Ah, metal detecting, a favorite pastime for beach combers and airport security guards. We use a portable metal detector to find metal artifacts during project area surveys. Each “mag hit” is flagged, numbered, and mapped. Artifacts recovered are labeled with the corresponding location.
The sensitivity of a metal detector can be adjusted to find objects of a certain material or at a certain depth. A tone sounds when metal is detected. The pitch of the tone indicates what kind of metal it is. With practice, a metal 'detective' can learn to discern the differing tones and bypass modern trash. While the accuracy isn’t 100%, it is an additional tool in our arsenal to help us learn all we can about a site.