Shell ring

Shell rings are archaeological sites with curved shell middens completely or partially surrounding a clear space. The rings were sited next to estuaries that supported large populations of shellfish, usually oysters. Shell rings have been reported in several countries, including Colombia, Peru, Japan, and the southeastern United States. Archaeologists continue to debate the origins and use of shell rings.

Across what is now the southeastern United States, starting around 4000 BCE, people exploited wetland resources, creating large shell middens. Middens developed along rivers, but there is limited evidence of Archaic peoples along coastlines prior to 3000 BCE. Archaic sites on the coast may have been inundated by rising sea levels (one site in 15 to 20 feet of water off St. Lucie County, Florida has been dated to 2800 BCE). Starting around 3000 BCE evidence of large-scale exploitation of oysters appears. During the period 3000 BCE to 1000 BCE shell rings, large shell middens more or less surrounding open centers, developed along the coast of the Southeastern United States. These shell rings are numerous in South Carolina and Georgia, but are also found scattered around the Florida peninsula. Some sites also have sand or sand-and-shell mounds associated with shell rings. Sites such as Horr's Island, in southwest Florida, supported sizable mound-building communities year-round. Four shell and/or sand mounds on Horr's Island have been dated to between 4870 and 4270 Before Present (BP).

Groups living along the coast had become mostly sedentary by the Late Archaic period, living in permanent villages while making occasional foraging trips. Archaeologists have debated whether the shell rings resulted from the simple accumulation of middens in conjunction with circular villages, or if they were deliberately built as monuments. The start of mound building in the lower Mississippi River valley and in Florida by about 6000 years ago is cited as increasing the plausibility that the shell-rings were also monumental architecture. Excavations of the Fig Island rings revealed little evidence of habitation on the rings, and circumstantial evidence of rapid deposition of large quantities of shells in deliberate creation of the rings.

...
Wikipedia