We document frequent, rapid, strong, millennial-scale paleovegetation shifts throughout the late Pleistocene, within a 100,000+. yr interval (~. 115-15. ka) of terrestrial sediments from the mid-Atlantic Region (MAR) of North America. High-resolution analyses of fossil pollen from one core locality revealed a continuously shifting sequence of thermally dependent forest assemblages, ranging between two endmembers: subtropical oak-tupelo-bald cypress-gum forest and high boreal spruce-pine forest. Sedimentary textural evidence indicates fluvial, paludal, and loess deposition, and paleosol formation, representing sequential freshwater to subaerial environments in which this record was deposited. Its total age-depth model, based on radiocarbon and optically stimulated luminescence ages, ranges from terrestrial oxygen isotope stages (OIS) 6 to 1. The particular core sub-interval presented here is correlative in trend and timing to that portion of the oxygen isotope sequence common among several Greenland ice cores: interstades GI2 to GI24 (≈. OIS2-5. d). This site thus provides the first evidence for an essentially complete series of 'Dansgaard-Oeschger' climate events in the MAR. These data reveal that the ~. 100,000. yr preceding the Late Glacial and Holocene in the MAR of North America were characterized by frequently and dynamically changing climate states, and by vegetation shifts that closely tracked the Greenland paleoclimate sequence.
Bibliographical noteFunding Information:
This work was funded by the U.S. Geological Survey Climate and Land Use Change Research and Development Program (Landscape Response to Quaternary Climate Change Project, M. Pavich). We gratefully acknowledge USGS drillers Eugene Cobbs, Jr., and Jeff Grey for coring assistance. We gratefully acknowledge the Fairfax County Park Authority (with special thanks to Kevin Monroe and David Lawlor) for coring permission and access to Huntley Meadows Park. We are indebted to Albert J. Froelich (USGS, deceased) for his insightful early geologic research in Hybla Valley. We thank Jack McGeehin (USGS) for AMS 14 C analyses of samples from these cores. We are grateful to Amy Myrbo, Kristina Brady, Anders Noren, and the staff at the Lacustrine Research Center at University of Minnesota-Twin Cities (Minneapolis), for their cooperation and technical support during initial splitting and processing of these cores. We thank Ben Hardt (USGS) for helpful discussion, and John Repetski (USGS), Christopher Bernhardt (USGS), Darrin L. Lowry (Univ.Delaware) and an anonymous journal reviewer, whose thoughtful reviews improved this manuscript. We acknowledge with special thanks GIS assistance from Gary R. Buell (USGS). We thank current and former staff of the Carnegie Museum of Natural History, Pittsburgh, PA (Mary R. Dawson, John E. Guilday (deceased), and Allen D. McCrady), for helpful early discussions on the temporal resolution of Pleistocene terrestrial sequences in eastern North America. Appendix 1
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- D-O events
- Frequency analysis
- Heinrich events
- Late Pleistocene
- Long climate record