Date of Award

Spring 1995

Document Type

Legacy Thesis

Degree Name

Bachelor of Science (BS)

Department

Marine Science

College

College of Science

First Advisor

Doug Nelson

Abstract/Description

Folly Beach has historically been a site of high erosion. The construction of the Charleston Harbor jetties by the Army Corps of Engineers in 1878 only exasperated the situation. But one particular location on the beach, known as the washout, undergoes a considerably higher rate of erosion. Seismic reflection profiles indicated a partly buried channel system occurred just off shore of this location. Fourier shape analysis was used on quartz sand grain samples to determine if the stratigraphic feature was affecting the offshore transport of sediment. Thirty-three samples of 400 grains each were digitized and then analyzed using Fourier analysis. Each sample was characterized by a harmonic amplitude frequency distribution and then submitted to an unmixing analysis. A four end-member solution was chosen for Harmonic 2, Harmonic 17-18, and Harmonic 20-21. The distribution of end-members within the samples was then interpreted. The size analysis, previously computed, was compared to the shape data. There appeared two patterns occurring offshore. On the west side of the channel system, sediment samples were smooth, elongated grains of the common size fraction. On the east side of the channel system, sediment samples were inconsistent in shape and size composition. However, the samples' shifts in compositions indicated a pattern. The channel system appears to sometimes sway in its course, causing a change in composition over time.

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