The Mother Bethel ground occupies about a quarter-acre at the southwest corner of the three-quarter-acre playground at Queen and Lawrence Streets.
The archaeological report, based on test excavations in July and analysis of city records, has compelled the city to delay scheduled renovation of the cemetery portion of the playground area while civic and religious leaders determine how to address memorialization.
The test digs encountered grave shafts and coffin wood less than two feet below ground. Even a gravestone - for Amelia Brown, who died in 1819 - turned up.
Plans for a public meeting are in the works and officials are preparing for what promises to be a lively and perhaps contentious discussion of commemoration possibilities.
"This is a playground," said Mark Focht, deputy first commissioner of parks and recreation, speaking of the whole Weccacoe Playground site. "This has been a playground for a very long time. We have to figure out how these two things . . . can coexist."
Focht said installation of new playground equipment, a storm-water management system, and other enhancements will probably commence in late spring of 2014.
The cemetery, which had languished in obscurity for a century, was put on the city register of historic places in June, and the archaeology study was ordered in advance of renovations to the now-protected site. (All construction related to a protected historic property must be approved by the city historical commission.)
The Rev. Mark Tyler, the pastor of Mother Bethel who will convene the public meeting on memorialization, said he had no time limit in mind for that process.
"To me, it's about getting it right, not getting it fast," he said. "You can't have this kind of ground-breaking information and then move quickly on."
He envisions "a public meeting where anybody with an interest can come and express themselves."
The cemetery is the first private burial ground for African Americans in Philadelphia. The land was purchased in 1810 by Richard Allen, founder of the church, and was in use until the mid-1860s. It served as the resting place for much of black Philadelphia's founding generation, as well as for thousands of indigent and poor who packed what was then known as Southwark.
The ground fell into dilapidation in the 1870s, and the church sold it to the city around the turn of the 20th century. Since then, the cemetery has been a community garden and a playground.
About nine years ago, Terry Buckalew, an independent historian, began researching the burial ground and has now documented about 1,600 individuals interred there, a fraction of the whole, many with no affiliation to Mother Bethel.
(Buckalew's research is available at http://preciousdust.blogspot.com.)
He said the archaeological report, prepared by URS of Burlington, documents "beyond a shadow of a doubt that we have a major historical finding."
The Bethel ground is not the largest ancient burial place for African Americans in the nation, although it is among the largest and oldest. The African Burial Ground in New York City contains the remains of about 15,000 largely enslaved and almost entirely anonymous Africans.
"The earlier burials [at Bethel] were the first generation of free blacks, and most or many were not slaves," said Buckalew. "Individuals who were the leaders [of the nascent African American community] were buried there."
James Champion, an original church trustee, was buried there in 1813. Stephen Laws, another church founder, succumbed to typhoid in 1814 and joined Champion.
The Rev. Richard Williams, Mother Bethel's pastor in the 1840s, and the Rev. John Boggs, whose 1848 funeral was attended by 1,000 mourners, are buried there.
Sarah Bass Allen, abolitionist and wife of Richard Allen, was buried in the cemetery in 1849, although the church maintains she was reinterred in its basement crypt.
Ignatius Beck, a former slave who helped build the U.S. Capitol building and died in Philadelphia in 1849, is buried at Bethel. Musician John Bliss, a member of the renowned Frank Johnson's band, died in 1848 and was buried at Bethel with "members of the colored Masonic Order . . . clothed in their rich regalia" accompanying the funeral, according to an Inquirer report.
Tyler, the Bethel pastor, must manage a broad discussion of how best to commemorate a spot that serves as a marker for and portrait of black America and the nation at large.
It won't be easy.
Already, various ideas are being floated - from disinterring the remains and reburying them on Independence Mall, a more public space, to acquiring the entire Weccacoe site and adjacent parking and other buildings to serve as a historical center.
Michael Coard, a founder of the Avenging the Ancestors Coalition, a key group in the decadelong effort to commemorate the President's House on Independence Mall, said he was concerned by the proximity of playground and sacred space.
"You don't play tag over the bodies of the ancestors," he said.
But Asante, the Temple professor, said it was not uncommon in West Africa for festivals and daily life to take place in and around the graves of ancestors. On the other hand, he added, that would hardly be the case in North America.
"There's no one way to look at it," he said.
Tyler, who also would like National Historic Landmark status for the ground, predicted disagreements.
"It's going to be messy," he said. "I want to have the conversation. I want to go in with an open mind."