Heritage recently conducted a combined GPR and Magnetometer survey of a portion of the Barnes Museum grounds in Southington, Connecticut. The Barnes Museum, a Greek Revival Style Homestead, was built in 1836 for Amon and Sylvia Bradley. The Bradley/Barnes family inhabited the homestead until it was bequeathed to the Town of Southington in the 1970s. While the homestead originally served as a farm, much of the property was altered significantly in the early 20th century, when the formal gardens were constructed. Historians at the Barnes Museum also indicated that an earlier 19th century clock factory may have been located within the property grounds. The museum is planning to expand it's limited parking area, and Heritage conducted geophysical surveys to determine if any archaeologically sensitive features are intact within the parking expansion area.
The results of the GPR survey provided compelling evidence for the presence of a large building within the southern portion of the museum property, as well as pervasive 20th century landscaping/garden filling activities. GPR evidence indicates two separate portions of the building are preserved, including a series of 15 wooden piers/footings, likely the base of an elevated portion of the building, or some ancillary portion of the structure. These piers are shown in a three separate rows of five (or five rows of three) in the image below in plan view, as well as in a single GPR radargram (or profile) transect to the left, which displays three of the piers, as indicated by the black and red arrows. The position of the GPR transect is indicated by the red directional arrow on the plan view map, which perpendicularly bisects each of the piers shown.
Lying adjacent to the piers/footings area, and directly to the south, was a large, rectangular(ish) structure, more deeply buried than the piers. This structure is quite large, at over 20 meters in length and 10 meters wide, and most likely represents the foundation remnants of the industrial building on the property prior to the construction of the Greek Revival house by Amon and Sylvia Bradley. The red directional arrow on the plan view displays the position of the GPR profile to the left, with digitized examples of two exterior wall foundations, as well as the general cellar area of the structure.
Heritage also conducted a magnetometer survey of a portion of the property to determine if any additional features could be detected geophysically. The site setting of the Barnes Museum presented some limitations to traditional magnetometer survey, as there were numerous ferrous/magnetic materials at the site, including a long fence and municipal parking lot near the survey. Due to these magnetic interferences, only a small subsection of the GPR grid was surveyed.
Magnetometer results were less clear than the GPR survey, due to surficial magnetic interference, as well as a buried utility line in the northern portion of the grid area. However, a portion of the magnetometer survey did overlap with the predicted location of the building footprint, and the magnetometer results indicate elevated readings (measured in nanoteslas) with the cellar fill portion of the survey area. The overlap in GPR reflections and magnetometer results is displayed below in identical spatial transects of the magnetometer survey (upper left) and GPR survey (lower left). The position of these transects is again indicated by a red directional arrow in the plan view map of the magnetometer and GPR amplitude maps. Magnetometer results display a clear correlation with the cellar fill from the GPR amplitude map, as well as the buried utility line.
These results provide compelling evidence for the potential location of a buried foundation on the property that predates the Bradley estate. The survey also shows that it can be useful to conduct magnetomer surveys in challenging urban environments, when they are paired with GPR or some other geophysical technique. In the near future, Heritage archaeologists will excavate judgmentally placed shovel test pits to ground truth these results, and help the Barnes Museum and the Town of Southington plan their improvements to the property.