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The Serpent Mound

The Great Serpent Mound of Ohio, the Largest Earthen Effigy in the World


The Great Serpent Mound is a 1,300-foot (396 m) long and 3-foot (91 cm) high prehistoric effigy mound located on a plateau of a crater along Ohio Brush Creek in Adams County, Ohio, and is the largest surviving prehistoric effigy mound in the world. Resembling an uncoiling serpent, the mound is steeped in mystery and controversy. Despite over a century of research, there is no conclusive evidence about what it represents, when it was built, and what its true purpose was, though various astronomical alignments suggest it may have functioned as a type of calendar. Can we discern its significance?

The Unique Features and Historical Origins of the Serpent Mound

The Serpent Mound conforms to the curve of the land on which it rests, with its head approaching a cliff above a stream.  It winds back and forth for more than eight hundred feet and has seven distinct coils, ending in a triple-coiled tail. The serpent head has an open mouth extending around the east end of a 120-foot-long (36.57 m) hollow oval feature, which is generally viewed as an egg, although other interpretations suggest it is the sun, the body of a frog, or merely the remnant of a platform. To the west of the effigy, is a triangular mound measuring approximately 32 feet (9.75 m) at its base and long axis.  The Serpent Mound is believed to have been laid out all at once, with a layer of clay and ash, and reinforced with stones.

A digital GIS map of Ohio's Great Serpent Mound, created by Timothy A. Price and Nichole I., 2002.  (CC BY-SA 3.0)

A digital GIS map of Ohio's Great Serpent Mound, created by Timothy A. Price and Nichole I., 2002.  (CC BY-SA 3.0)

Thousands of years ago, Native American peoples populated the Ohioan landscape with mounds and massive earthworks. Initial research attributed the effigy to the Adena culture, which flourished from 1000 BC to 100 AD.  The Adena culture are well-known for building burial and effigy mounds, many of which are located near the Great Serpent Mound.  However, radiocarbon dating on pieces of charcoal found within the Serpent Mound established that people worked on the mound around 1070 AD.  Thus, the mound may have been built by the Fort Ancient peoples, who lived in the Ohio Valley from 1000 to 1550 AD.  Nevertheless, the testing is not conclusive as it only reveals that 1000-year-old charcoal was found within the mound. This could have ended up there long after the effigy was originally built.

Interpretations of the Serpent Mound

The most predominant theory is that the Serpent Mound represents a giant snake, which is slowly uncoiling itself and about to seize a huge egg within its extended jaws. However many theories abound suggesting various interpretations. For instance, some think it may represent an eclipse, or the phases of the moon. Others have speculated that it represents the myth of the horned serpent found in many Native American cultures. In 1909, local German Baptist minister Landon West proposed another unusual theory: the serpent was writhing in its death throes as punishment for tempting Adam and Eve in what West believed was the original Garden of Eden.

There are serious suggestions that the serpent is intimately connected with the heavens. Several writers have suggested that the serpent is a model of the constellation we call the Little Dipper, its tail coiled about the North Star.

Various alignments of the serpent correspond to astronomical features, such as alignments of the sun and moon. In 1987 Clark and Marjorie Hardman published their finding that the oval-to-head area of the serpent is aligned to the summer solstice sunset, suggesting that one of the effigy’s purposes was to mark the turning of the year so that planting and gathering and hunting could be planned.

William F. Romain has suggested an array of six lunar alignments corresponding to the curves in the effigy's body. If the Serpent Mound were designed to sight both solar and lunar arrays, it would be reflect the consolidation of astronomical knowledge into a single symbol.

View of the The Great Serpent Mound, one of the most important prehistoric effigy mound of Adena Culture, located on the Ohio River, USA.  (Timothy A. Price and Nichole I. /CC BY-SA 3.0)

View of the The Great Serpent Mound, one of the most important prehistoric effigy mound of Adena Culture, located on the Ohio River, USA.  (Timothy A. Price and Nichole I. /CC BY-SA 3.0)

Generations of researchers agree with the theory that the Serpent Mound holds astronomical significance, but the intent of those who built the serpent, and how it was used still remains a mystery. 

Many scholars believe the Serpent Mound was used in religious ceremonies. When settlers first discovered the mound, there was a fire-scorched stone monument in the egg-shaped head, which has led some to suggest it was used as an altar of some sort – possibly sacrificial, based on the ceremonial knives unearthed among the blackened stones and a number of headless skeletons discovered in gravesites nearby.

