Located on the grounds of Louisiana State University (LSU) in Baton Rouge, the LSU Campus Mounds (16EBR6) are two Native American earthworks standing at the very edge of a twenty-foot-high loess bluff overlooking the Mississippi River and its vast floodplains. The mounds have long been campus landmarks, but many people do not realize their significance as one of the oldest mound groups in the United States. Indeed, in light of their early construction dates, their excellent state of preservation, and their research potential into lifeways of the distant past, the LSU Campus Mounds were placed on the National Register of Historic Places in 1999.

Early Site Analysis

The LSU Campus Mounds site consists of two conical mounds, Mound A to the north and Mound B to the south. They range in height from 17.5 feet (Mound A) to 17.2 feet (Mound B) and in basal diameter from 130.7 feet and 120.5 feet. The larger footprint of Mound A renders it 40 percent larger by volume than Mound B.

As Robert W. Neuman notes in Introduction to Louisiana Archaeology, the first reference to the LSU Campus Mounds comes from an anonymous 1851 article in De Bow’s Review, which briefly noted the presence of American Indian mounds on the McHatton Plantation south of Baton Rouge. The property became part of the LSU campus when the university moved to its present location in the 1920s.

Despite their prominence on campus, the mounds were not explored by professional archaeologists until 1982. Three soil cores were extracted from the summits of Mounds A and B by Neuman, curator of anthropology at LSU’s Museum of Natural Science. Neuman was working with soil scientists to learn more about the age of the mounds and the pace of mound construction. To answer the question of age, Neuman radiocarbon-dated a sample of sediments from Mound A (no similar carbon-rich sediments were in Mound B). The samples were taken from the base of the mound and the underlying original ground surface in each core.  The dates (without modern correction and calibration) suggested the mounds were approximately five thousand years old. While Neuman cautiously accepted the dates (they did have quite large statistical ranges of error, plus or minus two hundred years), many archaeologists rejected them as simply “too early.” At the time, the earliest mounds in the lower Mississippi River valley were thought to date to the Marksville period (1 CE–400 CE), about two thousand years ago.

In terms of the pace of construction, the 1982 cores indicated that Native Americans built these mounds continuously over time. In general, if the construction of a mound ceases and the surface is exposed for a lengthy period of time (i.e., if a mound was built in stages), there will be changes in soil texture and chemistry indicating exposure to the elements. Such changes were not observed by the soil scientists who studied the cores at the LSU Campus Mounds.

Additional Testing

Additional testing occurred in 1985 after an LSU student was struck and killed by a vehicle driving on Mound A. Small unit excavations, shovel tests, and auger borings were placed in areas that would be disturbed by the construction of retaining walls and other landscaping designed to prevent such accidents in the future. Very few pre-European-contact artifacts were recovered in the testing. Usually sites, especially ceremonial sites, contain artifacts, like stone points or pottery, that have distinctive styles indicating when they were made. The recovery of just a few Marksville culture sherds would have been enough to reject the idea that the mounds were five thousand years old. Their absence lent some credence to the idea of the great antiquity of the mounds.

No additional work was conducted on the mounds until 2009, when LSU archaeologists and geoarchaeologists conducted remote-sensing surveys on the mounds and extracted one additional core from each mound to study their age and construction using new techniques. This Mound A core yielded another carbon-rich sediment sample to radiocarbon date, this time from 5.2 feet below the summit. Analyzed the way the samples were in 1982, the radiocarbon date was 5160 BCE, plus or minus forty years. Using recent calibrations, the sample dated to around six thousand years ago (6208–5996 2cal BP; BCE date). Applying modern calibrations to Neuman’s dates from the base of the mound produces similar results, reinforcing the idea of continuous construction.

Taken together these radiocarbon dates suggest that the mounds were built during the Middle Archaic period (6000–2000 BCE). Thus the LSU Campus Mounds were one of the first Middle Archaic mound sites to be recognized by archaeologists. Now thirteen sites in Louisiana are widely accepted to date this early.

