AMBROSE CLANCY PHOTO | Stephen Mrozowski, an anthropologist/archaeologist from the University of Massachusetts, at Sylvester Manor Monday morning.

Early Monday morning in the bare, bitterly cold woods of Sylvester Manor, two men were up on a hill searching for the past.

Stephen Mrozowski stared at the ground as John Steinberg dragged a squat metal box with one wheel attached over the thick leaf cover, looking at a monitor hung from his neck. They were on a wide patch of ground under white pine trees within a slatted wood fence that looked in places like an old comb missing some teeth.

“Oh, yeah,”  said Dr. Steinberg, an archaeologist. “Yeah, Steve, look at this.”

Dr. Mrozowski, an anthropologist/archaeologist from the University of Massachusetts, looked at the monitor, which was undulating with waves of lines. “Yes,” he said.

The rig Dr. Steinberg was attached to is a machine called ground-penetrating radar, or GPR, technology akin to radar or sonar. Dr. Mrozowski explained that electronic beams were sent into the ground to see if anything bounces back.

The two scientists, part of a team from the Andrew Fiske Memorial Center for Archaeological Research in Boston, were out in the Island woods surveying what is from all reports a burial ground holding graves from as long ago as the 17th century.

Anecdotal evidence says there could be as many as 300 souls interred on the fenced hillside not far from North Ferry Road. The story goes that African slaves, free black men and women and Manhansett Indians who worked at or were associated with the Manor are buried here.

Dr. Mrozowski pointed out a massive stone at the foot of the hill. Words inscribed on the stone 125 years ago are now withered by time and just legible: “Burial Ground of the Colored People of Sylvester Manor.”

The white pines standing like sentinels on the hill were planted around 1900 in the belief the sweet-smelling needles would keep the air clean and disease-free around the burial site.

The team from Boston was careful to say that something was down below, but it was too early to tell exactly what. The positive response from Dr. Steinberg’s portable GPR equipment could be picking up large rocks and not graves and human remains, Dr. Mrozowski said.

Using GPR was a non-invasive — as opposed to digging — method of finding if there are graves and then mapping them, Dr. Dr. Mrozowski said.

He’s been all over the world searching for ancient cultures, revealing tangible remains that bring us closer to the people who lived and died long ago.

He’s been on Shelter Island before. Between 1998 and 2005, as  director of the archaeological team, Dr. Mrozowski spent summers excavating Sylvester Manor’s grounds, unearthing a cultural mix of Native American, African, Dutch and English lives. In scholarly journals he’s noted that the archaeological record at Sylvester Manor is a natural laboratory to study the interactions of the various cultures that were here in the 17th and 18th centuries.

As the morning wore on it got colder, but the arrival of UMass grad students brought some warmth to the site with their chatter and energy as they raked leaves down to the bare earth.

Later in the day, a dozen Shelter Island School students came by on a field trip for their course, “History of Shelter Island,” led by teacher Peter Miedema.

But earlier, with just the archaeologists  patiently working the GPR and silently moving across the area, there was an air of mediation as well as scientific research along with a natural instinct of respect that is felt in cemeteries.

But for a cemetery, there was something missing. Wouldn’t head stones be marking the graves?

Dr. Mrozowski explained that for the class of people who would have been buried at Sylvester Manor three hundred years ago, the only markings for their lives and deaths would have been simple rocks.

He began pointing them out, colored brown and gold, partially covered with leaves, dotting the hillside.