“Pans and potholes”: important features of the geomorphological heritage of the Guaritas geosite, Caçapava Unesco Global Geopark
DOI:
https://doi.org/10.21814/physisterrae.5563Keywords:
Weathering, Erosion, Geomorphology, Gnamma, Guaritas geositeAbstract
In Caçapava do Sul/RS, municipality whose limits coincide with those of the Caçapava UNESCO Global Geopark, the Guaritas geosite is a highly dissected plateau developed upon the early Paleozoic Guaritas Formation. That stratigraphic unit comprises cross-stratified, pebble-bearing sandstones, conglomeratic sandstones, true conglomerates, as well as subordinated siltstones. On horizontal, flat floorings and flat hilltops, as well as along some creeks, weathering and erosion “rock basin” features occur. In order to understand their evolution, bibliographic reviews, field trips, detailed remote sensing by drones, execution of 3D models and testing with a Schmidt hammer were performed. The first set of these features comprises shallow, irregular excavations, generally elliptical and elongated (resembling “platters” or “frying pans''), which are linked to chemical weathering (so referred to as weathering pans), where accumulated standing rainwater acts chemically on sandstones/conglomerates. The second group is composed by regular, cylindrical, deeper holes (pits or potholes), excavated into the rocks by physical weathering, normally at the headwaters of fluvial systems: the running and swirling water of these streams, together with the conglomerate clasts extracted from the rocks (pebbles and cobbles), provokes friction in the rock, leading to the deepening of potholes. Besides the obvious scientific and educational value, knowledge about weathering pans and abrasion potholes can increase the tourist content of trails within the geosite, in addition to contributing to the conservation of native fauna and flora species.
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Copyright (c) 2023 Felipe João Romansin, André Weissheimer de Borba, Anderson Augusto Volpato Sccoti, Felipe Guadagnin
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