If it weren't for some interpretive signs, most visitors to Hilton Head Island's Sea Pines Forest Preserve would walk past the raised circle of ground between Lake Joe and Lake Thomas unaware it's a 4,000-year-old archaeological site.
One of some 50 known Native American shell rings found along the Southeast Coast, the Sea Pines Shell Ring is the most pristine - and accessible - example of these mysterious ancient middens. Most have been damaged by development, rising sea levels or erosion. The few that have escaped destruction are located on remote islands difficult to access.
Composed of hundreds of thousands of discarded oysters, clams, mussels and animal bones, the Sea Pines Shell Ring once stood two to three feet tall, stretching 150 feet across. Most of it is now covered in soil, making it barely distinguishable from the surrounding ground.
But for archaeologists, the undisturbed site could provide evidence that explains how the shell rings came to be.
A number of theories have been debated over the years. Some believe the rings were circular villages inhabited by Native Americans, who simply discarded the waste from their daily meals. Others think they were gathering spots for religious ceremonies, and the piles of shellfish the remains of large feasts.
A research team from New York's Binghamton University Anthropology Department has spent the last two summers studying the Sea Pines Shell Ring. A dig of the shell arc has revealed valuable information about the inhabitants' diet and lifestyle.
"We have found food remains from all four seasons, indicating that people lived at the site year-round," said Dr. Matthew Sanger, an assistant professor in the Department of Anthropology. "We also found evidence of religious ceremonies. We believe they may have hosted gatherings in the village on occasion."
The interior of the circle or "plaza" was kept remarkably clean. Last year, the team of graduate students led by Sanger found evidence of what appeared to be the corner of a house. When they return this summer, they'll dig near the same excavation pit to look for the rest of the structure.
Docents from the Coastal Discovery Museum will offer tours of the excavation site from June 4 to July 6 when the team will be working on the dig. The free tours will be offered from 9 a.m. to 3 p.m., Monday through Friday and some Saturdays.
Considered relatively small for a shell ring, the Sea Pines site probably supported 12 to 20 people, Sanger said. In comparison, shell rings found in Florida can reach 500 feet across and almost 15 feet tall, serving as home for 100 people.
Unlike shell mounds found in coastal zones all over the world, these were purposely planned to be circular. All of them date back between 3,000 and 5,000 years.
"You don't see this in other time periods," Sanger said. "They were constructed for a very limited time along the coastline of South Carolina, Georgia and Florida."
When they complete their research on the Sea Pines Shell Ring in the next few years, the Binghamton team will move north on the island to study Green's Shell Enclosure off Squire Pope Road near Skull Creek. It includes two shell rings connected to one another, Sanger said.