Pleistocene Periglacial Processes and Landforms, Mid-Atlantic Region, Eastern United States

作者：Dorothy J. Merritts, Michael Rahnis · 发表于：Annual Review of Earth and Planetary Sciences · 年份：2022 · DOI：10.1146/annurev-earth-032320-102849 · 被引用次数：26 · 研究领域：Geology and Paleoclimatology Research、Climate change and permafrost、Methane Hydrates and Related Phenomena

Just as glaciers worldwide left a record of past advances and retreats that shifted latitudinally in response to oscillating Quaternary climate changes, so too have cold-climate conditions and permafrost left topographic and sedimentary signatures in former periglacial environments. This review documents widespread occurrence of past permafrost and intense frost action that led to rock fracturing, regolith production, and regolith-mantled slopes in the mid-Atlantic region of the United States during late Pleistocene cold-climate conditions. Strong signatures of thermal contraction cracking and brecciation from frost cracking exist where rocks and sediments are most frost susceptible, as with fissile shales. On sandstone hillslopes, frost weathering produced boulder-rich sediment that episodically flowed slowly down-slope during permafrost thaw, resulting in solifluction lobes and terraces in which colluvium moved cumulatively at least a kilometer. Radiocarbon dating, optically stimulated luminescence age control, and cosmogenic isotope studies constrain some periglacial features to the Last Glacial Maximum but also indicate longer residence times of regolith. ▪ Former permafrost and areas of intensive frost cracking extended over much of the mid-Atlantic region of the eastern United States during late Pleistocene cold glacial periods. ▪ Cold-climate conditions and permafrost left long-lasting topographic and sedimentary records with limited post-depositional erosion in the fo...