9 July 2025 The Future is the Product of the Past

11,000-Year-Old LSU Campus Mounds Are Oldest Known Human-Made Structures In North America

According to new research published in the American Journal of Science, two six-meter (20-foot) high mounds on the campus of Louisiana State University (LSU) are the oldest human-made structures ever discovered in North America.

Using radiocarbon dating, the researchers determined that the construction of the mounds began around 11,000 years ago and was completed over several millennia.

The two large, grassy mounds on LSU’s campus, are among the more than 800 human-made, hill-like mounds in Louisiana, built by ancient indigenous people. While many mounds in the region have been destroyed, the LSU Campus Mounds have been preserved and are listed on the National Register for Historic Places.

“There’s nothing known that is man-made and this old still in existence today in North America, except the mounds,” said LSU Department of Geology & Geophysics Professor Emeritus Brooks Ellwood.

Ellwood and colleagues collected sediment cores from the two LSU Campus Mounds to learn more about them. Layers of ash from burned reed and cane plants, as well as burned osteons, were discovered in the cores. Radiocarbon dating of the layers of material indicates the mounds were built over thousands of years.

The LSU Campus Mounds pictured here are the oldest known man-made structures in North America. Photo: LSU

These findings indicate that the first mound was constructed around 11,000 years ago. Because of a large depression in the ground behind LSU’s Hill Memorial Library, the scientists believe the sediment for the southern mound, dubbed “Mound B,” was taken from there. The mound was built up layer by layer over a few thousand years to about half its current height.

“The layers of reed and cane phytoliths, containing very small numbers of osteons, are indicative of very hot fires,” write the authors. Such infernos would have been too hot for cooking, and are therefore likely to have served a ritual function. “This finding supports the argument that the fires were used for ceremonials or cremations,” continue the researchers.

Tantalizingly, the team was unable to determine whether the osteons were of a human or animal origin. The team said they sought permission to perform DNA tests on the microscopic bone materials found, but were not granted permission by the Native American tribal communities contacted.

Around 8,200 years ago, the southern Mound B was abandoned. Tree roots found in the 8,200-year-old sediment layer indicate that the mound was not used for about 1,000 years. Also around 8,200 years ago, the northern hemisphere experienced a major climate event with temperatures suddenly dropping on average by about 35 degrees Fahrenheit, which lasted about 160 years.

LSU Department of Geology & Geophysics Professor Emeritus Brooks Ellwood led the study that has revealed new information on the LSU Campus Mounds including the discovery of thousands of years old charred mammal bone fragments and a coordinated alignment of both mounds toward one of the brightest stars in the night sky. Photo: Eddy Perez, LSU.

“We don’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 daily life,” Ellwood said.

Then, around 7,500 years ago, the indigenous people began to build a new mound just to the north of the first mound. However, this time, they took mud from the floodplain where the entrance to LSU’s Tiger Stadium is currently located, which at that time was an estuary. With this mud, they built the second mound, “Mound A,” layer by layer, to about half of its current height. Mound A contains mud that is saturated with water, which liquefies when agitated. As a result, Mound A is unstable and degrading, which is why it is critical to stay off the mounds to preserve them.

According to the new analyses of the sediment layers and their ages, it looks like indigenous people cleared the abandoned first-built Mound B and began to build it up to its current height before completing Mound A. Both mounds were completed around 6,000 years ago and are similar in height.

According to the researchers, the structures are aligned with a point on the horizon that is 8.5 degrees east of true north. Six millennia ago, the red giant star Arcturus – which is among the brightest stars in the sky – would have risen at this very point.

Study author Brooks Ellwood, “the people who constructed the mounds, at about 6,000 years ago, coordinated the structures’ orientation to align with Arcturus, seen in the night sky at that time,” said.

The two small hills have withstood the test of time, leading the authors to speculate that “the LSU Campus Mounds may represent the oldest known and still intact, human-made structures on Earth.”

The study was published in American Journal of Science

Louisiana State University

Cover Photo: LSU

Related Articles

7,000-Year-Old Alutiiq Villages Discovered on Alaska’s Shuyak Island

3 July 2025

3 July 2025

A recent archaeological survey led by the Alutiiq Museum has revealed significant discoveries on Shuyak Island, part of the Kodiak...

1,500-year-old feast mosaic found in Turkey

2 February 2022

2 February 2022

A 50-square-meter mosaic depicting an open-air feast dating back 1,500 years ago was unearthed during excavations in the ancient city...

Archaeologists uncover intact 16th-century quayside in the Belgium town of Leper

24 March 2022

24 March 2022

Excavations at Leper (Ypres), located in the West Flanders province of Belgium, have uncovered a 16th-century quayside. The find was...

A submerged stone bridge constructed 5600 years ago shed light on the human colonization of the western Mediterranean

31 August 2024

31 August 2024

An interdisciplinary research team, led by University of South Florida (USF) geology Professor Bogdan Onac, has examined an ancient submerged...

During roadwork in Oregon, a woolly mammoth tusk was discovered

21 June 2021

21 June 2021

A 12,000-year-old woolly mammoth tusk was discovered beneath the street by crews rerouting a gas line in Corvallis, Oregon. “Whenever...

4,500-year-old rare Canaanite goddess sculpture found by a farmer in Gaza Strip

25 April 2022

25 April 2022

A farmer in the city of Khan Yunis, in the southern Gaza Strip, found a rare 4,500-year-old stone sculpture while...

Export barred on roundel manuscript gifted to Queen Elizabeth I by Archbishop

12 September 2022

12 September 2022

A rare presentation manuscript that Archbishop of Canterbury Matthew Parker gave to Queen Elizabeth I in 1573 has been sold...

Iron Age Children’s a Unique Funerary Building Discovered in Oman

3 March 2024

3 March 2024

Archaeologists have uncovered a unique Iron Age children’s funerary building at the Manaqi archaeological site in Rustaq, South Al Batinah...

Researcher Says There is Similarity Between Mayan and Shu Cultures

12 April 2021

12 April 2021

The similarities between Mayan civilization and Shu culture draw the attention of researchers. As it is known, the Sanxingdui ruins,...

An Egyptian Tomb Decorated with Magic Snake Spells Discovered

9 November 2023

9 November 2023

During excavations at Abusir, between Giza and Saqqara, archaeologists at the Czech Institute of Egyptology (CIE) found an ancient tomb...

An inscription written in both runic and Latin script on a church wall in Denmark turned out to be still a legally significant promissory note

31 May 2023

31 May 2023

An inscription in both runic and Latin script on a church wall in Denmark turned out to be legally valid...

Archaeologists discover complete armored 14th-century gauntlet in Switzerland

18 January 2024

18 January 2024

Excavations in Kyburg in the canton of Zürich, northeastern Switzerland have discovered a 14th-century fully preserved gauntlet of armor in...

Norse Runic Text found in Oslo could be Prayer!

30 December 2021

30 December 2021

Archaeologists from the Norwegian Institute for Cultural Heritage Studies (NIKU) have unearthed two objects inscribed in Norse runic text in...

Exceptional Intact Etruscan Rock-Cut Tomb Discovered in Italy’s San Giuliano Necropolis

30 June 2025

30 June 2025

A remarkable discovery has emerged from the heart of Etruria: an intact Etruscan rock-cut tomb, sealed for over 2,700 years,...

“Secret” Excavations in Luxembourg Reveal 141 Roman Gold Coins from Nine Roman Emperors

13 January 2025

13 January 2025

Archaeologists uncovered a Roman gold coin hoard of 141 Roman gold coins dating to the second half of the 4th...