The site, where the Jupiter lighthouse is now, also may mark the oldest known British settlement in South Florida.
Archaeologists have revealed evidence of a pre-Revolutionary War English settlement at the current site of the Jupiter lighthouse.
If confirmed by further research, the mysterious hamlet would be the oldest British settlement discovered in South Florida. It even could be the legendary, lost Grenville Plantation, scientists said, and could date to 1763.
"Part of the challenge now is to sort through the rest of the evidence," said Bob Carr, the project's principal investigator, who helped discover the Miami Circle. "Who lived here? How big was the settlement? What happened to terminate it? It's a puzzle."
Scientists also found evidence that the site was occupied by native peoples as early as 925.
Carr and other archaeologists drew their conclusions from artifacts found in recent weeks as workers renovated the 108-foot lighthouse, a landmark built in 1860.
The lighthouse now is surrounded by scrub vegetation, live oak and 11 homes occupied by Coast Guard personnel.
Researchers discovered a fragment of a tobacco pipe bowl as workers dug a new irrigation ditch in the shadow of the lighthouse. It is made from a black, lead-glazed material called Jackfield Ware, produced only in England, generally between 1745 and 1790, according to Jim Pepe, the archaeological project's field director.
In addition, experts found a piece of tabby, a plaster used as building material by the English, and sometimes the Spanish, during the colonial period.
The only other English artifacts found in South Florida were discovered in Miami about five years ago and were dated to between 1790 and 1810.
Taken together, the evidence suggests that this is the site of the long-rumored but never-found Grenville Plantation, Carr and Pepe said.
Mentioned sparingly in English historical documents, the plantation supposedly existed near the coast in what is now Jupiter during the brief British colonial period.
England gained possession of Florida from Spain in 1763 but returned it to Spain through a treaty in 1783.
A map drawn at some point during that 20-year period refers to the area as "Jupiter, now Grenville." Another map calls the inlet "Grenville Inlet."
A complete excavation is impossible because of the structures on the site, but Carr and Pepe hope to resume their work along the edges in a few weeks, believing they may find more English artifacts, including structures. But first they need Coast Guard approval to dig on federal land and about $20,000 funding.
Radiocarbon tests of oyster shell refuse, shards of ceramic bowls and other remains determined that the site was occupied more than 1,000 years ago by native Americans, the precise duration yet to be determined.
Deep excavations also established that the 40-foot, sandy hill that supports the lighthouse was formed naturally. Many residents have believed that it was a native burial site, but the archaeologists ruled that out.
_ Information from the Associated Press was used in this report.