New Answers to Old Questions
Most people probably wouldn’t have noticed it, but farmer Harold Conover in 1988 happened to see a stone spear point in the sand on a logging road near his farm in Carson, Va.
That chance discovery triggered a decade-long excavation that eventually may resolve the ongoing, often bitter controversy over when humans first migrated to North America.
The spear point itself wasn’t unusually old, but it led archeologists Joseph and Lynn McAvoy to a prehistoric campsite that may be as much as 17,000 years old--or 5,500 years older than the so-called Clovis sites thought to be the oldest on this continent.
The findings indicate that humans have lived here much longer than researchers previously believed and hint that their origins may be different from what had been believed.
Other archeologists have, of course, made similar claims for a number of sites in both North and South America, some apparently dating as far back as 35,000 years. But the dating of those sites, as well as the validity of the artifacts found there, have always been questionable.
But data presented last month by Joseph McAvoy and a team of archeologists at the Society for American Archeology meeting in Philadelphia seem to have firmly established the age of the Virginia site, called Cactus Hill.
“This one looks real,” McAvoy said, and others agree. “This is probably some of the oldest material in North America, if not the entire New World,” said archeologist Dennis Stanford of the Smithsonian’s National Museum of Natural History.
The Cactus Hill site is one of several that are overturning the long-reigning theory of how humans first came to the Americas. Archeologists have always assumed that the first inhabitants walked across the Bering Strait to Alaska when ice covered its surface about 12,000 years ago.
Those first migrants quickly moved south, expanding their presence throughout the continent within as little as 500 years. That population is termed “Clovis” because the first remnants of its existence--fluted spear points and other tools--were discovered at a site near Clovis, N.M. The distinctive Clovis spear points have since been found throughout the continent and, recently, in northeastern Asia as well, affirming the origin of these nomadic hunters.
But the story has been growing more complicated. Some archeologists have identified other sites, such as the Meadowcroft rock shelter in Pennsylvania and the Topper site along the Savannah River in Georgia, that appear to be pre-Clovis. Their dates, however, have not been firmly authenticated to everyone’s satisfaction.
Others have found evidence that other populations may have migrated to the continent as well. Recent studies suggest that a seafaring population worked its way down the Pacific coast, establishing villages and fishing grounds on land that is now submerged. Some archeologists believe that the same process occurred along the Atlantic coast as well.
But the dates of such events have always been questionable, and that is why the Cactus Hill site has assumed such importance. The McAvoys and their colleagues have produced dating evidence that may well be irrefutable, thanks in part to Conover’s discovery.
Although Conover is not an archeologist, he recognized the Clovis spear point he found in the road because there is a known Clovis site on his farm. He tracked the point to a sand pit owned by the International Paper Co. at the Cactus Hill site,
about 45 miles south of Richmond and overlooking the Nottoway River. Cactus Hill, which takes its name from the prickly pear plants that cover it, is basically a large sand dune held together by clay and silt.
Conover contacted the McAvoys, who run what Joseph McAvoy calls a “mom and pop archeological business” out of their home in Sandston. With support from the Virginia Department of Historic Resources and, eventually, the National Geographic Society, they began excavating at Cactus Hill in 1989.
About 23 to 30 inches below the surface of the dune, they found a campsite containing an ancient hearth, scrapers, woodworking tools and several Clovis spear points. Radiocarbon dating of charcoal from the hearth showed it to be about 10,900 years old, appropriate for a Clovis site.
Digging further, they were surprised to find a second campsite about four to six inches lower, again with hearths and stone tools. But the tools were distinctly different. Instead of quartzite Clovis spear points, the tools from the lower camp were made of chert and were of a more primitive form that archeologists call blade flakes or core blades.
Just looking at the tools, “it really wasn’t a very hard call” to say that the lower camp was much earlier in origin, McAvoy said. Radiocarbon dating revealed three years ago, in fact, showed it was at least 15,000 years old and perhaps as much as 17,000.
Team of Specialists Evaluates Findings
Skeptics scoffed, however. It’s easy, they said, for charcoal from one layer of the soil to be carried to another layer by storms or burrowing animals. And that date contravened the prevailing wisdom.
Stung, McAvoy organized a team of at least 10 specialists and spent the last three years “challenging the conclusions” of his original report.
Paleobotanist Lucinda McWeeney of Yale, for example, identified the species of trees that were burned in the hearths. The pre-Clovis hearth contained remnants of white pine, while the Clovis hearths contained hard Southern pine. Trees in the area now are primarily hardwood hickory and oak. That progression of species corresponds with the gradual warming of the region since the last ice age.
She also was able to show that the charcoal in the lower hearths was not produced by a forest fire.
Soil scientist James C. Baker of Virginia Tech used a technique called luminescent dating to show that the sand at the site had not been disturbed over the millenniums, suggesting that perturbation of the site by water or burrowing animals had not occurred.
Others were able to demonstrate the presence of distinctive plant fossils, called phytoliths, produced when plants on the surface are damaged, as by human activity. The amounts of phytoliths spiked at the levels of the campsites. The team also found high levels of phosphates in the soil at the levels of the sites. Phosphates are the detritus of human wastes and garbage.
“To me, the evidence is irrefutable,” McAvoy said.
And who were the pre-Clovis settlers? “My first answer would be paleo-Indians who came across the Bering land bridge” earlier than had been thought, he said.
But the Smithsonian’s Stanford has a different idea. He thinks the tools are remarkably similar to somewhat older tools recently discovered in Spain and France. He suggests that those proto-Spaniards may have sailed across the Atlantic 18,000 years ago or more.
Not everyone is convinced. Archeologist David Meltzer of Southern Methodist University, for one, questions the fact that the two campsites, separated in time by several thousand years, are separated in space by only three or four inches. “There should have been more soil-forming processes over that period,” he said, so that the early site was more deeply buried. McAvoy’s findings, he said, “are impressive, but they don’t quite seal the case for me.”
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Thomas H. Maugh II can be reached at thomas.maugh@latimes.com
