Increased Erosion Rates Following the Onset of Pleistocene Periglaciation at Bear Meadows, Pennsylvania, USA

Abstract

AbstractDirect measurements of erosional response to past climate change are scarce, but mid‐latitude landscapes can record how shifts between cold and warm periods altered erosion outside glacial margins. To study hillslope responses to periglaciation, we measured bulk geochemistry and cosmogenic 10Be and 26Al concentrations in colluvium and weathered bedrock in an 18 m regolith core from Bear Meadows, Pennsylvania, ∼100 km south of maximum glacial extent. Using core lithology, cosmogenic nuclide concentrations, and regional 10Be‐derived erosion rates, we show the onset of 100‐Kyr glacial cycles at the Mid‐Pleistocene Transition (1.2–0.7 Ma) instigated multiple periglacial episodes in central Appalachia, increasing erosion rates compared to the relatively warmer Neogene. Our results show the higher efficiency of periglacial versus temperate erosion processes and highlight a pervasive Pleistocene periglacial erosion signal preserved in the 10Be inventory of surface sediments in central Appalachia, where erosion rates are slow enough to integrate previous cold‐climate processes.