I am the world's biggest skeptic - but - on a visit some years ago to the National Tramway Museum, Crich, Derbyshire, I was once given the opportunity to 'dowse'.
There's a guy there (a tram mechanic, I think) who operates from a wooden hut on the edge of a Car Park. The Car Park has an asphalt surface with no distinguishing marks, no wear marks - just plain asphalt.
On request, he'll hand you a pair of L-shaped brazing rods, and show you how to hold them, inside thin-bore tubes, so that the rods are free to rotate, without any influence from the hand's muscles. He'll ask you to walk around the Car Park, and note what happens. While you're doing this, he'll stay in his shed so as not to influence your behaviour in any way.
As I walked across the Car Park, the rods suddenly crossed over, and as I walked backwards, they uncrossed. It didn't take long to establish that there was a line of 'something' running across the Car Park, the direction of which I'll not reveal in case somebody from this forum wants to try this for themselves, at that location.
On return to the shed, the guy will ask you what you discovered, and will then show you a geological map of the area, in which a vein of Lead Ore runs exactly where the rods responded.
It is a truly uncanny experience, and defies explanation - other than the possibility of an aerial electrostatic charge perhaps being grounded by the Lead Ore - that's the only tentative explanation I can offer.
Near-Earth atmospheric electrostatic potentials are well known of course, and I suspect bees probably use them for navigation, as their eyesight is - contrary to popular opinion - rubbish. Whereas their ability to detect electrostatic fields has been established for some time, although for some strange reason is constantly overlooked by researchers.
LJ