Archaeological Digging In the Digital Age
Thursday, August 2, 2007
After years of shoveling his way through archaeological digs so intense that they injured his L5 vertebra, John Rutherford made his biggest discovery sitting in a cubicle west of Seven Corners in Fairfax County.
He was scouring 1937 photographs of Centreville on his computer screen when the star-shaped outline of a Civil War fort came into view, like an intricate painting on the landscape.
The fort is invisible in contemporary aerial photos. But those early images -- 215 high-resolution pictures taken by a U.S. government photographer from the sky as part of a national agricultural surveying effort -- offer a view virtually unchanged since the end of the Civil War.
"It was mind-boggling," Rutherford said. The "star fort," in a key strategic area on an eastward path toward Washington, just appeared. "Then you walk out in the field, and then there it is . . . something you saw in a 70-year-old photograph."
The photographs stir more than nostalgia. The star fort discovery, for instance, stopped a planned housing project on the site, and the county bought the land to use to build a park. Other areas in the county that have been paved could become candidates for archaeological digs, county officials said.
The historic images have also changed the way the county vets projects. "Virtually every parcel" that comes up for zoning review is checked against the images, said C.K. Gailey, a retired Army ordnance specialist. "You didn't do that it in the past. It was way, way too hard."
Gailey has spent years adding county data into a digital warehouse that holds the 1937 images, including the locations of 3,400 historic and archaeological sites and 500 pages of hand-drawn property ownership maps from 1860, the year before the Civil War started.
"We look at what's going to be lost and how much archaeology needs to be done before it's gone, because it's going to go in most cases," Gailey said.
Inspiration to find a new way to view the county came from years of frustration with the marred paper copies of aerial photos that provided a disjointed and grease-pencil-stained picture of Fairfax's history. It was an achingly slow process to manually try to locate a specific spot by reviewing a succession of photos.
County archaeologists appealed to an official at the National Archives in College Park to dig out the original negatives of the 1937 photos, which were stored in what looked like jumbo coffee cans, and have them scanned.
Rutherford, Gailey and digital geographer Scott Sizer were handed a tantalizing hard drive full of history. But to see it in full, they needed to line up the 1937 images precisely on a picture of modern Fairfax. It was like piecing together a 400-square-mile jigsaw puzzle that had an outdated picture on the box.
Relying on roads, rivers, luck and an obsessive streak, they began laying the 70-year-old photographs over current ones. Rutherford, who made the star fort discovery about a year and a half ago, thought it would take them a year to finish. But with a swirl of labor and excited phone calls charting progress, they were done in a few months.