But many diseases don't leave evidence in the bones. "High fevers, things . . . [that] kill you really quickly," don't leave time for the bone to react, she said.
"Kids get sick so quickly," she said. "You get a high fever [and] it can kill you in a matter of a day, two days, three days, and that won't show up on the skeleton."
Volunteer John Imlay and Easton High School biology teacher Nicole Barth examine a skeleton.
(Gerald Martineau -- The Washington Post)
Still, the bones were extremely well-preserved, probably because the soil was dry and well drained. "The preservation is just amazing for this time period," she said. "Getting a skeleton where you can take out the bone is good," she said. "Usually you just have a stain in the soil that would show you the position of the body."
Aside from bones, coffin nails were the main artifacts the group was finding, until about 3:40 p.m., when volunteer archaeologist John Imlay found another object near the pelvis of the young man in grave B-3.
"It's brass," he called to Owsley.
"Where's it coming out?" Owsley asked.
Right around the skeleton's crotch, Imlay indicated. It looked like some kind of fastener.
Did the individual have pants on? Owsley asked.
Imlay wasn't sure. But moments later, he found a second, similar object, this time with something attached. Owsley examined it. "That's fabric," he said, a terrific find that, under a microscope, might help date the burial.
As the day waned, and a giant moon began to rise on the horizon, attention focused on grave B-7. Its occupant probably was in her late teens or early twenties and had unusually healthy teeth, said Prince George's County archaeologist Dana Kollmann, who was working on the bones.
When Owsley climbed into the pit for a closer look, he said he had been thinking that the skull of the man in grave B-1 also looked African. He could tell by features of the face and jaw. Three tiny hoops later would be found with B-1's skull.
As he pondered B-7, turning the skull in his hands, Owsley looked as if he were waiting for her to speak, waiting for her to explain how and why she had been buried there so long ago.
Owsley eventually would exhume the bones of 12 people from the mound by the creek for study. Three, buried in shallower graves, would turn out to date from the 1850s or 1860s, he said in an interview at the Smithsonian on Thursday. He could tell by their coffin hardware.
The rest, buried together more deeply, are likely to be from the late 1600s or early 1700s, he said. But he is not yet sure.
"In archaeology, when you're digging," he said, "you never know what you're going to find. It's like a mystery. . . . I like the mystery. There's no doubt about it."