5 October 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.



📣 Our WhatsApp channel is now LIVE! Stay up-to-date with the latest news and updates, just click here to follow us on WhatsApp and never miss a thing!!



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

A Little-Known Civilization in the Americas Built Pyramids as Old as Ancient Egypt

26 June 2022

26 June 2022

Considered the cradle of civilization in the Americas, the Sacred City of Caral-Supe is a 5000-year-old archaeological site, situated on...

Philippines Cagayan Cave Art 3500 Years Old

29 June 2021

29 June 2021

A depiction depicting a human-like figure on a cave wall in Penablanca town, Cagayan province, is Southeast Asia’s first directly...

A new study reveals more than one person was buried in a tomb where the famous Nestor’s Cup was found

6 October 2021

6 October 2021

The Tomb of Nestor’s Cup, a burial that contained one of the oldest known Greek inscriptions, was more crowded than...

4,000-year-old cylinder seal found in Blaundos excavations

29 September 2022

29 September 2022

A 4,000-year-old cylinder seal was found during the excavations of the ancient city of Blaundus (or Blaundos, as it is...

Scientists may have discovered pieces of the Asteroid that caused the extinction of the Dinosaurs

14 May 2022

14 May 2022

Scientists are piecing together remnants of the day the extinction of the dinosaurs began. A tiny fragment of the asteroid...

Archaeologists Uncover Monumental 2,800-Year-Old Lydian Palace in Sardis, Birthplace of Money

15 August 2025

15 August 2025

Archaeologists excavating the UNESCO World Heritage site of Sardis, located in the Salihli district of Manisa, Türkiye, have uncovered the...

Archaeologists in eastern Newfoundland unearth the oldest English coin ever found in Canada

14 November 2021

14 November 2021

Archaeologists in eastern Newfoundland have unearthed a rare two-penny piece minted between 1493 and 1499 more than 520 years ago....

Researchers may have found the wreck of British explorer James Cook’s Endeavour

3 February 2022

3 February 2022

The wreck of Captain James Cook’s famed vessel the Endeavour has been found off the coast of the U.S. state...

Hunting tools Dating Back 1900 Years Found inside a Cave in Querétaro, Mexico

27 January 2024

27 January 2024

Archaeologists from the National Institute of Anthropology and History (INAH) found hunting weapons dating back approximately 1,900 years in a...

New Study Finds, 4,000-Year-Old Toolkit Unearthed Near Stonehenge Was Used to Work Gold

16 December 2022

16 December 2022

Archaeologists from the Universities of Leicester and Southampton in the United Kingdom recently published a study claiming that enigmatic artifacts...

Archaeologists Uncover Evidence of British Rule in Florida

29 March 2025

29 March 2025

A recent archaeological excavation in St. Augustine, Florida, has revealed a British redoubt dating back to 1781, offering valuable insight...

Whispers of Time: Exploring the Enigmatic Bronze Age Towers of Oman

24 February 2025

24 February 2025

The ancient Bronze Age towers scattered across Oman, dating back nearly 5,000 years, have long been a subject of curiosity...

Game Bone Stones from a Roman Military Strategy Game Found in Hadrianopolis Ancient City, Türkiye

10 January 2025

10 January 2025

During the excavations in Hadrianopolis Ancient City in Eskipazar district of Karabük, 2 bone game stones belonging to the military...

Hellenistic cremation tomb found in Istanbul’s Haydarpasa excavations

11 April 2022

11 April 2022

A brick tomb belonging to the Hellenistic period (330 BC – 30 BC) was found during the Haydarpaşa excavations, which...

1,800-Year-Old Roman Watchtower Discovered in Croatia

3 August 2025

3 August 2025

Archaeologists in Croatia have uncovered the remains of a 1,800-year-old Roman watchtower that once stood guard along the empire’s northern...