Map Artifact Concentrations for Highway Impact Assessments

Archaeologists used Surfer to map the distribution of artifacts at two historic homesteads in the path of a proposed highway expansion project. Mapping of objects excavated at the sites helped the team better understand their historical significance and evaluate their eligibility for listing on the National Register of Historic Places.

The transportation project in question was the Pennsylvania Turnpike’s Southern Beltway expansion near Pittsburgh. As part of the National Historic Preservation Act, the Turnpike Commission contracted with Cultural Heritage Research Services Inc. (CHRS) to perform an archaeological impact study of abandoned home sites dating from the late 1800s which could be demolished to make way for the Southern Beltway.

“Our most intensive investigations focused on two home sites, one occupied by a mining family and the other by farmers,” said Corey Hovanec, Archaeology Project Manager at CHRS based in Lansdale, Penn. “Both are proposed for total demolition.”

The objectives were to recover as many artifacts as feasible and identify all in situ features at the two properties, which are located less than a mile apart, to learn more about the daily lives of the families who lived there. Ultimately, CHRS wanted to determine whether the sites contributed historical information of importance to understanding the culture of the residents in rural western Pennsylvania a hundred or more years ago.

Presenting such historical detail in map form helps with this understanding and facilitates in establishing eligibility of a site for inclusion in the National Register, Hovanec explained.

The CHRS team divided each property into grids with 20-foot spacing and began digging for artifacts. They ultimately found approximately 32,000 and 33,000 objects at the farmer and miner homesteads, respectively. The items included tools, toys, ceramics, bottles, buttons, nails and numerous other artifacts that provided insights into the daily lives of the families who once lived there.

“Artifacts tell us about the family’s socio-economic status based on the things they buy or discard,” said Hovanec. “You can learn a lot [from the artifacts] about the differences between mining and farming families.”

CHRS mapped and interpolated the 2D grid distribution of the artifacts in Surfer to examine patterns. Among the most important information revealed was the function of various buildings, now just foundations, on the sites based on concentrations of certain types of objects. Ceramics and cooking implements, for example, pointed to the existence of a summer kitchen, while hardware and tools could identify a workshop.

“The interpolation function is the biggest asset Surfer provides us,” said Hovanec, explaining that archaeologists typically can’t excavate every inch of a site. Instead they map on a grid and then rely on the mapping software to fill in the spaces and provide a complete overview of artifact density and distribution patterns.

“We could have done this in GIS, but Surfer offers an easy way to do what would otherwise be complicated,” said Hovanec.

CHRS completed the assessment of the two historical homesteads and recommended their eligibility for listing on the National Register. Their status is currently pending.