In the eastern United States, nestled among the trees beside a branch of the Ohio River, lies one of the most peculiar and mysterious earthworks ever created by humankind: the Great Serpent Mound. This serpent mound is less than 1 meter high but stretches over 400 meters and is clearly visible from above.
This special mound is primarily constructed from a layer of yellow clay.
The Great Serpent Mound is considered the largest serpent mound in the world. The earliest records of this site come from surveys conducted in the 19th century by Ephraim Squier and Edwin Davis. They wrote about this mysterious serpent mound in their historical book “Ancient Monuments of the Mississippi Valley” published in 1848.
In fact, the entire structure of the serpent mound is divided into three parts, featuring a snake-like shape that extends 419 meters and varies in width from 6 to 7.6 meters. The head of the serpent reaches towards a cliff above a stream, with its body curving back and forth.
The mound itself was primarily constructed from a layer of yellow clay and was reinforced with a layer of stone before being covered with earth. The head of the serpent appears to be attempting to engulf a circular mound approximately 37 meters long.
There has been considerable debate among scholars regarding the unique shape of this mound, whether it represents an egg, the sun, or some specific object.
The entire structure of the serpent mound is divided into three parts with a snake-like shape.
Interestingly, there are similar serpent mounds found in other parts of the world, including Scotland and Canada. With its vertical shape and low height compared to its other dimensions, this serpent mound is categorized alongside Peru’s Nazca Lines. These structures are suited for aerial observation — which seems impossible in the era when they were created.
Archaeologists have debated the origins of the serpent mound for decades. Numerous excavations have taken place, but no artifacts or burials have been found that can directly help determine when it was formed and the precise reasons for its construction.
No artifacts or burials have been found around the serpent mound area.
Currently, there are two leading hypotheses regarding who may have constructed this enormous serpent mound. Some believe it could belong to the Adena culture, which dates from 800 BC to around 100 AD.
Others believe it was built by the Fort Ancient culture, which existed from 1000 to 1750 AD. This hypothesis also suggests that the giant serpent mound was constructed around the 11th century.
With these two hypotheses, the dating of the serpent mound is inconsistent — separated by a millennium. So, why is there this uncertainty, and why are there such vastly different hypotheses?
The Adena culture is an ancient culture known to have thrived on the North American continent. William Webb, a prominent researcher, found evidence of this culture in Kentucky dating back to the early 1200s BC.
Comparing artifacts found in Kentucky with those discovered near the serpent mound, researchers believe it was constructed by the same culture, and it is known that the Adena culture extended into the Ohio Valley. At the same time, the Adena culture is also known to have built large mounds in other locations, although their shapes differ from the serpent mound.
An eight-member team led by archaeologist William Romain investigated charcoal samples from the serpent mound. Their findings date the construction of the mound to between 381 BC and 44 BC, aligning well with the peak development period of the Adena culture in this region.
Contrasting this hypothesis is the belief that the serpent mound belongs to the Fort Ancient culture. In 1996, a team led by Robert Fletcher and Terry Cameron reopened some excavations from the 19th century.
They found charcoal during the excavations, and upon testing, the dating of these charcoal samples was around 1070 AD. This suggests that the Fort Ancient culture, which inhabited the Ohio Valley at that time, constructed the serpent mound, possibly building it over smaller mounds created earlier by the Adena culture.
However, this hypothesis also has its issues. Mound construction is not characteristic of the Fort Ancient peoples. Additionally, the mound does not contain distinctive artifacts, nor are there any notable graves found near the serpent mound, which is unusual for the Fort Ancient culture.
Nonetheless, many believe that both hypotheses may be correct. Perhaps the Adena culture originally created the serpent mound, and then a thousand years later, the Fort Ancient culture repaired the damaged parts of this mound over time.
The mound may have been used to mark time or seasonal changes.
Based on research conducted in 1987, it is suggested that the circular mound and the head of the serpent align with the sunset on the summer solstice. Meanwhile, the tail of the serpent points towards the sunrise on the winter solstice.
This indicates that it may have been used to determine time or seasonal changes. This method could have advised local residents on when to plant or harvest crops.
Additionally, the curves along the body of the serpent have been identified as parallel to the phases of the Moon, alternating with the two solstices and two equinoxes.
