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ABSTRACT: Historical Natural Shoreline Determination from Soil Borings and Sediment Analysis in Biloxi, Mississippi


State law in Mississippi stipulates that all lands naturally subject to tidal influence, up to the line of mean high tide, are public property, and any unnatural fill of these lands does not alter their public status. Natural accretion, however, does accrue to the adjacent property owner. An investigation of a suspected tidelands fill site in Back Bay of Biloxi revealed extensive artificial fill since 1817 when Mississippi was granted statehood. The Mississippi Office of Geology collected 29 soil borings and two vibracores at the site. Grain size analysis and sediment mineralogy were used to group the sediment types encountered according to probable depositional environment and source of origin.

The predominant sediment type found at the site is oyster shells, either whole or broken, or ground into a coarse sand size. The ground oyster shell material is inconsistent with natural material produced by wave action in the area. Based on historical archive research and grain size comparison with recent manufactured oyster shell products, the ground oyster shells (shell hash) were determined to be an artificial deposit, probably ground shell chicken grit, produced as a byproduct of oyster canning by a grinding mill at the site in the past. Many of the borings penetrated the Pleistocene substrate, indicating a definite natural surface at that depth. Numerous man-made artifacts in the borings aided in dating the time of placement of the sediment. Projecting current sea level onto the mapped base of artificial fill at the site revealed a natural historic shoreline landward of the present shoreline, resulting in additional state lands claimed. As a result of this study, the present property owners have agreed to a negotiated settlement of the boundary line, conceeding public ownership of a portion of the property.

AAPG Search and Discovery Article #90941©1997 GCAGS 47th Annual Meeting, New Orleans, Louisiana