NEW YORK (CBSNewYork/AP) — Specialists using ground-penetrating radar on Staten Island have detected hundreds of previously undiscovered gravesites in an African-American burial ground that dates to the 1830s.

The New York Landmarks Conservancy announced the discovery Monday at Rossville A.M.E. Zion Church Cemetery, part of the historic Sandy Ground community that was among the nation’s first free black settlements.

Before the radar survey there were 97 known burial sites on the 1.6-acre burial ground. Conservancy President Peg Breen said another 576 were discovered by radar at an average depth of 10 feet.

“It’s a very important discovery, and only adds to the importance of caring for this cemetery, and having a wider reach of the story,” Breen told 1010 WINS’ Carol D’Auria.

Sandy Ground was first settled by African-American oystermen. More than 150 families eventually moved there.

“It was really a cultural and social center for blacks not just on Staten Island, but from towns in nearby New Jersey,” Breen said.

Yvonne Taylor told CBS2’s Elise Finch that her grandparents are buried at the cemetery, but was never sure if her great-grandparents were also buried here, but feels like she may have an answer now.

“For one reason or another, they didn’t have markers, or the markers have been destroyed over time,” Taylor said.

The community was established in the 1830s, but started to deteriorate in 1916 when pollution forced the oyster beds to close.

“This community is one of the earliest settlements, some say the oldest community established by free blacks that has been continually inhabited since its founding,” Rev. Janet Jones, the church’s pastor, said. “Many of them were oystermen in Maryland and passed laws that prevented them from owning their own oyster sloops, rather than live under those conditions they left.”

The graves will not be disturbed, but the site will be overhauled, complete with clear markings and signs explaining the historical significance of the African-American burial ground.

The current Zion Church dates to 1897 and became a major stop on the Underground Railroad for escaped slaves.

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