Underwater site opens window on big environmental change

By George Wisner

Florida researchers are opening a window on a time when Paleoindian hunter-gatherers were adjusting to a dramatic climate shift at the close of the last Ice Age. Early Floridians were poised on the knife-edge of transition to a more sedentary lifestyle.

Evidence from an underwater site in the Aucilla River southeast of Tallahassee is presenting a unique view of the cultural dynamics of the change occurring about 10,000 years ago, according to Brinnen S. Carter, a doctoral archaeology student at the University of Florida in Gainesville. He is overseeing excavation of the site that has yielded projectile points, an apparent hearth, and what probably are bola stones. Also recovered in the excavation were wood fragments that may be tent stakes or building poles. Wooden artifacts are seldom preserved at sites of this age.

Colloquially known as the “Bolen component” of the Page-Ladson site, the late-Pleistocene strata are being investigated as part of the long-term Aucilla River Prehistory Project (“Underwater Site Details Mastodons’ Life History,” Mammoth Trumpet 10:1). Research has been in progress for more than a dozen years, and scores of Paleoindian sites and Pleistocene-mammal sites have been discovered beneath the waters of the lower Aucilla and other rivers in northwest Florida (“Florida Archaeologists Plunge into the Past,” Mammoth Trumpet 3:2).

The Bolen component is providing “the first step in being able to say what the people living then were doing in the local area, and how they adapted to the rapid environmental changes that were occurring,” Carter said in a telephone interview. There is little question that the changes were dramatic.

Before the end of the last Ice Age, the site—now under 15 feet of water—was part of a considerably drier landscape. It was about 100 miles from the Gulf of Mexico and the river was intermittently dry. From 10,000 to 5,000 years ago melting glaciers had brought the site to within about five miles of the Gulf by raising sea levels approximately 80 meters. The inhabitants 10,000 years ago must have watched as pine ecosystems initially gave way to thick oak forests. Scientists believe that the greatest degree of change in Florida’s flora occurred at precisely that time.

The change would have deprived people of familiar resources while offering them new ones. Carter believes that the people were well enough adapted to their environment before the changes that they could easily withstand them. Environmentally initiated cultural adaptations soon followed. These Paleoindians probably became less nomadic. Carter says they settled in villages, and produced new styles of stone projectile points and a variety of new hunting and gathering instruments. Later generations ultimately turned to agriculture as a survival strategy.

Researchers believe the window presented by this site, which Carter believes was a seasonal camp, allows them to clearly view a transition point for a culture.

“These people were the region’s first humans who weren’t big-game hunters,” says Carter. Mammoths and mastodons, which formerly had been hunted or scavenged, vanished, so the people came to rely on smaller animals. Faunal materials are sparse at the site, Carter said. But fish bones and burned turtle bones are evidence of one potential shift in subsistence. And they had to adapt to changing vegetation.

“My guess is they were well attuned to those resources prior to changes and were merely shifting their emphasis to the new resources. It doesn’t look to me like they really changed their essential way of interacting with the environment; they didn’t simply adopt agriculture, they remained hunter-gatherer groups.”

He estimates that people lived at the site for only a few generations, until rapidly rising water levels about 10,000 years ago forced them to move. Rising water also sealed the remains of their camp under a protective layer of clay that enhanced artifact preservation.

The density and amount of artifacts preserved in the Bolen component of the site is quite amazing, says Dr. David Webb, Curator for Vertebrate Paleontology at the Florida Museum and a principal investigator of the Aucilla River project.

The site is in the middle of a swamp on the west bank of the Aucilla River. Tannin in the swamp water allows daylight to penetrate only to a depth of seven or eight feet. At a depth of 15 feet, Carter says, the crew must work in “a Heart of Darkness” environment using powerful lights for illumination. Though stained, the water is relatively clear. Excavation is time-consuming, and field workers must be competent divers. Carter, who has a master’s degree in nautical archaeology from Texas A&M University, has been working at the site since 1988. His specialty is the late-Paleoindian period.

A buried soil surface, or paleosol, is the focal point for the excavation that so far has covered about 22 square meters. The site seems to extend farther into the river’s bank, but to follow it is not yet practical because it would require removal of up to five meters of overburden.

The underwater archaeologists have found side-notched Bolen projectile points, which have been stylistically dated to between 10,200 and 9,900 years ago. One piece of cypress wood recovered from the Bolen level yielded a date of 10,000 ± 80 radiocarbon years (Beta 21750); a piece of wood in compacted soil below the paleosol’s surface produced a date of 10,280 ± 110 radiocarbon years (Beta 21752).

Other cypress wood that may have been part of either a canoe or a large log, believed to have washed into the site after the flooding, yielded a date of 9,930 ± 60 radiocarbon years (Beta 58858). Carter says he has more samples to be radiocarbon dated—hickory nuts and seeds carefully teased from the surface of the paleosol and overlying clay layers.

In a layer dating to the Bolen period, team members recovered what they believe is a completed bola stone from another part of the site. Carter described it as teardrop-shaped, four to six centimeters in diameter, with a small dimple on top. It was part of a weapon of thong or cord thrown to ensnare wildlife. They also found what is probably a bola-stone preform that broke before it was finished, and another bola-stone fragment on the paleosol surface.

‘It looks like this could be some kind of bola-stone manufacturing site,’ Carter said. Possibly bolas were being pecked to proper shape. Alternate hypotheses to these stones being for bolas could be that they were heads for maces or clubs, or perhaps hammerstones for percussion knapping of flaked stone tools.

Another interesting feature is a hearth, depressed about eight centimeters into the surrounding surface, which contained a piece of wood charred on one side but not on the other. Carter says it presumably is the same age as other materials from the Bolen surface.

Among small wooden stakes recovered was one found driven vertically through the paleosol. Carter said that stake yielded an accelerator mass spectrometry date of 8,905 ± 65 radiocarbon years (UA-7454). “It is difficult to say this is evidence of some kind of shelter, but my inclination is that it is some kind of structure. The stake in the paleosol was about three meters from the hearth.

The team has recovered what appear to be adzes or adze preforms, but no lithic flakes. “We are not seeing any debitage, just finished flaked and ground stone tools,” Carter says. “Maybe we are seeing some new type of site that’s only found in an underwater context or adjacent to a stream.”

At the very least, he added, the site is providing researchers with a significant opportunity to gain new insights into a critical period of human adjustment to sweeping climatic changes.

The Aucilla River Prehistory Project has financial support from the National Geographic Society and a Florida Department of State Special Grant.


Editor’s note: This article is reprinted from the Center for the Study of First Americans’ newsmagazine Mammoth Trumpet, Volume 12, Number 2, April 1997.