Dig reaches back 16,000 years

Campsite: In Western Maryland, an archaeologist searches for evidence that will pin down the time of an ancient settlement.

Medicine & Science

August 09, 2004|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

BOB WALL is too careful a scientist to say he's on the verge of a sensational discovery. He makes no claims beyond what he can support with hard data.

But the Allegany County soybean field where the Towson University archaeologist has been digging for more than a decade is tossing up hints that someone camped there, on the banks of the Potomac River, as early as 16,000 years ago.

If further digging and carbon dating confirm it, Wall's field could be one of the oldest and most important archaeological sites in the Americas.

"You're talking about the time period of the first settlement of the New World by human beings," said Mark Michel, president of the Archaeological Conservancy. "It would be extremely significant if it pans out."

Archaeologist Dennis Curry, of the Maryland Historical Trust, said simply: "It would be as exciting as hell, I'll tell ya."

He said Maryland has only one thoroughly excavated and documented site - the "Higgins" site near Baltimore-Washington International Airport - that comes even close. "There's paleo-Indian material there," Curry said. But none of the Clovis points and tools found there is older than 10,000 years.

For now, the true age of Wall's find is still in doubt.

Three radio-carbon dates taken from organic matter found in the buried soils all suggest the site dates to roughly the same time - 14,000 BC. But another, derived from charcoal found beside an ancient hearth found at the same depth, was pegged to "only" 7,000 BC.

"Not as old as we thought," Wall said. "But there's still some question about how old this is. We've got some conflicting dates now, so what we need is a good charcoal sample [for more carbon dating] and a diagnostic artifact" - a tool or other object whose design clearly shows its age.

The discovery of a human presence in Maryland in a period anywhere near 14,000 BC would throw fuel on a raging debate among archaeologists: When was the continent first peopled, and by whom?

As word of Wall's early dates trickled out to other scientists, he started hearing from them. One e-mailed, "I hear you're getting some early dates. ... What's going on?"

"I have to tell them, `Don't get too excited,'" he said.

For decades, Curry said, archaeologists were taught that the first humans came to North America after the end of the last Ice Age, about 13,500 years ago, crossing a "land bridge" from Asia into what is now Alaska.

They quickly spread across the continent, the theory proposed. And their presence has been recorded by the beautiful stone tools they left behind - all younger than 13,500 years. Their tool technology was named "Clovis" for the New Mexico town where it were first described.

But in the past decade a handful of excavations in the eastern United States have turned up traces of different tools and encampments buried beneath the "paleo-Indian" sites of the Clovis people. So they're presumed to be older, or "pre-paleo."

For example, burned wood found with tools at a Virginia site called Cactus Hill, south of Richmond, was dated to 18,000 years ago. Spear points and bone found in a rock shelter at Meadowcroft, Pa., near Pittsburgh, were up to 19,000 years old. There are a handful of others.

But all such finds have been controversial. Skeptics argue that the sandy soil at Cactus Hill might have allowed ground water to mix older organic matter with much younger artifacts, which would fool carbon-dating technology.

And the layering of deposits in rock shelters is notoriously complex. Meadowcroft's excavators might have simply confused older layers with younger ones.

But a pre-paleo find in Wall's bean field in Western Maryland would be harder to dispute, Curry said.

On the floodplain where Wall is working, silt is deposited by the river, and the soil builds up over time. Any dropped artifacts are buried in simple, stable horizontal layers, with the oldest buried the deepest. "It's a very good site ... for trying to prove a case for this pre-paleo stuff," Curry said.

Wall, his students and volunteers have been digging in the Potomac floodplain near Pinto since 1987.

Called the "Barton" site, it has been an extraordinarily rich and important find. In 2002, the New Mexico-based Archaeological Conservancy spent $96,426 (including $50,000 from the Maryland Historical Trust) to buy and preserve 31 acres of it forever.

People have lived there off and on for millennia. A Clovis projectile point found on the surface decades ago by an amateur collector testifies to paleo-Indian occupation thousands of years ago, Wall said. His own digs have turned up fragments of limestone-tempered "Page" pottery used by hunter-gatherers and early farmers between AD 900 and the 1300s.

By the 1400s, a stockade village appeared, built by people who hunted, fished, gardened and used shell-tempered "Keyser" pottery.

Next came a Susquehannock Indian settlement, built alongside the vanished Keyser village in about 1600. They were gone by the 1620s, driven out, perhaps, by smallpox epidemics.

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