Joint 56th Annual North-Central/ 71st Annual Southeastern Section Meeting - 2022

Paper No. 9-44
Presentation Time: 8:00 AM-12:00 PM


SHAW, Mason, HOLDER, Daniel, EADIE, Christian, MARQUAND, Sydney, LUDWICK, Trevor, ELGIN, Lauren, SIPE, W. Jay, DICKSON, Robin and LORD, Mark, Geosciences & Natural Resources, Western Carolina University, Cullowhee, NC 28723

This study examined legacy sediment deposits in the Cullowhee Creek floodplain located on the campus of Western Carolina University. Some regional studies have shown that the high intensity land use practices of European settlement increased rates of erosion and sedimentation (i.e., legacy sediments). The traits of legacy sediments, which began here around 1870, are only understood from a few studies, being an emerging topic of research. Further exploring the characteristics of legacy sediments in the area can help contribute to knowledge on the impacts of colonization in the Southern Blue Ridge Mountains.

The purpose of this study was to investigate the extent of legacy sediments within the Cullowhee floodplain. Also, where present, we sought to determine their characteristics and sedimentation rates in comparison to pre-legacy time periods. To answer these questions, 8 sites located in the floodplain were characterized for sediment texture and color, for elemental composition with XRF scans; and for dating by C14 of organic matter, presence of microplastics, and artifacts.

Results showed that legacy sediments are present within the entire length of the floodplain with thicknesses ranging from 50 to 120 cm and sand percentages ranging from 20 to 80 percent. Lower legacy sediments have a fining upwards sequence that is 30 to 90 cm thick. Some sites, are capped by a coarsening upwards sequence that is 5 to 25 cm thick. Elemental ratios in core sediments, like Al/Ti and Mg/Al, correlate with stratigraphic trends in the legacy sediments. Legacy sedimentation rates ranged from 3.5 to 12.5 mm/y; an order of magnitude greater than pre-colonial sedimentation. In a future study, we suggest to sample sediment profile sites at fine intervals along with more elemental characterization of the Cullowhee Creek floodplain. Also, other studies could investigate how modern land use practices effect erosion and sedimentation rates in comparison to legacy sediments.