Archaeologists find the past under our streets
Archaeologist Ryan Rowles got a little excited when he discovered remains of a pre-Civil War gristmill buried under a Washington County bridge destined for replacement.
"There's no information on excavated gristmills in this part of the state," said Rowles, a PennDOT archaeologist who documented the site as part of the bridge project. "These were pretty good-sized buildings, two to three stories high."
Such discoveries, though not routine, are the sort of thing archaeologists are finding under roads and sidewalks across Pennsylvania. They can be important teaching tools, say archaeologists who will discuss finds in July at the 2012 Preservation Combination Conference in Lancaster, sponsored by conservation groups.
"People are often shocked to learn how much we don't know about the 19th century," said Rick Geidel, president of the Pennsylvania Archaeological Council.
Finds come almost anywhere you dig in Pittsburgh, said archaeologist Christine Davis, who led crews on digs prior to construction of Three PNC Plaza, Downtown, in 2006. They recovered more than 25,000 artifacts, some buried up to 26 feet beneath Fifth Avenue. The astounding yields have to do with the city's location near three rivers, Davis said.
"There's an opportunity to have layers preserved. ... Floodwaters seal things, a lot of times," she said.
Rowles' "significant finds" include an arrowhead, ceramic pottery shards and small pieces of waste material produced during the manufacture of stone tools.
The water-powered gristmill was less than 4 feet beneath the ground, said Rowles, 33, of Scottdale. Part of it extends beneath Route 221. Some remains of mill architecture and stone walkways were intact.
More than 1,500 artifacts were turned over to the Pennsylvania State Museum, including pottery such as creamware, yellowware and rockinghamware.
"I'm beginning to wonder just how effective we are in erasing the past," Marc Henshaw, an industrial archaeologist who runs a consulting business.
Thomas Westfall was 12 when his father bought the gristmill in the 1940s, one of three grist and saw mills located near Taylorstown, and converted it to a feed mill and automotive repair shop. In 1963, he used lumber from the mill to build his house nearby.
"I tore it down board-by-board," said Westfall, 79. "It took a year."
Susanne Haney didn't expect to find a more than 200-year-old well with a nicely preserved wood pipe inside when digging beneath a Blairsville sidewalk that was being replaced.
"This was an unanticipated and exciting find," said Haney, a PennDOT archaeologist. "You run into wells ... but not that large and intact with a wood water pipe."
Before workers poured the previous sidewalk, the 30-foot well had been capped with a large steel plate that helped preserve the pipe, believed to be made of oak, Haney said.
In Brownsville, Henshaw is working to uncover remains of John Snowdon & Son's Vulcan Iron and Machine Work. The foundry began operations in 1824 and lasted until the late 1880s, employing more than 200 people at its peak.
"It's probably one of the most exciting (digs) I've been involved in," said Henshaw, 36, of Brownsville. "This is the place that built the first cast iron bridge in America."
More than 300,000 pounds of iron went into building the Dunlap Creek Bridge in Brownsville between 1836 and 1839.
"An almost oxygen-free environment" preserved the foundry, located under concrete and railroad fill, Henshaw said. Artifacts uncovered there include large rivets, bottles, iron castings and tools.
"This site is incredibly important to the industrial heritage of Brownsville and the Mon Valley," said Henshaw, who hopes such efforts help "educate the public about what's beneath their feet."