The Great Serpent Mound is a 1,330-foot-long, three-foot-high prehistoric effigy mound located on a plateau of the Serpent Mound crater along Ohio Brush Creek in Adams County, Ohio. Maintained within a park by the Ohio Historical Society, it has been designated a National Historic Landmark by the United States Department of Interior. The Serpent Mound of Ohio was first reported from surveys by Ephraim Squire and Edwin Davis in their historic volume Ancient Monuments of the Mississippi Valley, published in 1848 by the newly founded Smithsonian Museum.
Researchers have attributed construction of the mound to three different prehistoric indigenous cultures. Based on the use of more advanced technology, including carbon dating and evidence from 1996 studies, many scholars now believe that members of the Fort Ancient culture built it about 1070 CE (plus or minus 70 years). There are still anomalies to be studied. Serpent Mound is the largest serpent effigy in the world.
In the late nineteenth-century Harvard University archaeologist Frederic Ward Putnam excavated Serpent Mound and attributed the creation of the effigy to the builders of the two nearby burial mounds, which he also excavated. We now refer to this culture as the Adena (800 BC-AD 100). A third burial mound at the park and a village site near the effigy’s tail belong to the Fort Ancient culture (AD 1000-1550).
A more recent excavation of Serpent Mound revealed wood charcoal that could be radiocarbon dated. Test results show that the charcoal dates to the Fort Ancient culture. This new evidence of the serpent’s creators links the effigy to the elliptical mound and the village rather than the conical burial mounds.
The head of the serpent is aligned to the summer solstice sunset and the coils also may point to the winter solstice sunrise and the equinox sunrise. Today, visitors may walk along a footpath surrounding the serpent and experience the mystery and power of this monumental effigy.