Termites and stone lines - traps for the unwary archaeologist

Abstract

An unproven assumption in the case of prehistoric archaeological sites has always been that where the optical and/or radiocarbon ages are in stratigraphic order, becoming older with depth, the ages obtained provide unambiguous ages for any artefacts within the same stratigraphic horizon. This is not necessarily so. A growing body of evidence gathered by dating practitioners, soil scientists and geomorphologists during the past few decades in many parts of the world has shown that post-depositional and syn-depositional disturbance is the norm rather than the exception.Field observations in tropical northern Australia show that termite activity operating in conjunction with soil creep, subsurface lateral eluviation and slope wash can generate a buried stone layer 30–50 cm thick within 10,000–15,000 years and can replenish the topsoil to a depth of 15–30 cm thick within the same time. Termites can cause differential displacement of artefacts and can seriously interfere with attempts to obtain a reliable chronology based on radiocarbon and/or optical ages for the sediments in which the artefacts occur.