CHILLICOTHE, OHIO—National Park Service archaeologists excavating in an area known as the Great Circle at Hopewell Culture National Historical Park have found stains of darker soil that they think could be evidence of a woodhenge, or circular enclosure of wooden posts, built between 1,600 and 2,000 years ago. “I am very confident that those represent wooden posts,” team leader Bret Ruby told The Columbus Dispatch. The Great Circle measures 375 feet in diameter and was identified by magnetic testing several years ago. The excavation has also uncovered a six-inch-long stone tool that may have been used for cutting wood or digging.