Metal detectors don’t for work much deeper than a meter, and less if there are more minerals in the rock/soil. Smell lingers, so dogs may be able to smell people if they’ve been there hours before and if there’s a small opening the scent can penetrate a collapsed section.
Metal detectors don’t for work much deeper than a meter, and less if there are more minerals in the rock/soil. Smell lingers, so dogs may be able to smell people if they’ve been there hours before and if there’s a small opening the scent can penetrate a collapsed section.