THE CONDITIONING FEATURES OF DITCHES PROCESSES AT THE SEDIMENTARY STRUCTURES OF THE PERIPHERAL DEPRESSION IN RIO GRANDE DO SUL

Abstract

Aiming to define the conditioning features responsible for the different erosionprocesses actuating at the drain heads between Jacuí and Ibicuí rivers - at PeripheralDepression in Rio Grande do Sul, we analysed the geologic/geomorphologic aspects defininga set of marks due to the relief evolution, in which the details are presented as interfluvialdepressions – pseudokarstic forms, rill erosion and large burrows, all of them interlaced to thehydrodynamic system. Based on a cartographic chart, satellite images, structural analysis ofthe sedimentary components and the examination of the hardness presented by severalsamples of water collected at, approximately, 15 and 48 meters deep, we verified theexistence of complex surface structures (approximately 30 meters deep) associated to theapparently simple topographic forms (hills with ample areas of captivation and long ramps),geological events as fault lines and the stratigraphic arrangement of the sedimentary materials.These are the predisposing elements of the erosion forms here analysed, showing that theorigin of these forms is beyond the anthropogenic action scale, becoming necessary therealization of systematic interconnected stratigraphic and surface geometry studies.

Keywords

• erosion factors
• burrows
• landscape evolution