Dating Debates

In 2022 Brooks Ellwood and other scientists (mostly from LSU’s Department of Geology and Geophysics) published the results of thirty-one radiocarbon samples from the 2009 cores of both Mound A and B. They argue the dates place the beginning construction of Mound B to eleven thousand years ago (9000 BCE)—just after the end of the Pleistocene Ice Age (11,700 years ago)—with Mound A construction starting about two thousand years later. The Mound B date puts its construction at least three thousand years earlier than previously believed and would make it the earliest human-made structure in the Americas. In addition, and contrary to the soil scientists’ interpretation of the eleven cores previously withdrawn from the mounds, the geologists interpret the 2009 cores to indicate hiatuses in the construction of both mounds between 8,200 and 7,500 years ago. Construction at both mounds resumed 7,500 years ago and continued until approximately six thousand years ago. Ironically, in this scenario, construction ended at the mounds at about the same date previously considered to be the beginning of construction.

Some archaeologists have challenged the early dates (and other issues) in Ellwood’s article. Louisiana state archaeologist Chip McGimsey and colleagues (including the authors of this encyclopedia entry) argue that the phytoliths (microscopic silicate structures inside plants that contain carbon) and organics in the sediment, which produced the very early dates, occur naturally as inclusions in the sediments and do not reflect the date the sediments were scooped up by the basketload and placed into the mounds. The authors of the rebuttal do not say the dates are simply “too early” but that Neuman’s six-thousand-year-old sediment dates from the base of Mound A, while not ideal, provide good reasons to question the Ellwood dates. The rebuttal authors suggest a different dating technique be used, one that does not rely on natural sediment inclusions. Optically stimulated luminescence, for instance, measures the time since sediment grains were last exposed to light (or extreme heat)—that is, when the sediment was buried in the mound.

This debate is simply the way normal science proceeds. Additional data is needed to resolve the issues. It took at least a decade for Neuman’s dates from Mound A to be widely accepted. It may take another decade to accept or reject these very early dates.

Native Use of the Mounds

Regardless of their exact age, the LSU Campus Mounds were probably built by Native American peoples who lived in mobile fishing, hunting, and gathering bands (of between thirty and one hundred people), with fish providing most of the animal protein. There is evidence for large base camps (like the Conly site in Bienville Parish) where people may have lived much of the year but would leave periodically to take advantage of seasonal abundances of resources elsewhere. In the past they assumed that people who lived this way were egalitarian; that is, there were no social hierarchies except for distinctions by age and sex. Such anthropologists also held that egalitarian bands did not have a level of social organization capable of constructing monumental architecture such as earthen mounds. These models of human society generally assume that such projects require full-time leaders capable of mobilizing, controlling, and directing that labor; anthropologists used to say that “mounds equal chiefs.” Today most archaeologists agree that egalitarian Archaic peoples were indeed capable of building monumental community structures such as the LSU Campus Mounds. The organization and direction of such projects could be undertaken by communally appointed temporary leaders or ad hoc groups consisting of one or more related families. Coercive tactics were likely unnecessary because the mounds held social significance for all members of society, not just a select few. The LSU Campus Mounds seem to have been expressions of group identity.

There is no evidence that the mounds served as platforms for elite structures as they did for more recent cultures. A general lack of artifacts in and around the mounds further indicates that the site was not a village where people lived. Current thinking holds that the LSU Campus Mounds served as a ceremonial center where different bands who lived scattered across the landscape came together (perhaps on a seasonal basis) for rituals, to exchange information, to dance and feast, and to find partners from other kin groups.

Current Conditions and Plans

Due to their age, tree damage, erosion, and modern wear and tear, the mounds have become unstable. Slump scars and earth slides are visible on both mounds. To minimize future disturbance at the mounds and stabilize current deterioration, LSU is working to implement a new design concept seeks to keep people off the mounds and increase the buffer around them for further protection. The plan includes plantings and additional landscaping to discourage wandering off the adjacent pathways as well as non-intrusive fencing and an observation deck to allow unencumbered views of the site. The mounds themselves will be stabilized in consultation with engineers, and a new ground cover will be planted. This cover minimizes the need for mowing and other potentially damaging maintenance. The long-term concept envisions rerouting nearby roads to lower traffic vibrations.