COASTAL STORM DEPOSITION - SALT-MARSH RESPONSE TO A SEVERE EXTRATROPICAL STORM, MARCH 1993, WEST-CENTRAL FLORIDA

On March 12-13, 1993, the passage of a severe extratropical storm, pop ularly referred to as the ''Storm of the Century,'' resulted in the de position of storm-suspended sediments along Florida's west-central coa stline. In Waccasassa Bay, surge waters near 3 m in height inundated t he coast and transported resuspended, near-shore sediments onto the op en-marine marshes rimming the embayment. The thickness of the resultin g storm deposit reached 12 cm on the levees and up to 2 cm on the mars h surface, and visible sedimentation occurred several hundred metres f rom the creek banks into the marsh interior. The tan to gray storm lay er was composed of mixed clays, silt to very fine sand-sized quartz, a nd marine biogenic sediments, all similar to those of the underlying m arsh sediments. Despite the evidence for severe storm conditions, this event was characterized further by the absence of shoreline erosion a long the marsh coast. This condition contrasts with sandy coasts, wher e strong storms often result in shoreline erosion. As compared to sand y shorelines, the stability of this marsh-fronted coast is enhanced by the cohesive nature of the fine-grained marsh muds, baffling by the m arsh-grass canopy, and sediment binding by plant-root matrices. Locall y, the Waccasassa Bay coastal system has developed under sediment-poor , sand-starved, and low-energy conditions, and large-scale storm event s may be an important component in sediment-transport processes and ma rsh-surface accumulation. The response of the Waccasassa Bay system to this event offers a different view of storm-related shoreline effects and, in particular, the role that storms may play in long-term shorel ine stability.