Coastal storm deposition; salt-marsh response to a severe extratropical storm, March 1993, west-central Florida

• Published in: Geology (Boulder) 1995-08, Vol.23 (8), p.679-682
• Main Authors: Goodbred, Jr, Hine, Albert C
• Format: Article
• Language: English
• Subjects: Atlantic Ocean; Brackish; coastal sedimentation; Florida; geologic hazards; Geology; Geomorphology; Gulf Coastal Plain; Gulf of Mexico; Hurricanes; landform evolution; Levy County Florida; Marine; marine transport; marshes; mires; nearshore sedimentation; North Atlantic; Oceanography; salt marshes; sedimentation; sedimentation rates; Sediments; shore features; Shorelines; storms; suspended materials; United States; Waccasassa Bay; west-central Florida
• ISSN: 0091-7613; 1943-2682
• DOI: 10.1130/0091-7613(1995)023<0679:CSDSMR>2.3.CO;2

On March 12-13, 1993, the passage of a severe extratropical storm, popularly referred to as the "Storm of the Century," resulted in the deposition of storm-suspended sediments along Florida's west-central coastline. In Waccasassa Bay, surge waters near 3 m in height inundated the coast and transported resuspended, nearshore sediments onto the open-marine marshes rimming the embayment. The thickness of the resulting storm deposit reached 12 cm on the levees and up to 2 cm on the marsh surface, and visible sedimentation occurred several hundred metres from the creek banks into the marsh interior. The tan to gray storm layer was composed of mixed clays, silt to very fine sand-sized quartz, and marine biogenic sediments, all similar to those of the underlying marsh sediments. Despite the evidence for severe storm conditions, this event was characterized further by the absence of shoreline erosion along the marsh coast. This condition contrasts with sandy coasts, where strong storms often result in shoreline erosion. As compared to sandy shorelines, the stability of this marsh-fronted coast is enhanced by the cohesive nature of the fine-grained marsh muds, baffling by the marsh-grass canopy, and sediment binding by plant-root matrices. Locally, the Waccasassa Bay coastal system has developed under sediment-poor, sand-starved, and low-energy conditions, and large-scale storm events may be an important component in sediment-transport processes and marsh-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 shoreline stability.