Sweep widths and the detection of artifacts in archaeological survey

In many parts of the world, one of the principal means for discovering archaeological resources is terrestrial archaeological survey for small scatters of generally unobtrusive artifacts on the surface. Yet archaeologists have expended relatively little research on the factors that affect detection of such artifacts or the impacts they have on the reliability of surveys. We employ mock survey of plowed fields ‘seeded’ with a variety of artifacts in order to evaluate the effectiveness of pedestrian survey (fieldwalking) with respect to search time and transect spacing. Our results confirm theoretical expectations about the diminishing returns on increases of search effort, while also demonstrating variation in ‘sweep widths’ for different artifact types and surveyor speed and the effects of walking toward or away from the sun. Preliminary results have implications for the most efficient spacing of survey transects as well as the evaluation of completed surveys, since some artifact types have extremely low probabilities of detection even at high densities of search effort.