Cesium Vapor Magnetometers in Evaluating Archaeological Site Conditions

Understanding site formation processes and the condition of archaeological sites is crucial for addressing anthropological questions and evaluating significance in cultural resource management projects. Magnetometry has been used to evaluate the archaeological landscapes, societal structure, built environment, community organization, and activity areas of human groups (Becker, 2009), and is often the geophysical technique of choice in North American archaeology. However, less emphasis has been placed on some basic issues such as evaluating disturbance and site integrity using geophysical methods in general and magnetometry specifically. This paper discusses the methods and results of a large scale archaeological survey (15 ha) conducted at Ocmulgee National Monument in Macon, Georgia using a dual sensor, GPS guided magnetometer system to address issues of site condition. The magnetometer system was successful in identifying sources of disturbance from early excavation units and modern day utility lines and public works. The system was also useful in identifying differential destruction of the archaeological record in various parts of the site as a result of plowing and erosion. Identifying sources and extent of disturbance has practical importance for archaeologists including assessing the accuracy of artifact proveniences, identifying areas to carry out more time consuming, less efficient geophysical survey, identifying areas to conduct more excavations, and whether the construction of new buildings or roads should be undertaken in a given area.