Latin American Geomorphology

The Central and South American regions present diverse environments, landforms, and geomorphic processes that result from different processes produced in diverse climates, including equatorial, tropical, subtropical, temperate, and cold climates. These varied conditions have resulted in complex interactions among tectonic, climatic, and biotic factors, resulting in a wide array of landscapes. In this book, young geomorphologists from Central and South American countries present their research findings, showcasing the exciting topics and methods currently used in the field, presented during the 1st first webinar organized by the International Association of Geomorphologists in 2021. This research highlights the impact of endogenic forces, climatic events, and anthropic influences on the region’s geomorphic processes and the potential for planetary geomorphology and remote sensing techniques to contribute to the field. This book emphasizes the importance of studying geomorphology to understand the region's history, evolution, and current dynamics to inspire scientists and contribute to active geomorphology in Central and South America.

The Magallanes-Fagnano Fault System (MFFS) is the most important Quaternary structure in the Southern Andes. This transform system between the Scotia and South American plates extends over >600 km from the Atlantic Ocean to the Pacific Ocean and crosses Tierra del Fuego from W to E. This chapter is based on the analysis of satellite imagery and digital elevation models in combination with reconnaissance flights and field observations. Fieldwork includes validation of remote mapping along with reconnaissance, classification, and the identification of landforms and morphostructural features in selected areas. The geomorphological observations and the morphostructural analysis presented in this chapter argue that the MFFS generated ruptures and co-seismic displacements associated with the latest seismic events of 1949, among other episodes. This neotectonic evidence not only confirms the MFFS as the main potential seismogenic source for Tierra del Fuego but also shows the neotectonic influence on the transform boundary and demonstrates its impact on the landforms and landscape of Tierra del Fuego.

In the high mountain range of the Elqui Province, Chile, a landscape dominated by glacial and periglacial processes is recognizable. Glaciers have been identified as potential water reservoirs, although their dynamics and hydrological contribution have not been fully understood. Therefore, the study of these landforms becomes relevant to generate sustainable policies for the management of these potential water resources. Here, the volumetric variation of two rock glaciers in the basin of the Río Cochiguás for the period 1956–2018 is quantified, in order to establish the influence of geomorphological evolution, climatic variations and their possible hydrological implications to the watershed. A geomorphological map of the area was made. Topographic data were taken using differential GPS and a characterization of their detrital cover was developed. With this, it was possible to compare the volumes of the rock glaciers over time by comparing the current topography with surfaces reconstructed from aerial photographs of 1956 and 2000 of the same area. Glacial and periglacial landforms, cryogenic features among other geomorphic features were identified through the mapping. Some glacial landforms exhibit evident cryogenic features such as selection by freezing, slight grooves and superficial ridges and furrows, and a steep lateral slope composed of finer material. Valley-bottom rock glaciers, protalus lobes, gelifluxion slopes and avalanche deposits were also identified. The debris cover of the rock glaciers was conditioned by the high degree of weathering of the source outcrops. In addition, the angle of the frontal slope of these landforms is greater than the angle of repose, and they exhibit some surface features as ridges and furrows. These features indicate that these bodies are active, and that physical weathering processes play an important role in their dynamics. The comparison of rock glacier volumes indicated considerable changes, given the decrease in precipitation and the increase in temperature in recent years in the area, which would have a direct impact on freshwater reserves for the region.

Since the 1970s, the intensification of anthropogenic activities in the surrounding plateau has caused changes in surface processes that directly influence the fluvial dynamics of the Pantanal. As a consequence of these changes, the intensification of avulsion processes and increases in the magnitude of floods in the lowlands is observed, causing severe environmental and socioeconomic damage. Therefore, considering the ecological importance of the Pantanal and the changes that the basin has been suffering, there is a need to understand past and current conditions on fluvial behavior and how anthropogenic impacts on the plateaus have affected the lowlands. Here we propose to evaluate the response of the Taquari River to the human effects on its upper course in the last 50 years. Our approach uses satellite images to estimate suspended sediment concentration and quantify morphological changes in the channel. The results obtained demonstrate that the impacts resulting from deforestation in the plateau interfere with the water discharge and sediment load along the river course. With the increase in cultivation and pasture and suppression of natural vegetation, there was an increase in production and sediment transport (soil erosion) in the basin, altering the river's dynamic, structure, and functioning. Thus, the response of water discharge and suspended sediments was rapid and synchronous with land use changes. However, the river bar response time was slower, with the most significant increase in bars occurring around 10–20 years after the peak of deforestation rates. Changes in channel width and migration rates were insignificant, suggesting that these parameters have greater resilience or longer response time. The information obtained here provides new data to predict anthropogenic effects on the river system and support plans for conservation.

Tropical cyclones have provoked intense devastation over the last decades, and societal drivers such as unplanned urbanization and the lack of flood risk assessment have worsened the problem. Landslides and floods constitute a frequent hazard linked to tropical cyclones. This is not the exception in Costa Rica, where hydrometeorological disasters sum more than 90% of the total. Different climatic change scenarios indicate that a large number and more strong tropical cyclones will affect the North Atlantic Ocean Basin, where Central America and the Caribbean Sea lie. This study comprises different methodologies to understand the geomorphic effects of tropical cyclones in Costa Rica. This chapter presents geomorphological, hydrological, dendrochronological, and risk assessment approaches that aim to reduce the human and economic impact of tropical cyclones. Finally, the chapter calls for applying geomorphic assessments to elucidate the endogenic and exogenic processes controlling the effects of tropical cyclones in low latitudes.

Geomorphology as a discipline has extended its horizons to reach other celestial bodies. Planets, dwarf planets, moons, and asteroids can be studied by applying the same geomorphological premises. Through indirect information, planetary surfaces can be interpreted in a comparative way, applying the principles of terrestrial geomorphology to other planets but taking into account the physical properties of each planet. Nevertheless, some caution must be taken since a similar landform can have different origins on different planets. Mars has several geomorphic features that might be related with seasonal changes and liquid water/ice interaction. In this chapter, we make use of the MarsLux code to investigate changes in illumination conditions and relate the illumination and insolation maps with different landforms. For example, we could relate the resulting maps with cycles of freezing and thawing on the Martian surface. Also, by generating maps of illumination over one Martian year, we can relate the location of certain features with specific areas that receive an anomalous amount of solar energy. We present a tool that can connect an illumination analysis, from orbital parameters, with changes in insolation over geologically recent times and geomorphological evidence that points to the presence of subsurface ice, or alternatively to the thermal weathering of rocks.