Whatever its true purpose, the Serpent Mound attests to the ingenuity of its creators. As the Ancient Ohio Trail website so aptly states: “The genius of its designers remains apparent: this blend of beauty, familiarity, abstraction, power, precision, and mystery, make Ohio’s Serpent Mound one of the great, iconic images for all of human antiquity.”

Pathway to Prestige

Standing the test of time, Serpent Mound has encountered its share of difficulties. Over many centuries, it confronted deterioration due to natural elements and human actions. Fortunately, through the unyielding efforts of archaeologists and conservationists, the mound was safeguarded and designated as a National Historic Landmark in 1964.

In 2008, the U.S. Department of the Interior included Serpent Mound, alongside other Native American earthworks in Ohio, on the United States’ tentative list of sites for submission to UNESCO (the United Nations Educational, Scientific, and Cultural Organization). This submission aims for inclusion on the esteemed list of World Heritage Sites. Should the inscription proceed, which may occur in 2023 as projected by Jennifer Aultman, the World Heritage Director at Ohio History Connection, Serpent Mound will become part of the honoured collection of World Heritage Sites.

Top image: The Serpent Mound. Source: Szecska/CC BY-NC-SA 2.0

By Joanna Gillan


Arc of Appalachia Preserve System . Serpent Mound. Available at:

Indian Country Media Network. Crazy Theories Threaten Serpent Mound, Demean Native Heritage. Available at:

Ohio Historical Society. Serpent Mound –Available at:

The Ancient Ohio Trail . Serpent Mound, the World’s Most Famous Earthen Effigy. Available at

The Metropolitan Museum of Art. 2002. Heilbrunn Timeline of Art History Great Serpent Mound. Available at:



Pete Wagner's picture

Archaeologists come up with the silliest theories.  The dubious habit probably started long ago by some self-anointed expert on Egypt or somewhere over there, then spread like a virus to all the universities, with their similar ivory tower mentality of 'thou shall NOT question my theories!'  But here and now, with the institutional house of cards, too amateurish, too sloppy, too leaning, just too utterly bad.  The institution is blind to it, they don’t see in the mirror, the face of the silliness.

But okay, let’s try to go with the silliness and imagine how it might have happened their way, ...that “the Serpent Mound represents a giant snake.” So the ancients would first have to have come up with the idea before they decided to build it, right?  Probably the chief, or one of the elders says, ‘...okay, let's all drop what we’re doing, I have a cool idea, but we need all the strongest men involved, the all the others will have to double up on the hunting, fishing and gathering to feed them, ...we’ll figure out a way to line up a big diagram over the land, make it in the form of a snake!  Yeah, snake!  Not a fish or a bird but a snake, because snakes are cool!  Then it just becomes a matter of digging and moving all that dirt and stone to create it.  But don't worry, it’ll be all worth it in the end, when we’ll have this snake on the hill, that the birds, flying way up there, might look down and also think is a cool thing.  So, let’s roll with it!’  Were they that insane?  Or is insanity just a modern thing?

But no, the winding shape of it had to have served a FUNCTIONAL purpose.  Seems to me, if you had a mound, and you wanted to use it as a winter shelter, which makes sense, to get the most interior living space or storage space out of it, without digging out too much and having it collapse on you, you would dig a curvy cavern through it.  Maybe the archaeology curriculum should have a requirement for logic and civil engineering? 

Nobody gets paid to tell the truth.

Pete Wagner's picture

Why would the stars have anything to do with it?  Where do the stars influence the design of a modern structure?

Nobody gets paid to tell the truth.

Uno Raza's picture

Here's a decode of Ohio's Serpents Mound; it's most important meaning is spiritual and actually refers to the same meaning as the famous "Samson's Riddle" found in Judges 14:14.

Here's a simple illustration:

Phil Harris's picture

New archaeostronomy evidence about Serpent mound actually being related to the constellation Hydra and not Draco,. With a ton of images and information about the mound and astronomy. Written by my friend Chris Donah for my website.

I think that it could be a representation of the meteor that crashed at that location and transformed the area. Perhaps people who witnessed the original event passed down their description of what happened. The tail would have been the streak in the sky, the head the flash of entry into the atmosphere, and the egg the meteor that struck the Earth.


Joanna Gillan's picture


Joanna Gillan is a Co-Owner, Editor and Writer of Ancient Origins. 

Joanna completed a Bachelor of Science (Psychology) degree in Australia and published research in the field of Educational Psychology. She has a rich and varied career, ranging from teaching... Read More

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