Geologic Evidence of Hurricane Katrina Recovered from the Pearl River Marsh, MS/LA

REESE, C.A.; STRANGE, T.P.; LYNCH, W.D., and LIU, K.B., 2008. Geologic evidence of Hurricane Katrina recovered from the Pearl River Marsh, MS/LA. Journal of Coastal Research, 24(6), 1601–1607. West Palm Beach (Florida), ISSN 0749-0208. Hurricane Katrina made its final landfall on August 29, 2005, as a category three storm, at the mouth of the Pearl River on the Mississippi/Louisiana border. Between October and December of 2005, 16 cores were recovered along two transects in the Pearl River Marsh: one running east to west across the mouth of the delta, and the other running south to north through the center of the basin. Loss-on-ignition and grain-size analysis clearly identified the sediments deposited by the storm and the resulting 5.9 m storm surge. The inorganic storm layer consisted of fine grain sands and silts, which were easily distinguished from the organic peat that develops naturally in the marsh. Although the Pearl River Marsh received uniform storm surge, the storm layer was unevenly distributed and was thicker and more pronounced toward the center of the marsh. The funneling of the storm surge by the floodplain terraces and/or the winnowing effect of wave action could account for this variability. Only 5 of the 16 cores showed evidence of Hurricane Camille, which made landfall near the Pearl River Marsh, as a category five storm, in 1969. Erosion and bioturbation of the marsh sediments could have worked to blur or even erase this layer in some locations, which would explain the inconsistent record. If this level of variability and degradation is common for marsh environments, it presents a challenge to paleotempestological investigations from these areas and emphasizes the importance of environmental reconstructions based on multiple transects of cores. ADDITIONAL INDEX WORDS: Firstword, next.