One site in particular, now partially covered by a park road, came under special consideration as a possible forgotten slave cemetery. It wasn't far from the depressions in the ground that were then already known. Last year, when Reeves brought cadaver-sniffing dogs to investigate the claims, the stories grew more plausible. That's when he called on McGary, who works at James Madison University. Over weekends throughout the summer and fall, McGary been scouring the property with ground-penetrating radar.

McGary's investigation site is only a short walk from the Madison family cemetery. And though that plot has been lovingly restored and maintained by the National Trust for Historic Preservation and groups such as the Daughters of the American Revolution, the slave cemeteries at Montpelier — like those throughout the South — have been largely neglected and forgotten over the decades.

"Part of the reason we do this is because its geophysics, and that's what I do," says McGary, who earned a Ph.D. at the Massachusetts Institute of Technology for untangling the volcanic system of Mount Rainier in Washington state. "But part of it is also trying to kind of give voice to a community that was silenced. I think there's a movement right now — sort of a recognition that these parks haven't done the kind of job that they ought to be doing."

There's nothing to mark McGary's site today, but two centuries ago or so, there was probably a funeral here. Perhaps it was at night so that friends and family from nearby plantations could join the ceremony. Here, the enslaved might have gathered as drumming and singing rose in the air around the grave of someone whose entire earthly life had played out, confined to this plot of land, the hazy Blue Ridge Mountains that marked the horizon as distant to them as the stars in the sky.