The Application Of Geophysics To Archaeologic Mapping Of Prehistoric, Protohistoric And Historic Sites In Western Canada
Paul D. Bauman, Rod Heitzmann, Jack C. Porter · 1995
In 1799, the site of Rocky Mountain House, Alberta, stood at the southwestern corner of the northern fur empires of the North West Company and their competition, the Hudson’s Bay Company. It marked the endpoint of a yearly journey of up to 3,000 kilometers for the traders who inhabited the site. Between 1799 and 1875, four forts were constructed by the two fur trade companies. The third of these forts, which stood from 1835 until 1861, has not been excavated. As these forts were almost entirely constructed of wood, with very little metal or stone, their surface remains are meager. The goal of this investigation was to evaluate the utility of geophysics as an archaeological aid in studying such historic sites in Western Canada. Specifically, the objectives were to identify the position of the rooms and palisades of the 1835 1861 fort, and to locate burial sites associated with this and other forts. An additional objective was to explore for prehistoric and protohistoric native campsites in the vicinity of the fort. A challenging obstacle in describing the 1835-1861 fort using geophysics is the fact that in 1861, the Blackfoot peoples burned the fort to the ground. Four geophysical methods were used. Ground penetrating radar data provided the greatest detail in describing fort construction and burial locations. The GPR data, however, would have been of limited use if not viewed in conjunction with the information provided by total magnetic field, magnetic gradient, and terrain conductivity plots of the particular sites. The integration of the various methods provided an overall plan of the original construction of the 1835 fort, including some unexpected insights into the building techniques of the period. While GPR most clearly pinpointed several burial sites, the use of multiple instruments provided greatly increased certainty and an increased understanding of the nature of the identified graves. Beyond being a good example of an archaeogeophysical data set, the significance of this paper is the clarity with which it is shown the need to integrate a number of geophysical techniques at investigations of historic sites in Western Canada. In addition, it is evident that the spatial relationships of buildings, burials, and palisades provided by a detailed geophysical data set can greatly enhance the overall understanding of the activity and history of a fur trade post during its active life.