The thing is, nobody's sure:

University of Georgia archaeologists have been puzzling over finding an apparent manmade object buried in a historic Civil War cemetery.

Ground-penetrating radar on parts of Myrtle Hill Cemetery, listed on the National Register of Historic Places, found a reflection that did not look like a grave during a scan of two Civil War grave sites earlier this month.

"There definitely is something manmade there, something big and metal," said Sheldon Skaggs, a member of the archaeologist team. "Now we have to determine what it is."

Which shows that the field has indeed come a long way in the past twenty years. When I was an undergrad, the first step in the survey would've been to hammer a rod into the ground in a regular pattern. That would've revealed a solid mass, and its rough outline. The next step would've been to dig some small exploratory trenches (oftentimes with a backhoe, for speed). If that revealed anything interesting it'd be off to the lab and offices to gin up a grant proposal to fund a full dig.

Nowadays it would seem they pay a few grad students to drag a lawn mower-sized gizmo back and forth, and then work from that. Ain't technology grand?