Who built the Great Serpent Mound and why? Debate on its dating
The 'Great Serpent Mound' is perhaps the most recognizable icon of ancient Native Americans. Yet, even today, its dating is a hotly debated topic among experts. Radium carbon dating appears to indicate the mound was made by the Fort culture around 1120 AD. But a recent study suggests it may be an Adena culture mound, dating it back to 1000 BC.
The Great Serpent Mound is a large prehistoric geoglyph located on the Brush Creek Crater Plateau in Adams County, Ohio. At 420 meters long, the embankment represents the largest effigy of a serpent engraved on the soil of our planet.
The figure follows the curvature of the ground on which it rests, with its head placed near a cliff near a stream and apparently with its mouth open, while it pounces on an oval figure, which according to scholars could represent an egg, the sun, the body of a frog, or simply the remnant of an ancient platform.
Although similar burial mounds exist in both Scotland and Ontario, the one in Ohio has characteristics that are still the subject of speculation. The Serpent Mound, for example, contains no human remains, so it was not built for funerary purposes.
Cherokee culture associates the mound with the legend of the Uktena, a great serpent with supernatural powers. The researchers hypothesized that perhaps ancient natives created large totem shrines equipped with earth and stone platforms. The other platforms built may have been destroyed during wars or the succession of various cultures, with the result that the Great Serpent Mound is the only survivor. But this is only speculation.
In 1987 Clark and Marjorie Hardman published a study showing that the oval area in front of the snake's head is aligned with the summer solstice. Subsequently, William F. Romain suggested a series of lunar alignments based on the curves of the serpent's body. Fletcher and Cameron have argued convincingly that the serpent spirals are aligned with the annual solstices and equinoxes.
The dating of the site and its builders
The dating of the design, the original construction and the identity of the builders of the effigy are the three great questions still debated in the fields of social sciences, ethnology, archeology and anthropology. The researchers attributed the construction of the mound to three different prehistoric indigenous cultures.
When the embankment was unearthed by Frederic Ward Putnam in the late 1800s, several artifacts were found near the site that belonged to what researchers identify as the Adena culture, an American population that lived between 1000 BC and 100 AD. For this reason, Serpent Mound has been attributed to the Adena culture from the beginning.
But Putnam near the site also found traces of a large village belonging to the more recent Fort culture, built on the ruins of a previous Adena village. Some thought that the embankment must have belonged to the Fort culture, moving the dating to a period of time between 1000 AD and 1750 AD. To confirm this hypothesis, radiocarbon tests were carried out on some coal fragments of wood found in the 1990s on the site, which confirmed the dating.
Recently, however, the dating has once again been called into question. William Romain and a team of scientists from various universities traveled to Serpent Mound to conduct research to obtain a more precise dating for the mound's construction. Radiocarbon dating performed on some traces of charcoal found in the soil core returned dates between 400 BC and 80 BC, reevaluating the hypothesis of the Adena culture.
But there are those who go decidedly further. According to some researchers, the mound could also have been designed in line with the astronomical model of the stars that make up the constellation of the Dragon, aligning itself exactly in its geographical center with the position of what in ancient times appeared as the Polar Star, Thuban (α Draconis).
Based on this measurement, taking into account the procession of the equinoxes, when Thuban occupied the position of the North Star, it would be possible to date the Great Serpent Mound to around 5 thousand years ago, definitely before the appearance of the Adena culture.
Cryptoexplosion structure
A final and very intriguing peculiarity of the Serpent Mound was the discovery in 2003 by geologists from Ohio and the University of Glasgow (Scotland), who discovered that the embankment stands on a plateau characterized by acryptoexplosion structure.
As Bevan M. French explains in the book Traces of Catastrophe (2008), the term cryptoexplosion (or cryptovolcanic structure) means an explosion of unknown cause. The term is now in disuse and considered obsolete. It was once commonly used to describe these sites where there was no geological evidence of a large explosion within the Earth's crust.
These sites are usually circular in shape with signs of rock deformation, markedly at odds with the surrounding region, often showing evidence that the rock material had been lifted or 'blown' outwards. Some unusual form of volcanism, or explosion of gases from within the Earth's crust, was thought to be the cause.
The use of the term fell into disuse with the rise of the science of impact crater recognition in the late 20th century. Most of the structures described as crypto explosions were found to be produced by impacts with celestial bodies such as meteorites and comets.
The 2003 study was carried out by studying cores taken from the Serpent Mound site in 1970. Analysis of the samples indicated that the area was affected by a meteorite impact that occurred in the Permian, approximately 286 million years ago. It is one of the few known sites in North America affected by similar phenomena.
Some scholars wonder whether the builders of the Great Serpent Mound deliberately built the embankment in this area, identifying unique features perhaps considered sacred, while others think it is a coincidence, given that no external signal could have signaled the ancient natives such an unusual geological peculiarity.
