Holocene paleostorms identified by particle size signatures in lake sediments from the northeastern United States |
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| Authors: | Adam S Parris Paul R Bierman Anders J Noren Maarten A Prins Andrea Lini |
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| Institution: | (1) Geology Department, University of Vermont, Burlington, VT 05405, USA;(2) Present address: Department of Geology and Geophysics, Limnological Research Center, University of Minnesota, 500 Pillsbury Drive SE, Minneapolis, MN 55455, USA;(3) Faculty of Earth and Life Sciences, Department of Paleoclimatology and Geomorphology, Vrije Universiteit Amsterdam, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands;(4) Present address: San Francisco Bay Conservation and Development Commission, 50 California St., Suite 2600, San Francisco, CA 94111, USA |
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| Abstract: | The frequency and timing of Holocene paleofloods in the hilly terrain of New Hampshire and Maine are identified using 14C and high-resolution (cm-by-cm) particle size analysis of sediment cores taken from six post-glacial lakes (~0.1–1.4 km2). A total of nine sediment cores (4.5–6 m long) were taken near the base of stream delta foreslopes. End-member modeling
of the particle-size frequency distributions from each core produces 3–5 representative end member distributions, or end members
(EMs). Concurrent increases in mean and median particle size, and in the relative abundance of the coarsest EM(s), indicate
increased transport capacity of inflowing tributaries, resulting from rainstorms. In all 9 cores, particle size data show
clear signs of episodic, high-energy sediment transport events where proxy measurements such as loss-on-ignition and magnetic
susceptibility do not, demonstrating the sensitivity of particle size analysis in paleostorm investigations made using lake
sediment cores. Floods caused by storms in this region peaked around 1.4, 2.1, 3.0, 3.9, 6.8, 8.2, and 11.5 ka cal BP, and
presently appear to be increasing in frequency. Periods of storminess in New Hampshire and Maine correlate well with other
records of precipitation and climate in the northeastern United States during the Holocene, further supporting modern records
which show tropical air masses as a primary driver of extreme precipitation events in New England (Ludlum 1996; Konrad 2001; Sisson and Gyakum 2004). |
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