Turtle Mound, the tallest shell mound in the mainland United States, is an example of what it looks like when proactive measures are taken to preserve and monitor a coastal mound. But for this mound and hundreds of Indigenous cultural sites in Florida, archeologists are asking how long they can race against erosion.
This story was funded by the Delores Barr Weaver Legacy Fund at The Community Foundation for Northeast Florida.
On Florida’s East Coast at Cape Canaveral National Seashore, a thin stretch of land covered in jungle-like tropical vegetation cuts between the Atlantic Ocean and Mosquito Bay, moving with the coastal breeze like a single connected, living organism. Its flatness is punctuated seemingly by mountains—an unusual site in Florida. But these aren’t mountains. These are Indigenous mounds, including the dome-shaped Turtle Mound that juts into the bay and reaches 37 feet high.
Sea level rise threatens hundreds of Indigenous cultural sites along Florida’s coast, including mounds. As Turtle Mound erodes, it threatens its nearby sister mound sites: Ross Hammock, Castle Windy, and Seminole Rest. But some mounds in Florida and further north along the East Coast are eroding faster than archaeologists can document them. Unlike cultural sites that can be moved to higher ground, it’s impossible to move intact mounds. While efforts can be made to preserve them, the question is, for how long?
“You know, we can’t save everything, and what goes away goes away,” said Emily Jane Murray, public archaeology coordinator for the Florida Public Archaeology Network, who added that in some cases, the best option for saving archaeological sites is to fully excavate them before they succumb to sea level rise, which preserves data but also destroys the site.
Turtle Mound is the tallest shell mound in the mainland United States and may be the tallest in North America. Florida archaeologists generally accept that it was built between 800 and 1400 CE by the Timucua as they disposed of clam and oyster shells. They may have also used it as a navigational aid and a high vantage point to keep watch of the waterways.
This cultural site is an example of what efforts look like when proactive measures are taken to preserve and monitor a coastal mound, Murray says. The National Park Service works with FPAN at Turtle Mound to document changes, and preservation efforts are designed based on monitoring data to make the shore more resilient to sea level rise. Experts say similar efforts to protect other coastal mounds in Florida depend on funding, private landowners, legislation, and partnerships with Native American tribes.
How long Florida’s coastal mounds will last vary depending on factors like their location and the materials used to build them. The mentality among many archaeologists, Murray says, is to document as much as possible while they’re still here and monitor the progression of sea level rise impacts so experts can gauge the threat posed to individual mounds. Through monitoring, experts can track which mounds are holding up well, those that need help, and, in some instances, determine those that are too far gone.
Volunteers with FPAN’s Heritage Monitoring Scouts, a citizen science program that trains the public to monitor archaeological and cultural heritage resources, collect information from Turtle Mound to understand erosion occurring at the site and to form a snapshot of the mound’s condition, Murray says.
The NPS has collected data from the ground and air to verify erosion at Turtle Mound and three other threatened mounds at Cape Canaveral National Seashore. Archaeologists use conservation-minded stabilization techniques, including living shorelines and planted cordgrass and mangroves in the intertidal zone to bolster the coastline. Murray said there is evidence that these preservation efforts have staved off hurricane damage and lessened erosion.
Turtle Mound benefits from its management by the NPS and visibility as a tourist attraction at a national park. While many well-known sites are publicly owned, most archaeological sites in Florida sit on privately owned land, are little-known, and are often left at the mercy of landowner decisions due to lax laws and little oversight, said archaeologist Elaine Williams, member and former president of the Indian River Anthropological Society in Brevard County, which shares Cape Canaveral National Seashore with Volusia County.
Florida’s Unmarked Burial Law protects burial mounds and other Indigenous graves. However, while protection for Indigenous cultural sites on private property is encouraged through incentives like tax breaks, legal protection for sites on private land is limited in the state for mounds that were not intended for burials, Williams says. In Brevard, this creates complicated situations in a cultural resource-rich county where Indigenous people have lived for more than 11,000 years.
“We have good evidence that human beings were here at the same time as the giant Pleistocene megafauna—your mammoths and mastodons, giant ground sloths, and all that were here,” Williams said.
While protection for Indigenous sites in Florida has improved since mounds were destroyed and their materials used for roadfill more than a century ago, known threats to coastal mounds like looting, a lack of protection, and development are now paired with erosion from sea level rise, Williams says.
“I have seen plenty of erosion on the Indian River and the Banana River, and I have seen Native American sites eroding into the river,” Williams said. In many instances, she says, the goal is to document sites before they disappear: “You can’t stop it, you can’t change it. So, you simply record what you see.”
What happens when a mound is too eroded for preservation efforts to work? Murray says Florida can look to South Carolina’s shell ring mounds on Pockoy Island. Archaeologists are excavating the eroding site before it vanishes into the Atlantic, though it’s sliding into the sea faster than they can salvage some artifacts. Monitoring by the Heritage Monitoring Scouts and FPAN, which consults with Native American tribes in Florida, is helping state and federal managers of cultural heritage sites like Turtle Mound fight against that fate. Still, they won’t be able to save everything.
“We have a lot of conversations in our circles of folks working on these climate crisis issues, and you know, there’s a lot of burnout that happens, and you have to spend some time on self-care because it is kind of depressing,” Murray said.
Members of the Seminole Tribe of Florida are the living descendants of the Timucua and Calusa, who built many of central Florida’s Indigenous mounds. There are mixed feelings among the tribe about excavating cultural sites eroding as sea level rises. The majority opinion is that if nature is taking something away, it’s for the best, said archaeologist David Scheidecker with the Seminole Tribe.
The tribe prefers efforts to preserve coastal sites rather than excavate them, like the monitoring and erosion-prevention methods implemented at Turtle Mound. Of course, he said it’s understood that not all coastal mounds sites in Florida will be saved as they encounter sea level rise. Situations may occur where archaeologists recommend excavating eroding sites. “The main thing we want is for them to do their work and planning in consultation with the tribe,” Scheidecker said.
He said that a lack of state funding to preserve Indigenous cultural history could hinder the conservation of coastal sites.
“Prioritization of Native interests is not something that the country has been historically good on. The state of Florida has not been historically good in that regard,” Scheidecker said. “And to be frank, we’ve got a current administration in Tallahassee that’s trying to whitewash Florida history. So, they definitely don’t have interest in keeping anything that shows that there was native occupation before America showed up.”
However, with the appointment of Deb Haaland as U.S. Secretary of the Interior (the first Native American to hold the position), he said, “We’re seeing more funding coming for things like that, but it’s one very uphill battle.”
While the future remains uncertain, today, Turtle Mound rests tall on Mosquito Bay—a little shorter than it once was—as it has through centuries of storms, wars, and the development of Florida’s coastline. Still, this century may be its most precarious.
Stephenie Livingston is freelance science journalist and writer from rural north Florida. She joined The Marjorie as a staff writer in 2022. She has a B.A. in history and an M.A. in mass communications from the University of Florida. She’s reported for publications including Scientific American, Science, and Hakai Magazine.
This story was produced in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative founded by the Miami Herald, the South Florida Sun Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media, and the Tampa Bay Times. The Marjorie is a proud member.