Since rocks are more compact than soil, making them more magnetic, the magnetometer can detect the walls of long forgotten cities now buried. Certain ore deposits are readily found with this instrument. It is the basis of the military mine detector. The magnetometer is currently being used to detect buried drums which may contain hazardous waste materials. Because these drums are made of steel, they have magnetic properties to which the magnetometer is sensitive.
Magnetometers measure magnetism in units called gammas.
In Maine, the earth's magnetic field is normally 55,000 gammas. When this number is discounted, any change in magnetometer readings is due to local effects, that is, objects or formations which have magnetic characteristics. Have students trace and mark a three-inch grid on the surface of the filler. Use toothpicks to mark the grid points. See line and station sequence on student sheets.