America’s Mound Builders: The Mystery Deepens

The Oldest Known Mounds Are Now Dated to Over 6000-Years, but Under Water Could Be Even Older Ones

The term Mound Builder typically elicits images of well-known earthen mounds found all over America. These in­clude the huge 100-foot tall Monks Mound at Cahokia, Illinois, the complex of platform mounds at Moundville, Ala­bama, a spectacular effigy mound such as Ohio’s Serpent Mound or any of the thousands of other mounds still exist­ing all over the country.

Until 1997, the oldest American mound, defined as a manmade formation of earth or stone constructed with a de­liberate intent, was at Poverty Point, Louisiana. The massive Poverty Point complex was then dated to about 1500 B.C. The 1997 discovery and carbon dating of the site of Watson Brake, located about 50 miles from Poverty Point, pushed the date of the “oldest” mound to about 3400 B.C. But in 2003, excavations and new carbon dating at Poverty Point have shown that one of the small mounds at the site was constructed around 4000 B.C. Now, however, the earliest dates of America’s mounds are being pushed back even further.

In a remarkable series of discoveries, most of which have occurred in the past 4 to 5 years, two other mound builder cultures have been revealed. The term applied to the oldest of these cultural sites, shell rings, is so simple that it belies their immensity and importance. The shell rings are all found along coastal areas, and in the past few years archaeologists with the National Park Service have conducted extensive investigations of them. Another mound-builder culture, found more inland, is probably related to the shell rings and it is characterized by similar mounds erected in conjunction with extensive canal systems.

Shell Rings

Shell rings can be simple, donut-shaped embankments or highly complex geometric formations. They have long been known. However, archaeologists had simply assumed these were “fish traps” employed by recent tribes. Now it is known that the shell rings were not fish traps and they are far older than anyone imagined.

There are 51 known shell rings with most of them in South Carolina and Georgia with the remaining rings in Florida and Mississippi. Over 100 carbon dates have been obtained from them showing most were constructed between 3500 B.C. to around 1000 B.C. The oldest carbon dates come from several mounds at the Horrs Island site in Florida, which could be as old as 4380 B.C.

The rings are made from highly compacted shell mixed with ceramic pieces, bone, and other debris from human occupation. Literally tens of thousands of pottery shards have been excavated from the shell rings in the limited re­search that has been done. The formations are geometric embankments deliberately shaped into either a U-shape or an elevated circular ring, often with several rings joined together. The height of some of the embankments exceeds 20 feet. A flat plaza area is located within the formations where archaeologists now believe ceremonies were held. The diameter of the circular and C-shaped rings found in Georgia average 175 feet while in South Carolina the diameter averages 211 feet. Florida’s shell rings are usually U-shaped and average 587 feet in length. The largest is the Joseph Reed shell ring in Florida, which is 825 feet long. This immense formation was constructed in 1550 B.C.

A special 2002 paper on the rings was issued by the National Park Service as an effort to move the rings to Nation­al Historic Site status as a means of protecting them. The paper related, “Shell rings were the first, large-scale archi­tectural features constructed along the United States coasts and among the first in the entire United States. At a number of shell-ring sites, however, other architectural features were collaterally constructed. These include cause­ways, ramps, walls, ridges, and ceremonial mounds.”

The implications of the findings at shell rings are unexpected. Over 6000 years ago massive societal building pro­jects were made that involved large numbers of people in organized labor. The current scenario that mainstream ar­chaeologists have put together is that the people who made the shell rings were bands of archaic hunter-gatherers who gradually migrated to coastal areas. As they learned to fish and make pottery, they erected ceremonial sites as part of periodic feasting and other religious activities. The shell mounds were, according to this scenario, deliberately formed into the unusual shapes for an unknown cultural purpose. As sea levels rose to their current levels, the loca­tions of the shell mounds were so close to coastal areas that it made their ongoing use untenable. These people then moved further inland and developed even more sophisticated mound sites. These sites are described in the next sec­tion; however, archaeologists from the National Park Service cite a curious fact in their reports. The American shell rings are similar to shell rings found at Shavante tribal sites in Brazil. Thus, the origin and subsequent migration of the people who built the enigmatic shell rings in America is speculative.

Mounds, Geometric Earthworks, & Canals Appear in Florida

Modern Florida has—literally—at least a thousand mounds still in existence. Most of these are small burial mounds or midden mounds; however, in recent years archaeologists have altered their beliefs about some of the most impressive but least-known sites. We’ll describe a few.

