North American Database of Archaeological Geophysics
North American Database of Archaeological Geophysics
Abstract/Summary:
Project Name: Mill Lake Island Geophysical Survey;
Reference: Jeandron, J. (2003) Geophysical Survey of Mill Lake Island. MS on file. Archaeological Prospectors, PO Box 20042, Fredericton, New Brunswick, E3B 6Y8.
Field work was conducted on August 03, 2003. The magnetometer survey was conducted using a Bartington 601Grad fluxgate gradiometer magnetometer with a vertical sensor separation of 1m (depth of scan is up to 3m). The lowest sensor was 30cm above the ground. The instrument was zeroed at a location away from any noticeable disturbance at the beginning of the day and before each grid was surveyed. Only 10m x10m grids were surveyed, each at 1m traverses with readings every 12.5cm. The data logger was set with a sensitivity of .1nT (nanoTesla). As preliminary archaeological testing had been conducted here in the past, the geophysical survey grid was established using previous datums. Ten 10m2 grids were laid out along the beach, with Grid 1 directly south of the Island and the remainder laid out adjacent to each other in a westerly direction. The relatively narrow beach and its orientation controlled the placement of the grids. A small watercourse intersects the beach which necessarily ended the line of grids, however, a further three 10m x 10m grids were continued on the western side of the watercourse. Grids were surveyed beginning in the southwest corner, heading north, and walking in a parallel formation. This beach formation includes many different layers of peat which have been exposed in places. Some of the anomalies are suggestive of variations of peat density and depth. The identified and suspected hearth features measure about 70nT but Grid 1 has been clipped to -10nT and 10nT. The hearth feature furthest west was partially excavated and radiocarbon (AMS) dated to 6200 to 5990 BP (calibrated). It is assumed that the relatively high clay content has increased the visibility of these thermoremanent features. Artifacts of this period have also been recovered from this site.