Post Hurricane Heléne Rescue Operations at Shell Mound

by Lukas Desjardins, member of Friends' Board of Directors and UF graduate student of public archaeology

If you’ve visited Shell Mound recently, you have likely seen the effects of Hurricanes Helene and Milton which left behind piles of redeposited shell along the northern road and south ridge of the mound. Hurricanes are one of the greatest threats for archaeological sites in Florida, especially for coastal sites like Shell Mound. With climate change likely to increase the frequency and severity of hurricanes in the coming years, archaeologists are challenged with developing new ways to protect and manage these sites before they are destroyed forever.

Redeposited shell along the northern road

In early January, a team of archaeologists from the University of Florida led by Dr. Ken Sassaman began rescue operations on Shell Mound. This first stage focuses on the south ridge, along an escarpment where some of the most severe storm impacts were found. Here, storm surge from Hurricane Helene undercut the top of the mound, resulting in a collapse of the mound’s surface and redepositing shell all along the slope. Wrack from the storm surge was deposited nearly ten feet in elevation along the slope, and the remaining surface is highly unstable and likely to collapse in future storm events.

Escarpment on the south ridge with redeposited shell

Their first task involved excavating into the escarpment to create a flat vertical profile and remove shell which had been redeposited over the original surface. The excavated profile reached 180 centimeters in height. Based on the orientation of shells in the profile and changes in soil, the research team identified two possible pit features which may have been dug into the mound. Pit features such as these are valuable sources of archaeological information, and samples taken from one of the pits are pending analysis in UF’s Laboratory of Southeastern Archaeology.

UF Archaeologists excavating the escarpment

Sifting through the excavated materials, the archaeologists found indigenous pottery, the remains of fish, and tools constructed out of gastropod shells. Laboratory analysis of artifacts recovered from the damaged portion of Shell Mound has not been conducted yet, however analysis may provide additional information about the practice of oyster mariculture at Shell Mound and use of the site during winter months. Oysters harvested in the winter months are generally higher quality than those harvested in other parts of the year. In addition, the relative absence of oyster “lids”, the flat half of the shell, compared to “cups”, the rounded half of the shell, may indicate that oyster lids were returned to the neighboring reefs to sustain long-term oyster harvesting, while the cups were primarily used as a building material for the mound.

Excavated profile with possible archaeological features

In the spring, UF archaeologists will continue excavations from the original surface identified in this first stage of rescue operations. These excavations are likely to reach an additional two meters in depth, providing the deepest and most intact profile of Shell Mound to date which may reveal information about the origins and construction of Shell Mound. Following this second stage of excavations, the loose shell will be redeposited over the damaged areas in an attempt to stabilize the slope of the mound and mitigate the effects of future hurricanes.

In addition to on-the-ground research and stabilization, researchers from the GatorEye Unmanned Flying Laboratory have used drones to collect LiDAR data on the surface of Shell Mound following the 2024 hurricanes. LiDAR is a technology which uses laser scans to create three-dimensional models of the earth’s surface. Comparing this recent LiDAR data to data collected prior to the 2024 hurricane season will allow researchers to identify the extent of impacts from Hurricanes Helene and Milton, prioritize rescue work on areas showing the most severe impacts, and predict areas most likely to be impacted by future storms.

Hurricanes aren’t the only threat to Shell Mound, and human interventions can make the effects of storms worse. It is no coincidence that some of the most severe damage was along the northern road and south ridge, where the original slope of the mound was destroyed to make room for the road in the 1970s. If you visit Shell Mound, avoid walking on or near undercut surfaces, and be mindful around areas of exposed shell.