Beneath the Desert Soil – Archaeological Prospecting with a Caesium Magnetometer

Abstract

Large area prospection with highly sensitive caesium magnetometers up to now has been one of the most successful geophysical prospecting methods in archaeology. The application of this method on pre-Hispanic cultures provides a perfect framework and has a high potential capacity for further development of magnetometry and archaeological prospection methods in general. Both shallow inclination as well as the low intensity of the geomagnetic field near the equator requires an adaption and modification of the caesium magnetometer. In the case of the geoglyphs of the Peruvian Atacama desert – a UNESCO World Heritage site since 1994 – the prospecting results are exemplified in detail. Magnetometry enables us to visualise not only the traces of numerous lightning strikes in the desert but also the traces of thus far unknown archaeological structures and older invisible lines beneath the multiphase trapezoidal geoglyphs. Magnetometry therefore turns from pure geophysics to a perfect archaeological tool for studying ancient sites without destruction.