The Guaritas geosite of the Caçapava Aspiring Geopark in southernmost Brazil: geology, geomorphology, ecology and culture

The most important, internationally relevant geosite of the Caçapava Aspiring Geopark of southernmost Brazil is the Guaritas or Pedras das Guaritas geosite. That hilly area, with some 50 km², is located in the so-called Camaquã highlands, around the initial tracks of the Camaquã river watershed. The geosite has been developed upon a horizontal, heterogeneous package of fine- to coarse-grained, through-crossed sandstones, as well as pebble-bearing sandstones and minor lens-shaped beds of clast-supported, poorly sorted conglomerates. Those texturally and compositionally immature, red-coloured rocks of clear braided fluvial, continental origin, compose the type section for the Guaritas Group, the 300 meter-thick, uppermost unit of the Camaquã Basin, deposited in the Early Paleozoic (deposition from 530 to 500 Ma, diagenesis from 507 to 470 Ma). From a geomorphological point of view, the entire area is a deeply dissected plateau/tableland. The sedimentary package is cut by various sets of fractures, mainly striking NE-SW and NW-SE, and it displays classical ruin-shaped relief features. Landforms in the Guaritas geosite exhibit world-class examples (though still under-researched) of stress-controlled, discontinuity-related arcades, as well as diversified cavernous weathering features like tafoni and ledges. Lower relief zones, especially around water streams or upon flat, bare rock surfaces, show a profusion of weathering pits or gnammas, variously shaped and, sometimes, filled in with pebbles/cobbles. Such features not only substantially increase the geodiversity, rarity, and representativeness, as they also constitute a promising field of geomorphological (cavernous weathering) research in the Guaritas geosite and its vicinities. Besides its importance for geoscience, the ecological and cultural values of those residual hills are striking. A series of autochthonous, endangered species of cactuses, bromeliads, endemic flowers and bees find, in the Guaritas geosite, an ideal spot for survival and reproduction. The native shrublands and grasslands that surround the bare rock hills retain and preserve a unique, sustainable way of living, that of the family-based sheep and goat raising (“pecuária familiar”), practiced by people considered to be a traditional population of the Pampa of southernmost Brazil. The cultural importance of that hilly landscape is also embedded in the name of the geosite. While in other parts of the world, especially in Europe, such kind of landscape has been perceived as resembling “towns” or “villages”, in the southern Brazilian Pampa the cultural appropriation has been different. For that rural, military-based, warfare society, forged during the borderline battles opposing Portugal and Spain for their domains in South America, those hills resembled the bartizans or “guerites” (in Portuguese, “Guaritas”) of medieval to early-modern military fortifications. Today, the Guaritas hills are a synonym for scenic beauty, for traditional and sustainable landscape use and conservation, as well as for quality, nature-based activities. Hence, the Guaritas geosite relief profile is the key element of the Caçapava Aspiring Geopark logo, ideal for representing the territory, its origin, its identity, and its potential.