22 Sediments, Sedimentation, & Stratigraphy (Posters)
THE INCISION OF THE JAMES RIVER CAN WEATHERED RIVER DEPOSITS DETERMINE THE HISTORY OF EROSION
Paper number: 22-1
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM
Authors
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Kat TelfeyanWashington and Lee University, Lexington, VA
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David HarborWashington and Lee Univ, Lexington, VA
Abstract
Our study examined the weathering of terraces of the James River to assess its evolutionary history. Two end-member models can explain the evolution of the river profile and the creation of river terraces from former floodplains: river terraces of similar elevation above the river were made at one time as the river cut vertically, or these terraces were caused by the propagation of a knickpoint due to a wave of incision working its way upstream (which makes the terraces increasingly younger age upstream). To correlate them we used a variety of analytical tools that included high powered spectrometry to global positioning system devices. We studied the weathering of soils on a suite of increasingly aged terraces in one location to apply it to a single terrace through space. We used ionically coupled plasma scanners (ICP), scanning electron microscope (SEM), and x-ray diffraction (XRD). To evaluate relative age we used a weathering scheme to give quartz grains from terrace soils a weighted weathered index. To account for clay and silt particle sizes we used a hydrometer analysis of soil samples.