To the north of the Everglades and around Lake Okeechobee are several massive mound complexes. The mounds are made from shell, sand, earth, ceramic shards, and midden material. One of these is Ortona Indian Mounds located north of La Belle, FL. Ortona is a curious assortment of 17 mounds and distinctive, geometric earthworks. The site is dated to as early as 1000 B.C., about the time the shell rings were being abandoned. The Ortona complex is actually scattered over five square miles, but it focuses on a central set of mounds on the north side of the Caloosahatchee River. When the site was first surveyed in 1839, an extensive canal system was found, which led the surveyors to be­lieve that Europeans probably constructed the site. However, in 2002, archaeologists announced that the canals were built by the same natives who erected the mounds and reported that the canals were formed around A.D. 300. Por­tions of the canal system remain at the site and ground-penetrating radar has been performed to identify other sec­tions. The identity of the tribe that built the site remains unclear but is popularly attributed to the Calusa. The canals are 25 feet wide, 6 feet deep, and 4 miles long, and were built for canoes to bypass falls on the nearby river. They al­low water passage from this south Florida site all the way to the Gulf of Mexico.

Not too far from Ortona in Indiantown, FL is the Big Mound City site. At least 17 platform mounds once stood in this massive mound complex, which is now adjacent to and partially included in a county park. Complex circular and linear earthworks radiate from most of the mounds to a central horseshoe-shaped earthwork.

Another mound complex with an extensive system of canals is on Big Mound Key Island located to the southeast of Placida, FL. A massive 15-acre, 23-foot-high shell mound is found in this 4000-acre archaeological district. Several curving elevated earthworks, projecting off the central ovoid mound like fingers or arms, lead from the central mound running from 320 to 500 feet in length. A few archaeologists speculate that the mound may actually be an ef­figy mound of an octopus. Based on reconstructions of the site, the octopus effigy is difficult to imagine.

Located near the Florida Everglades is Big Tony’s Mound site. The earthworks at Big Tony’s are linear and circular with some of the embankments radiating from a central plaza area. There were at least 14 mounds once located here, all of which were rounded platform mounds, each of which included a structure on the flat top. The mounds are all connected to the earthworks either at the terminal end of a linear earthwork or incorporated into a curving earth­work. The site dates to 450 B.C. to A.D. 200. Nearby is the Fort Center earthwork complex, which probably dates to the same time period and culture. Fort Center is a complex of 12 mounds and earthworks. Because the site has circular embankments, linear embankments, and earthworks with attached mounds, some archaeologists have suggested it is a Hopewell culture site. That too is speculative.

In northeast Florida at the St. John’s River is the Shields Mound. It is a huge platform mound with two levels situ­ated atop a bluff. The northernmost portion of the platform mound is oval and lower than the elevated, huge rectan­gular platform to which it is attached on the south. An elevated earthwork runs to the south for nearly a mile, termi­nating into what was possibly a circular reservoir area. The platform mound has a base diameter of about 214 feet and a height of 18 feet.

Finally, another curious complex was located at Tierra Ceia, located south of St. Petersburg. Tierra Ceia was once a massive, 10-acre complex of 2 large, flat midden and shell mounds with elevated earthwork walkways. Two other oval-shaped platform mounds with a temple structure on the top were at the site. The huge, flat midden mounds were used as habitation platforms that were elevated above the nearby water.

These are not the only such sites in Florida, but they represent a curious and unexplained transition in America’s mound builder culture. Traditionally, the mound-building era is referred to as the Woodland Era. Poverty Point, Ade­na, Hopewell, and Mississippian cultures supposedly emerged sequentially in an overlapping time period and are the primary cultural terms used to describe the main phases of the Woodland period. But clearly, the traditional archaeo­logical view has missed something. In short, the origin of the mound builder culture isn’t as simple as we have been led to believe.

Where Are The Oldest Mounds?

A frequent question asked about America’s mounds is, where is the oldest mound? It is actually an important question, because it has direct relevance to the origin of the mound culture, assuming there actually is an origin as we typically think of it. As this article related at the beginning, it is a question that has a changing answer. Right now, the oldest known American mound is the Horrs Island Shell Ring in Florida—if the 4380 B.C. date is supported by ad­ditional findings. If not, then a small mound at Poverty Point, now dated to 4000 B.C. is the oldest known. Just a few years ago it was at Watson Brake, dated to 3400 B.C. However, it is now quite clear that none of these are really the oldest mounds. We just haven’t yet found the “oldest” mound—because it is under water.

During the present author’s recent work on an encyclopedia of America’s mounds, a long discussion was held with one of America’s foremost underwater archaeologists. The discussion involved shell rings and recent finds of ar­chaeological sites off Brazil’s coast, the Chesapeake Bay, and the southeast coast. Simply stated, the oldest mounds are most likely to be found along submerged coastal areas around Florida, Georgia, and perhaps the Gulf of Mexico states. These mounds will probably be similar to the shell rings that have only recently been identified and described at the beginning of this article. They were constructed at times of lower sea levels. As the water rose, the sites were abandoned and the inhabitants moved further inland. More mounds were built, and as the waters rose, they moved still further inland. And the chances are that these underwater mounds will extend back many thousands of years ear­lier than what we today recognize as the “oldest mound.” Despite its high profile in the media, little effort is being de­voted to underwater archaeology on America’s coasts. Funding limitations are the main reason why this is so, but ad­ditionally, it should be said that relatively little is known about many ancient sites on land—and these are much more easily accessible. However, in coming years what we think we know about the mound builders—and where they started—will go through a drastic revision.


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