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Abstract Historical accounts suggest that Euro-American agricultural practices (post–1850 CE) accelerated soil erosion in the Paleozoic Plateau of the Upper Mississippi River Valley (USA). However, the magnitude of this change compared to longer-term Late Pleistocene rates is poorly constrained. Such context is necessary to assess how erosion rates under natural, high-magnitude climate and eco-geomorphic change compare against Euro-American agricultural erosion rates. We pair cosmogenic 10Be analyses and optically stimulated luminescence (OSL) ages from samples of alluvium to build a paleoerosion-rate chronology for Trout Creek in southeastern Minnesota (USA). Erosion rates and their associated integration periods are 0.069–0.073 mm yr−1 (32–20 ka), 0.049 mm yr−1 (28–14 ka), and 0.053 mm yr−1 (14–0 ka). Based on previous studies, we relate these rates to (1) the transition from forest to permafrost at the onset of the Last Glacial Maximum, (2) the decline of permafrost coupled with limited vegetation, and (3) climate warming and vegetation re-establishment. These pre-settlement erosion rates are 8× to 12× lower than Euro-American agricultural erosion rates previously quantified in the region. Despite a limited sample size, our observed rapid increase in erosion rates mirrors other sharply rising anthropogenic environmental impacts within the past several centuries. Our results demonstrate that agricultural erosion rates far exceed climate-induced erosion-rate magnitude and variability during the shift from the last glaciation into the Holocene. 

Abstract Alluvial rivers aggrade, incise, and adjust their sediment‐transport rates in response to changing sediment and water supply. Fluvial landforms, such as river terraces, and downstream stratigraphic archives may therefore record information about past environmental change. Using a physically based model describing sediment transport and long‐profile evolution of alluvial rivers, we explore how their responses to environmental change depend on distance downstream, forcing timescales, and whether sediment or water supply is varied. We show that amplitudes of aggradation and incision, and therefore the likelihood of terrace formation, are greater upstream and in shorter and/or wetter catchments. Aggradation and incision, and therefore terrace ages, may also lag behind environmental change. How sediment‐transport rates evolve depends strongly on whether water or sediment supply is varied. Diverse responses to environmental change could arise in natural alluvial valleys, controlled by their geometry and hydrology, with important implications for paleo‐environmental interpretations of fluvial archives. 

Abstract Landslides pose a major natural hazard, and heterogeneous conditions and limited data availability in the field make it difficult to connect mapped landslide inventories to the underlying mass-failure mechanics. To test and build predictive links between landslide observations and mechanics, we monitored 67.89 h of physical experiments in which an incising and laterally migrating river generated landslides by undercutting banks of moist sand. Using overhead photos (every 20 s) and 1-mm-resolution laser topographic scans (every 15–30 min), we quantified the area, width, length, depth, volume, and time of every visible landslide, as well as the scarp angles for those within 3 min prior to a topographic scan. Both the landslide area–frequency distribution and area–volume relationship are consistent with those from field data. Cohesive strength controlled the peak in landslide area–frequency distribution. These results provide experimental support for inverting landslide inventories to recover the mechanical properties of hillslopes, which can then be used to improve hazard predictions.