Geological Society of America

23 D7. Quaternary Geology (Posters)

Sunday, 18 March 2018
1:30 PM - 5:30 PM
Lake Champlain Exhibition Hall

A RECORD OF EARLY HOLOCENE WILDFIRES AND 18-20TH CENTURY HUMAN IMPACTS IN AN UPLAND WETLAND IN EASTERN CONNECTICUT

Paper number: 23-16
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Caitlin T. McManimon Presenting Author
University of Connecticut, Storrs, CT
Kyle Farrell
University of Connecticut, Storrs, CT
Scott Rowan
University of Connecticut, Storrs, CT
Joseph Wilcox
University of Connecticut, Storrs, CT
Michael T. Hren
University of Connecticut, Storrs, CT
William B. Ouimet
University of Connecticut, Storrs, CT
Yulio Araya
University of Connecticut, Storrs, CT
Benjamin Lee
University of Connecticut, Storrs, CT
Liam Nangle
University of Connecticut, Storrs, CT
Heather Scofield
University of Connecticut, Storrs, CT
Billy Stansfield
University of Connecticut, Storrs, CT
Fernanda Mastroluca
University of Connecticut, Storrs, CT
Kervelle Baird
University of Connecticut, Storrs, CT

Abstract

Wetlands contain useful sedimentary archives of landscape processes through time. This study presents the results of a 9,000-year-old record of landscape change preserved in an upland wetland in eastern Connecticut. Two vibracores were collected from the edge of a moderately-sloped wetland at the base of Horsebarn Hill on the University of Connecticut’s campus. The Horsebarn Hill wetland (elevation ~180 m) is surrounded by a drumlin comprised of lodgement till, and is currently occupied by cattle for the university’s dairy farming. Vibracores were subsampled and analyzed for organic content via loss on ignition (LOI), grain size distribution, elemental composition via handheld x-ray fluorescence (XRF), bulk C/N ratios, and isotopic nitrogen (d¹⁵N) signatures. Core stratigraphy is dominated by woody peat and organic-rich sediment, with interbedded sand, gravel and organic layers towards the bottom (>2 m). The upper 30 cm contains coarse, sandy material situated above a long layer of organic, woody peat. d¹⁵N values shift from lighter to heavier values (0‰ to +3.0‰) near 40 cm depth, similar to values expected for manure and fertilizer. Heavy metal counts (Pb, Zn, Cu) increase around 30 cm and are higher than background signals. Together, we interpret the sedimentology, d¹⁵N values and heavy metal data in the upper 40 cm to reflect human activities from European settlement and intense pasture-style agriculture in the 18^th to early 20^th century, to industrialization in the 19^th and 20^th centuries. Sandy layers deeper in the cores (>2 m) are much older and often contain charcoal. One such layer, 310 cm below the surface of the wetland, contains 8 pieces of charcoal that were identified as White Oak and is radiocarbon dated to 8,900 +/- 100 years BP. We interpret this as strong evidence for early Holocene fires and associated runoff events in the region. Overall, the Holocene stratigraphy observed at Horsebarn Hill reflects a transition from early Holocene storminess to a stable climate and marsh environment, until a period of landscape modification at the onset of European settlement.

Geological Society of America Abstracts with Programs. Vol. 50, No. 2

doi: 10.1130/abs/2018NE-311337

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