Plow versus Ice Age: Erosion rate variability from glacial-interglacial climate change is an order of magnitude lower than agricultural erosion in the Upper Mississippi River Valley, USA

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 8x to 12x 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.