For years now, Towson University archaeologist Robert Wall and his team of serious amateurs and students have journeyed down the gravel road to this quiet place in western Allegany County, between a bean field and the river.

And slowly they have sliced down through the layers of earth and time, to discover the stories of this place, and the people who were here -- right here -- perhaps as long as 16,000 years ago, sitting around a fire during the last Ice Age.

Their findings, though still being tested, have the potential to overturn long-held theories about the origins of the earliest humans on the continent.

"We keep finding things, deeper and deeper," says Wall, heading back down into a hole, now six feet deep, to study a patch of reddened soil, perhaps the remains of another ancient hearth here at what is called the Barton site.

Radiocarbon dating of charcoal found elsewhere on this site has suggested people might have camped here and built fires by the north branch of the Potomac River, anywhere from 9,000 years ago to as much as 16,000 years ago.

Wall is cautiously hoping that further testing bears out the oldest dates. And he and his team keep digging for a "diagnostic artifact," such as a contemporaneous spear point from the Paleo-Indian period that could help prove that people lived here that long ago.

"All we need now is a nice paleo point, or pre-paleo point," Wall says.

Maryland Historical Trust archaeologist Dennis Curry has been following the project with passionate interest.

"If the dates of 16,000 [years] turns out to be true, it would be exciting, unique, earth-shattering," he says.

Such a find would challenge the theory that the first humans arrived in North America about 13,500 years ago -- after the end of the last Ice Age -- by way of a land bridge from Asia. They arrived in Alaska, the theory holds, and spread through out the continent.

Those ancient North Americans, referred to as Paleo-Indians or the Clovis people, left behind stone hunting tools with a distinctive, fluted style. The name Clovis comes from a town in New Mexico where the tools were first found.

But in these parts, there also has been a long-standing hunch that people arrived even earlier. Some tools and bones have been found in Pennsylvania and Virginia that date well before the Clovis era, although scientists debate whether the dating is accurate.

Wall and his team are hoping to find something definitive here. The work of digging and sifting the hard soil, deposited in layers for millennia by the river, is slow and painstaking. Wall, 53, has made the 21/2-hour trip from his home in Catonsville, Md., countless times.

But he and his team -- a gathering of Towson students and trained volunteers from the Western Maryland chapter of the Archaeological Society of Maryland -- continue to marvel at the secrets yielded up by this land, which has been bought and will be permanently preserved by the Archaeological Conservancy, an Albuquerque-based nonprofit group, with help from the Maryland Historical Trust.

They have found 300-year-old trade beads of blue and white glass dating back to the "contact period" when white settlers and explorers first traded with the native Susquehannock people.

They have found fragments of pottery made 1,000 to 2,000 years ago in the woodland period, when people were learning to farm and store food.

They have found 3,000- to 4,000-year-old spear points left by roaming hunters of the Archaic period.

And John Domenic, one of the devoted amateur archaeologists digging in Western Maryland with Wall, found a Clovis point sticking up out of this very bean field.

Because it was found out of context, it is not the kind of artifact that can be tied definitively to one of the layers of earth now being painstakingly dug by Wall and his team. But its distinctive style -- the point was clearly made and last used by a hunter 10,000 or more years ago -- still bore traces of the last Ice Age.

"The glacier was still up in Pennsylvania," marvels one of the team, Roy Brown of Cumberland. "There were probably caribou. And we know from excavations in Virginia, there were musk ox."

And on this warm Sunday, six feet down, Wall and his crew find a small handful of stone chips. Someone, maybe an Ice Age hunter, sat here by his ancient fire and made a tool.

"We have this hearth feature and this little pile of flakes," Wall says. "It's incredible, like someone just left."

Marian McIntyre, right, and her son Brett, 7, work with Archaeological Society of Maryland members at the Barton site dig in Western Maryland.Towson University archaeologist Robert Wall holds pieces of chert, a type of quartz, like flint, that could contain evidence of early tool-making, possibly during the last Ice Age. Robert Wall and crew members search for artifacts to prove that people lived in the area earlier than believed.