Doctor of Philosophy (PhD)
Oceanography & Coastal Sciences
Reconstructing pre-historic hurricane activity is typically accomplished through the analysis of sandy overwash deposits identified in coastal lake settings. This method has been used successfully in many parts of the world and can extend the hurricane record thousands of years into the past. However, this approach also has its limitations. This dissertation addresses some of the limitations associated with geologic proxies used to reconstruct hurricane landfalls in the absence of historic data and tests new proxies for the identification of hurricane-derived overwash deposits. Modern storm deposits from two sites on the northern Gulf of Mexico coast are analyzed in detail to test methods for improving the interpretation of paleohurricane deposits and refining records of past hurricane activity. This research has three specific objectives: identify factors that affect the sensitivity of a site to record overwash deposits, determine whether two consecutive, visually indistinguishable overwash deposits can be differentiated from one another, and test organic geochemistry proxies for overwash deposit detection.
A detailed analysis of shoreline retreat at a coastal lake in Louisiana showed the site is progressively becoming more sensitive to hurricane impacts, which influences the way hurricane overwash events are recorded at that site. Changes in the geochemical composition of several sediment cores from this site also reflect this trend, and document changes in environmental conditions over the last century. Geochemical analyses were also successfully used to differentiate between two consecutive hurricane sedimentary layers, as well as highlight the importance of fluvial processes in storm-related sediment deposition. Analysis of sedimentary biomarker and stable isotope composition of overwash deposits from several sediment cores suggest that these proxies have potential for identifying hurricane deposits, vi but are likely greatly influenced by local factors that result in unique signatures at each site. The results from this research can be used to refine pre-historic hurricane reconstructions and improve the interpretations of hurricane deposits in the sedimentary record.
Dietz, Marianne Elizabeth, "A Multi-Proxy Approach to Refining Paleotempestology Records on the Northern Gulf of Mexico Coast" (2019). LSU Doctoral Dissertations. 4791.
Available for download on Tuesday, January 06, 2026