THOMASTON, Ga. — The old dead lie beneath a noxious carpet of brambles and poison ivy, their tombstones mostly shattered, their names obliterated and long forgotten. The graves of the recent dead, fresh mounds of ochre clay, are equally anonymous, without a single stone or marker among the strewn beer cans and candy wrappers.

Hundreds of people — or perhaps more than a thousand, no one really knows — are buried in this single acre of sloping earth. Former slaves, sharecroppers, teachers and preachers who lived in Thomaston's black section in the 1860s lie beside modern-day indigents brought here by funeral homes. Local records show that impoverished Confederate veterans were buried here, too, but their headstones are nowhere to be found.

Old Mill Cemetery, as it is known, is a no-man's land of the dead. Diane Caldwell comes here once in a while to tear out saplings and vines, but she knows nature has the upper hand.

"I go through this cemetery, and I can feel people crying out for help," said Caldwell, 38, a genealogist who lives a few miles outside this faded mill town of 9,400 people. "They're saying 'Please don't forget us.' "

But there are thousands of graveyards like this across the South. From North Carolina to Arkansas, time, development and neglect are swallowing abandoned cemeteries, historians and preservation groups say.

The Mississippi Heritage Trust, alarmed by the destruction and disintegration of so many historic burial grounds, recently included a handful on its list of the state's most endangered places.

In Montgomery County, Tenn., a local historian estimates that there are as many as 500 lost or abandoned black cemeteries in the county. And in Palatka, Fla., the Francis Community Black Cemetery was recently paved over for the parking lot of a fast-food restaurant.

Glenn Jones, who runs a cemetery preservation group in Benton County, Ark., said he believed that a dozen graveyards in his state were buried beneath asphalt each year. When he complained to a local developer, Jones said, he was told, "Life is for the living, not for the dead."

The old cemeteries are under siege on several fronts. Suburban developers are taking advantage of weak laws or lax enforcement to bulldoze them. Vandalism laws provide little protection — in South Carolina, for example, those prosecuted for destroying abandoned cemeteries must be shown to have done so "willfully and intentionally," a difficult burden of proof.

In most states, disused cemeteries are legal orphans, ineligible for public money that might rehabilitate them. And strapped state and county governments seldom get involved.

"I get a few calls a day from people who ask for our help, but the most I can do is tell them, 'It's your project,' " said Ken Wilson, a historian with the Historic Preservation Division of the Georgia Department of Natural Resources. "I mean, there are thousands of these cemeteries across the state."

But preservationists say the most imperiled burial grounds are those historically used by African-Americans. Part of the problem, they say, is that 18th- and 19th-century graveyards were often poorly marked, their occupants too poor to afford lasting monuments. In many places, the vast 20th-century migration of blacks to Northern cities depopulated many rural Southern towns, leaving black cemeteries hopelessly neglected.

And throughout the South, the traditional days of cemetery tending, family events in the spring and fall, have long since been eclipsed by modern life.

"People have become so busy, no one has time to travel four or five hours just to clean up the family grave," said Christine Van Voorhies, a historic preservationist and the author of a how-to guide for cemetery maintenance called "Grave Intentions."

Not all the neglect, however, is entirely benign. In some cases, local authorities may be less vigilant in maintaining black cemeteries than white ones, said Michael Trinkley, an archaeologist from South Carolina who frequently testifies in cases of grave desecration. Compared with the neatly planned and monument-filled cemeteries established by white communities, black burial grounds were rarely conceived as manicured places, and in most cases, were relegated to the least desirable parts of town.

"Black cemeteries are easier to overlook, whether intentionally or unintentionally," said Trinkley, the director of the Chicora Foundation, a nonprofit organization that advocates the preservation of historic cemeteries. "Still, if we were seeing as many white cemeteries destroyed, people just wouldn't stand for it," he said.

In 1994, when David Paterson decided to compile a history of black Thomaston's transition from slavery to Reconstruction, he was surprised to find that the local historical society had produced three volumes on white cemeteries but nothing on black ones.

"When I asked why the books didn't include black cemeteries, the answer I got was, 'We couldn't find any blacks interested in copying headstones,' " said Paterson, an amateur historian. "I didn't know it took black people to copy black tombstones."

The steady degradation of Thomaston's Old Mill Cemetery, which sits a few blocks from the city's historic square, began in the 1950s, when the last of the original trustees died. Still, workers from Thomaston Mills, a textile plant that nearly envelops the site, did their best to keep the briars at bay until the company went under four years ago.

"We would cut the grass because it was the courteous thing to do," said George Hightower, 54, whose family founded what, for a century, had been the city's largest employer. Local residents tried to get the city and the county to take over the cemetery but were politely rebuffed.

When one of Thomaston's black undertakers, Johnny Enoch Bentley Jr., tried to raise restoration money through his Sunday radio show, only $150 came in. "Just about everyone in town feels there's no hope for doing anything about that cemetery," said Bentley, 77, who has buried 4,000 people over the past four decades. "It's just a lost, lonely place in the minds of most people."

That has not stopped Bentley and his two competitors from using it as a potter's field, with about a dozen interments a year. Bentley, for one, thinks there is room for as many as 200 more. "The colored people of Thomaston own it," he said. "Who can say anything?"

Caldwell, the genealogist, has been saying plenty. She accuses Thomaston's funeral directors of casting aside old headstones and graves to make room for new interments. Bentley and the others deny that accusation.

"This cemetery has long been filled," Caldwell said on a recent Sunday, whacking at the underbrush as a cold rain fell. "This is downright disgraceful."

Her goal, she said, is to stop burials, put a fence around the grounds and form an organization to restore the cemetery. She and others also want to solve one of the mysteries of the Old Mill Cemetery: What happened to the graves of the Confederate soldiers? The original deed, filed a year after the end of the Civil War, described the grounds as a final resting place for "soldiers only."

Penny Cliff, the Upson County archivist, said she found it hard to believe that Thomaston's white citizenry would have allowed the intermingling of soldiers and former slaves. The theory of some local historians is that the bodies of the soldiers were moved to another cemetery here.

Citing the stories of his father, who died recently at the age of 85, Hightower, the former mill owner, believes no body has ever been removed from the cemetery. "If they're buried there," he said, "they're still there."