbed by the reactivation of old structures in the current tectonic environment.