= Solution
Measure total <magnetic field> along the same south–north line with a calibrated <magnetometer>, recording position, time and sensor height. A simultaneous <base-station magnetometer> measures temporal variation so that diurnal changes can be removed from the moving survey. Avoid disturbed periods and magnetic contamination from vehicles, fences, power lines and equipment. Choose station spacing much smaller than the expected anomaly width, for example tens to hundreds of metres for a kilometre-scale target.
Subtract the epoch-appropriate <International Geomagnetic Reference Field> or another stated regional main-field model to obtain a <total-field magnetic anomaly>. Level overlapping traverses and remove offsets or drift where appropriate. Accurate terrain/sensor geometry is needed for comparison with a geological model, but there is no universal magnetic analogue of a constant-density <Bouguer slab> correction: the effect depends on the distribution and direction of <magnetization>. Measure <magnetic susceptibility> and <remanent magnetization> on representative <greenstones>, <granite> and host rock to test the assumed magnetic sources.
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