GEOPHYSICAL SURVEY AND GEOARCHAEOLOGICAL ASSESSMENT OF THE OLDEST HOUSE IN BOSTON, MA

During October 2007 a research team assembled to assess the past environments of the land on which the Blake House is currently located. The Blake House, constructed in 1641, is the oldest house in Boston. It was moved to its current location during a conservation effort in 1895. Presently, the house sits on a small triangular lot in Dorchester which is a part of a Commonwealth of Massachusetts park. This location is approximate 0.25 miles north of the site of the original meeting house for Dorchester dating to 1632. The land that is today's park was once the Dorchester Commons, a large open space. During colonization, there were several small ponds on the Commons. None of the ponds remain today. All were filled to create land for development and the Commons slowly disappeared. Based on historic maps dating to 1660, one of these ponds, Great Pond, should be located in close proximity to the Blake House.

The property was surveyed with a Mala GeoSciences GPR system utilizing 250 and 500 MHz antenna arrays coupled with a Trimble GeoXH GPS for geo-location. Survey lines were orientated parallel to and perpendicular to the local slope. Conveniently, this orientation matched the long and short axes of the house. A basic leveling survey was conducted to provide elevation information to topographically-correct the GPR data.

Post-processing and interpretation of the GPR data have revealed several interesting features. A large area of chaotic reflectors with large, point-source reflections was observed in front of the Blake House. This feature persisted over approximately 60% of the front yard and is thought to continue off-property below the adjacent street. This feature has been interpreted as anthropogenic fill associated with pond filling. Several linear anomalies were also identified. Two of these are orientated perpendicular to the street and traverse the front yard. These are interpreted as utility lines. A third was located that cross cuts the property obliquely. It occurs below the fill and disturbed landscape layers. It is persistent throughout the extent of the park. Based on its orientation, stratigraphic position, and historical documents, it is tentatively interpreted as remnants of a stockade that may have surrounded the commons and meeting house during early colonial times. Ground truthing of features is ongoing.