CAMINADA HEADLAND, La. - Cleanup after the BP oil spill has turned up dozens of sites where archaeologists are finding human and animal bones, pottery and primitive weapons left behind by pre-historic Indian settlements - a trove of new clues about the Gulf Coast's mound dwellers more than 1,300 years ago. But they also fear the remains could be damaged by oil or lost to erosion before they can be fully studied.

So far, teams of archaeologists hired by the oil giant have visited more than 100 sites and sent back a growing list of finds to labs for radiocarbon dating and other tests, though extensive excavations haven't been done. Scholars have also accompanied cleanup crews to make sure they don't unwittingly throw away relics.

The disaster that began when the Deepwater Horizon exploded in April of 2010 has highlighted the urgent need to protect the sites, but a government scientist says neither their discovery - nor the money to study them - would have come as quickly without the spill.

"We're filling in gaps. There is some pioneering archaeological work going on as a result of the oil spill," said Larry Murphy, lead archeologist for a council of government agencies and trustees overseeing the oil cleanup.

He said uncovering the sites, many of them prehistoric, represents "a great leap in cumulative knowledge" about Native Americans in coastal Louisiana, who have been less studied than their counterparts in other regions.

Still, the oil represents an added threat to an area that already was under siege from land loss and rising sea levels. Oil has contaminated some artifacts and can interfere with radiocarbon dating, a primary technique for determining the age of an object. Many shores are still scattered with tar balls.

Louisiana's state archaeologist, Charles McGimsey, said the extent of the oil damage to artifacts isn't known, but he doesn't expect it to be disastrous.

The Associated Press was given a rare glimpse of several sites in June during a guided tour of the Caminada Headland by land warden and amateur archaeologist Forrest Travirca III. The beaches are closed to the public, and the locations of archaeological sites are being closely guarded to prevent looting.

Prehistoric artifacts had been found and recorded on the headland before the spill, but not to the extent now being done. Travirca began finding more of them while keeping watch for BP's black oil last summer on a remote stretch of beach that looks onto the silhouettes of oil rigs and platforms. The headland was one of the hardest-hit spots.

"I was walking on marine shell, rangia clam shell, walking out on a point I know, when I looked down, found a pot sherd, and then I started finding more and more," Travirca recalled.

Travirca, of coastal Louisiana Indian heritage himself, works for the Wisner Foundation, a New Orleans-based public land trust that owns vast tracts of the headland. He's also a member of the Louisiana Archeological Society, and has submitted his research to it.

Travirca believes many artifacts he's finding come from middens, or mounds where families lived and buried their dead. Perhaps, he says, some of the dwellings were built along a meandering bayou that's been lost to sea level rise and land loss. Many artifacts appear to be washing in.

Archaeologists say the sites date to around 700 A.D., well before the earliest known European contact in the 1500s.

Remains of larger Indian villages are known to have existed further inland, which would make the sites here more like a suburban neighborhood, he theorized.

"To me it would have been like a small subdivision," Travirca said as he walked the sands and looked for artifacts. "You would have had three, four family units, huts; the women making pottery, the men making (weapon) points."

As he walked, pointing out tar balls left over from the BP spill, his eyes scanned the beach, awash in driftwood and trash from oil platforms and shrimp boats - hard hats, propane tanks, a tied-up trash bag full of waste from an offshore kitchen.

Amid the debris, he spotted something. He leaned over and picked up what looked like a piece of brown wood.

"That's a piece of pottery," he said, inspecting the smooth curved fragment in his hands. "You see this piece has been in the water a while. You see that barnacle right there."

So far, archeologists have limited their examination to the surface of the sites here, scouring the beaches at low tides. They have found deer antlers that probably were used as spear heads, decorated pieces of pottery and gar fish scales that might have been used as darts. Human bones have been reburied in keeping with the wishes of the Chitimacha tribe, which has links to the ancient settlements.

Richard Weinstein, an archaeologist who specializes in coastal Louisiana Indians, said sites have been documented on the headland since the 1950s. He has reviewed artifacts and evidence gathered since the BP spill.

He said the preponderance of deer bones and antlers found since the spill is fascinating because it indicates the area was once forested with ridges.

"The fact that the Indians in the area were hunting deer to the extent that these guys did makes it very interesting because the coast we have there today is busted-up marsh," he said. "There aren't that many stands of trees and vegetation left."

He said coastal Louisiana is covered in Indian mounds that were organized around a complex society. He also says they could have stretched onto land that's now offshore.

"We're not talking about a bunch of hunters and gatherers who didn't know what they were doing," he said.

BP and the archaeologists it hired through the consulting firm HDR Inc. declined to comment. They referred questions to state and federal officials.

McGimsey, the Louisiana state archaeologist, said he would like to map good sites more thoroughly and excavate where possible. Archeologists with the government BP and tribal organizations are trying to figure out what steps to take next.

As part of its responsibilities to clean up the oil spill, BP is paying for laboratory work to identify and preserve artifacts. Under the law, BP is required to restore the ecosystem it has damaged, but there is no provision to force companies to restore archaeological sites damaged by a spill, McGimsey said.

However, BP has been required to make sure the cleanup does not damage archeological sites, he said.

"Whenever the cleanup crews go out there, shoveling up tar balls, archeologists go out there to make sure artifacts aren't thrown away," he said.

With erosion eating away at south Louisiana, Travirca said it was urgent to preserve and investigate the ancient cultures that lived here. In many other places, coastal sites have been lost to the Gulf.

"We've lost insights into the who, the why, the where of these people," Travirca said, as he walked the beach on the lookout for artifacts. "Extremely little work has been done in coastal Louisiana. We've just touched the surface."