ok, so im sorta speaking out of my but here because i know nothing about how to do this
...yesterday i was watching some treasure hunters on tv look for jesse james hidden treasure cache, they were using a compass at at certian areas it would deviate from north by up to 30 degree. then when they hit that area with ground penetrating radar they found anamolies under the ground that may or may not be a cache. does anyone know how the compass deviates like that or how a site that better describes this sort of compass technique?
Etrac, Fisher CZ7A pro, Modded Excal 1000, Best finds to date:1793 flowing hair, three civil war plates, 12g 18K ring ;) keep on digging!B.R.A.V.O.