Two six - meter ( 20 - foot ) high agglomerate on the campus of Louisiana State University ( LSU ) are the oldest homo - made structures ever discovered inNorth America , according to new enquiry in theAmerican Journal of Science . Using radiocarbon geological dating , the study source determined that building of the mounds begin around 11,000 years and was completed over several millennia .
Analysis of deposit cores taken from the twoLSU Campus Moundsrevealed that they were built up in layer , the old of which check ash from burned reed and cane plants . Amongst this ash , the researcher found microscopic fragment of charred mammal bones called osteons .
“ The layers of reed and cane phytoliths , containing very modest numbers of osteons , are indicative of very hot fervour , ” write the author . Such hellhole would have been too hot for cooking , and are therefore likely to have served a ritual occasion . “ This determination confirm the logical argument that the fires were used for ceremonials or cremation , ” continue the investigator .
Tantalizingly , the squad was ineffective to determine whether the osteons were of a human or animal origin . “ We did request permission to perform DNA tests on the microscopical ivory material found , but permission was deny by the Native American tribal communities that were reach , ” they reveal .
have a go at it as Mound A and Mound B , the two knoll were assemble by ancient Indigenous cultures and were not completed until about 6,000 twelvemonth ago .
According to the researchers , the structures are aligned with a point on the horizon that is 8.5 degrees east of unfeigned north . Six millennia ago , the crimson giant star Arcturus – which is among the shiny stars in the sky – would have risen at this very point .
Commenting on this determination in astatement , work author Brooks Ellwood explain that “ the people who constructed the cumulation , at about 6,000 years ago , coordinated the anatomical structure ’ orientation to array with Arcturus , seen in the night sky at that time . ”
Through their analysis , the researchers reconstruct the history of the two cumulus , bring out that Mound B was initiated around 11,000 ago while Mound A was started some 9,500 years ago . However , the dispersion of tree diagram theme within the hillock suggests that they were abandoned for about a millenary , begin 8,200 years ago when the northern hemisphere experienced an disconnected and drastic cliff in temperatures .
“ We do n’t know why they abandoned the mounds around 8,200 years ago , but we do know their environment changed suddenly and dramatically , which may have affected many aspects of their casual spirit , ” suppose Ellwood .
Construction eventually restarted just about 7,500 twelvemonth ago , when the two mound were about half of their current height . Over the next 1,500 years , the two mounds were construct up to their present sizing , at which power point “ the LSU Campus Mounds were desolate by the Indigenous people for good . ”
Despite being desolate , though , the two small hills have hold up the test of sentence , leading the authors to speculate that “ the LSU Campus Mounds may stage theoldest known and still inviolate , man - made structures on Earth . ”
