title: Frost for the trees: Did climate increase erosion in unglaciated landscapes during the late Pleistocene?
abstract: Understanding climatic influences on the rates and mechanisms of landscape erosion is an unresolved problem in Earth science that is important for quantifying soil formation rates, sediment and solute fluxes to oceans, and atmospheric CO2 regulation by silicate weathering. Glaciated landscapes record the erosional legacy of glacial intervals through moraine deposits and U-shaped valleys, whereas more widespread unglaciated hillslopes and rivers lack obvious climate signatures, hampering mechanistic theory for how climate sets fluxes and form. Today, periglacial processes in high-elevation settings promote vigorous bedrock-to-regolith conversion and regolith transport, but the extent to which frost processes shaped vast swaths of low- to moderate-elevation terrain during past climate regimes is not well established. By combining a mechanistic frost weathering model with a regional Last Glacial Maximum (LGM) climate reconstruction derived from a paleo-Earth System Model, paleovegetation data, and a paleoerosion archive, we propose that frost-driven sediment production was pervasive during the LGM in our unglaciated Pacific Northwest study site, coincident with a 2.5 times increase in erosion relative to modern rates. Our findings provide a novel framework to quantify how climate modulates sediment production over glacial-interglacial cycles in mid-latitude unglaciated terrain.
authors.affiliation: Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA. ; Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Jill A
authors.identifier: 0000-0002-2388-2072
authors.initials: JA
authors.lastname: Marshall
authors.affiliation: Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Roering
authors.affiliation: Department of Geography, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Patrick J
authors.identifier: 0000-0001-7657-5685
authors.initials: PJ
authors.lastname: Bartlein
authors.affiliation: Department of Geography, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Daniel G
authors.identifier: 0000-0001-8743-3949
authors.initials: DG
authors.lastname: Gavin
authors.affiliation: Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Darryl E
authors.initials: DE
authors.lastname: Granger
authors.affiliation: Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Alan W
authors.identifier: 0000-0001-6538-180X
authors.initials: AW
authors.lastname: Rempel
authors.affiliation: Department of Geography, University of Alabama, Tuscaloosa, AL 35487, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Praskievicz
authors.affiliation: School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: Tristram C
authors.initials: TC
authors.lastname: Hales
keywords: Climate; LGM; Paleoclimate; erosion; frost processes; frost-cracking; geomorphology; soil production