The origin and preservation of a major hurricane event bed in the northern Gulf of Mexico: Hurricane Camille, 1969

Abstract

Cores collected from Mississippi Sound, in the Gulf of Mexico, were studied using 210Pb xs and 137Cs geochronology, X-radiography, granulometry, and a multi-sensor core logger. Our results indicate the presence of a widespread sandy event layer that we attribute to Hurricane Camille (1969). An initial thickness of more than 10 cm is estimated from the cores, which is large compared to the time-averaged apparent accumulation rate of 0.29–0.47 cm y −1. Physical and biological post-depositional processes have reworked the sandy layer, producing a regional discontinuity and localized truncation, and resulting in an imperfect and biased record of sedimentary processes during the storm. The oceanographic and sedimentological processes that would have produced an event bed during Hurricane Camille are simulated using a series of numerical models, i.e. (1) a parametric cyclone wind model, (2) the SWAN third-generation wave model, (3) the ADCIRC 2D finite-element hydrodynamic model, and (4) a wave–current bottom boundary layer model that is coupled to transport and bed conservation equations (TRANS98). The simulated bed ranges from 5 cm to over 100 cm within a tidal channel near the barrier islands. Seaward of the islands, the bed is more than 10 cm in thickness with local variability. The magnitude and local variability of the storm bed thickness are consistent with the observed stratigraphy and geochronology on both the landward and seaward sides of the barriers.