DETERMINING IF AND HOW LAND USE DISTURBANCES AFFECT MILLENNIAL SCALE EROSION RATE IN THE APPALACHIAN PIEDMONT USING 10BE COSMOGENIC NUCLIDES

The southern Piedmont region of the Appalachian Mountains has been subjected to intense land use by European settlers in a setting of gradual topography, humid-temperate climate, and clay-rich soils. Starting in the late 1700’s and through the early 1900’s, native forests were cleared for timber and crops. Once land was wearied from overuse, it was abandoned with little vegetation. By the early 1900’s ~18 cm of soil eroded from the Calhoun Forest, South Carolina, creating massive gullies and clogging rivers and streams with sediment. By using in-situ produced ¹⁰Be cosmogenic nuclides in quartz grains, collected in Holcombe’s Branch stream and Tyger River, an average erosion rate will be modeled giving a better understanding of how human-induced landscape disturbance affects soil erosion on the millennial time scale. ¹⁰Be cosmogenic nuclide concentrations in quartz grains is directly proportional to the exposure age of cosmic rays. Quartz grains in the top ~1 meter of sediment not only represents exposure age, but the rate the soil is eroding due to hillslope transport processes. I will test the hypothesis that the apparent soil erosion rate in the Calhoun Forest, by measurement of ¹⁰Be cosmogenic nuclide isotopes and the universal soil loss equation, is greater than the soil erosion rate before European settlement. The ¹⁰Be isotopes are extracted from quartz grains through a series of quartz purification techniques and the isotopic ratio is determined by an Accelerated Mass Spectrometer. ¹⁰Be concentrations will be modeled using CRONUS online calculator and ArcMap software.