“PÉNICAUT’S STORM” – ALABAMA LAKE SEDIMENT PRESERVES FORGOTTEN CATASTROPHIC HURRICANE DISASTER

A storm layer identified in Lake Shelby, AL, a freshwater lake positioned only ~ 250 m from the Gulf shoreline, was deposited by a powerful hurricane in 1717 A.D. that changed the culture of the South. Known to historians as “Pénicaut’s Storm,” this catastrophic hurricane disaster severely damaged the French harbor and capital of French Louisiana at Mobile, AL. The extensive damage resulted in the movement of the French capital first to Pascagoula, MS and subsequently to New Orleans, LA. Storms were recognized in Lake Shelby sediment by shifts in stable isotopes (carbon and nitrogen) and percent organic material values that reflect marine influxes into the lake. The morphology, geochronology, and water chemistry attributes of the lake were constrained using sediment cores, seismic “chirp” data, radiocarbon dates, and water chemistry measurements. This new method is more robust than equating sand layers recognized in lake sediment as representing severe storms because the entire lake is surrounded by sand. The organic-rich sediment of Lake Shelby reveals an 800-year storm record for the Alabama coast. This data will add to the understanding of how severe storm frequency and intensity fluctuate relative to climate variations.