Coastal Geoheritage in Southern Brazil: Scientific Perspectives from the Northern Coastal Plain of Rio Grande do Sul

Abstract The northern sector of the Rio Grande do Sul Coastal Plain, southern Brazil, preserves a detailed record of Quaternary sea-level changes and coastal processes. In this study, 54 geosites were identified and characterized across 18 municipalities, including lagoon-barrier systems, dune fields, coastal ridges, abrasion caves, testimony hills, lagoons, spits, deltas, and shell mounds. These sites document the geological evolution of the region during the last 325,000 years and represent key elements for the reconstruction of paleoenvironments and coastal dynamics. The methodological approach combined cartographic and bibliographic surveys, GIS-based data integration, and fieldwork validation. Results indicate that several geosites have international relevance due to their representativeness, integrity, and rarity, while others provide significant opportunities for education and geotourism. However, many of these sites are located outside legally protected areas, which increases their vulnerability. The analysis emphasizes the importance of integrating geodiversity into conservation and management instruments, reinforcing the role of coastal features as archives of climate change and as providers of ecosystem services. The results provide a scientific basis for geoconservation strategies and support future initiatives, such as the proposal of a geopark focused on the lagoon-barrier systems of southern Brazil.