Magnetics

Method: When a ferrous material is placed within a magnetic field such as the earth's, it develops an induced magnetic field. The induced field is superimposed on the earth's field at that location, creating a magnetic anomaly.

In the gradient method, the total field is measured simultaneously at two elevations by using two sensors on a staff separated by a fixed distance. The difference in magnetic intensity between the two sensors divided by the distance between them is the vertical gradient. This technique reduces interference from solar magnetic storms and regional magnetic changes. This technique is particularly useful for locating small, shallow objects and is also useful for estimating burial depth of objects. The results of magnetometer surveys are presented to the client in a full report that generally includes magnetic profiles, and an index map showing locations of magnetic anomalies. Magnetic contour maps and other graphic presentations are also available.