The aim of a magnetic survey is to investigate subsurface geology on the basis of the anomalies in the
earth’s magnetic field resulting from the magnetic properties of the underlying rocks.  In general, the magnetic content (susceptibility) of rocks is extremely variable depending on the type of rock and the environment it is in. Common causes of magnetic anomalies include dykes, faults and lava flows. This method can be used in finding buried steel tanks and waste drums, detecting iron and steel obstructions, locating unmarked mineshafts, accurately mapping archaeological features, mapping basic igneous intrusives & faults, an evaluating the size and shape of ore bodies.