Magnetic prospection

Magnetometery is most suitable to map all kinds of archaeological structures causing anomalies in the Earth's magnetic field across large, open, unobstructed areas, such as prehistoric pits, trenches, postholes, walls, fire places and kilns. Magnetometer surveys result in a single data value per surface point without direct information about the depth of the buried structures.

The most important issues regarding professional archaeological prospection are speed, sensitivity and spatial resolution. The coverage of considerably larger areas and increased sample densities at constant expenditure of time in the field are today possible by high inherent sample rates of the used instruments, by higher survey speed through the use of motorized, multichannel survey systems and advanced navigation solutions. The use of motorized measurement devices for archaeological prospection implicates several technological and methodological challenges.

State-of-the-art fluxgate gradiometer (FG) and very sensitive Caesium (CS) magnetometer systems are operated on purpose-built non-magnetic carts towed by motorized All Terrain Vehicles (ATV) or Quad bikes. The ATVs carry the power supply, the data logging unit and advanced navigation systems. Multiple sensor arrangements with up to 10 FG probes mounted with 25 cm cross-line spacing on the trailers, as well as access to more than a dozen CS sensors permits the setup of several magnetometer arrays for efficient large-scale magnetic surveys.