In electromagnetic dip-angle (tilt-angle) profiling surveys, the frequency used controls the effective skin depth (depth of investigation): higher frequencies have shallower skin depths (more rapid signal attenuation with depth) while lower frequencies penetrate to greater depths; a zero crossover in the dip-angle response marks the horizontal position of a subsurface conductor, and if the same crossover location is observed consistently across multiple parallel profiles, this indicates the conductor has a strike length and orientation consistent with intersecting all of those profiles at that position.