Date of Award

Spring 2010

Document Type

Legacy Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Paul T. Gayes

Second Advisor

Jenna C. Hill

Third Advisor

Kehui (Kevin) Xu

Abstract

A prominent deposit of sand size sediment lying at an oblique angle to the shore lies off the coast of Long Bay, South Carolina. To determine the origin of this feature, geophysical data and core descriptions were compiled from previous studies. Microscopic analysis of glauconite, heavy minerals, and shell fragments, as well as observations of roundness, sorting, and foraminifera were also completed. From the data, three stratigraphic units were identified that correspond to three distinct environments: underlying seafloor, the mouth of an ebb tidal delta, and reworked overlying sediment. The environments indicate that the shore oblique sand body is a remnant of an ancient ebb tidal delta system. The formation of an ebb-delta is presented in a seven step conceptual model whereby during a time of lower sea level during the late Holocene, an inlet opened and deposited inland material on the shelf. The inlet moved laterally in response to longshore current and the underlying geologic framework. The inlet also landward in response to sea level rise. As a result the delta took on a shore oblique shape and fine grained material was deposited over the older delta deposits. Deposition continued until the tidal prism shrank and sediment bypassed to the shelf, stranding the delta deposit on the shelf. Over time, the inlet closed and the delta deposit was reworked by hydrodynamic processes. The proposed model is consisted with others, (e.g. Robinson and McBride 1991; Robinson and McBride 2007; Snedden et al 1999) that illustrate the formation of sand bodies within other sediment starved systems.

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