The thermal infrared survey of New Philadelphia yielded a number of anomalies that may be related to the nineteenth-century occupation of the site. Only subsurface testing can fully explain these. The success of the survey may be limited by the ground cover at the site. To give thermal infrared surveys the greatest chance for success, data should be collected in bare earth or, if that is not possible, the vegetation should be short and even across the survey area.
The results of the thermal infrared survey conducted in May 2008 by Bryan Haley and Tommy Hailey were partially investigated through ground-based excavation work in an Archaeological Field School conducted at New Philadelphia in the summer of 2008. A more systematic testing of the precise locations of the aerial thermal anomalies identified by Haley and Hailey will be undertaken in future field seasons through targeted ground-based geophysical surveys, soil core sample surveys, and excavations. The New Philadelphia Archaeology Project sponsors summer field schools for such ongoing investigations, with funding support from the National Science Foundation’s program of Research Experiences for Undergraduates (for 2008- 2011).
Examining the data results of identified thermal anomalies depicted in Figure 3 above and in GIS data images provided by Haley and Hailey, our excavation team has observed a number of instances in which the locations of thermal anomalies appear to correlate with the known locations of sub-surface foundation remains from past residences located within the town site. These correlations will be further analyzed and tested in upcoming field seasons.
Separate from this project supported by the NCPTT, Bryan Haley also served as a geophysical consultant with Time Team America’s staff who investigated portions of Block 8 of the New Philadelphia town site in June 2008 in a search for the foundation remains of a small school house that served African American children in New Philadelphia in the mid-1800s. In addition to testing various forms of ground-based geophysical surveys conducted for the Time Team project in Block 8, Haley also analyzed the thermal infrared data in that area and the Time Team archaeologists ground-tested promising locations with excavations. A report on the results of Time Team’s work on Block 8 is provided in Chapter 5 of the 2008 New Philadelphia Archaeology Report (Fennell 2008b).
Field school participants in the summer of 2008 also investigated an area of comparative data between ground-based geophysical surveys and the aerial thermal survey in the area platted as King Street along the north edge of Block 8. As discussed in Chapter 6 of the 2008 New Philadelphia Archaeology Report (Fennell 2008b), an electric resistivity survey conducted by Michael Hargrave (2006) showed a clear alignment of anomalies running east to west along the space of a side street within the town plan. This location was covered by a stone and gravel stretch of narrow roadway in a 1939 aerial photograph, but is today covered entirely in agricultural soils and vegetation, with no visible remains of the road on the ground surface. The thermal infrared survey did not produce data indicative of anomalies that would correlate with the space and configuration of such a roadbed. Excavations in the Summer of 2008 in a sampled space of the resistivity anomalies in King Street revealed a lens of gravel and stone from an early 1900s roadbed buried 1 foot below the current ground surface, and, beneath that, the remains of a late 1800s packed dirt roadway with wheel rut depressions. In comparing the thermal infrared data with the ground-based electric resistivity data, it is notable how clearly the remains of the road appear in resistivity survey results but not in the thermal infrared results. As we continue to investigate the thermal infrared anomalies in future field seasons, it may become clear that this aerial survey method is highly valuable and cost-effective for locating the buried remains of foundations to buildings, but cannot detect the more subtle remains of town infrastructure elements, such as buried roadbed remains.