(ORDO NEWS) — There are over 800 pyramid mounds in North America. New research has shown that some of these mounds are among the most ancient man-made structures on the continent.
In addition, the top of each mound is located along an azimuth that is about 8.5 degrees east of true north. The first mounds were built about 11,000 years ago. Interestingly, the mounds are aligned with the star Arcturus.
The researchers found charred fragments of mammalian bones and the alignment of both mounds towards one of the brightest stars in the night sky.
As a result of this new information, we have received more information about the most ancient man-made structures in the Americas.
More than 800 man-made, pyramid-like mounds have been discovered in Louisiana, two of which are on campus. While many of the mounds in the region have been destroyed, the mounds on the LSU campus have been preserved and listed on the National Register of Historic Places.
This study was published in the American Journal of Science by Yale University.
To better understand the condition of two mounds on the LSU campus along Dalrymple Drive, Ellwood and colleagues collected sediment cores. In the cores, reeds and reed plants burned by fire, as well as bones of mammals, were found.
According to radiocarbon dating, the layers of material indicate that the mounds were built over thousands of years. There is evidence that the first burial mounds were built about 11,000 years ago.
There is a large depression in the ground behind the Hill Memorial Library at LSU, so scientists believe that the sedimentary material for the southern mound, called Mound B, was taken from there. Approximately half of the current height of the mound was built over several thousand years.
Ashes and microbes charred on microscopic bone fragments indicate that the mound was used for ceremonial fires, on which reeds and reeds were burned.
There is no information about the type of mammals that were cremated or about the reasons why animals were cremated. In the ash layers of both mounds of the LSU Campus, microscopic charred bones, called osteons, were found that make up the bones of large mammals.
In the end, the southern mound B was abandoned about 8,200 years ago. A layer of sediment found in the mound dating back 8,200 years contains tree roots, which indicate that the site has not been used for about 1,000 years.
About 8,200 years ago, a major climatic event occurred in the northern hemisphere when temperatures dropped by an average of 35 degrees Fahrenheit over 160 years.
Ellwood said the environment they lived in changed suddenly and dramatically around 8,200 years ago, affecting many aspects of their daily lives.
Then, about 7,500 years ago, the indigenous people began to build a new mound to the north of the first. In this case, silt was taken from the river floodplain, where the entrance to the Tiger Stadium is now located, which at that time was an estuary.
Layer by layer they built Mound A, the second mound, to about half its current height. It contains water-saturated mud that liquefies when agitated.
In light of new studies of the sediment layers and their age, it appears that the indigenous people cleared the abandoned First Mound B before the completion of Mound A, and then began to raise it to its current height.
A similar height was reached by both mounds about 6,000 years ago, when both are believed to have been completed.
The crest of each barrow is aligned to an azimuth that is about 8.5 degrees east of true north.
According to astronomer Geoffrey Clayton, about 6,000 years ago, the red giant star Arcturus rose in the night sky about 8.5 degrees east of north, coinciding with the crests of both mounds of the LSU Campus. Arcturus is one of the brightest stars visible from Earth.
Ellwood said the mound builders matched the orientation of the mounds to Arcturus, which was visible in the night sky at the time.
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