Interesting. I have dowsed for almost everything imaginable at one time or another. On topographical maps, I use a pendulum, depending on what the object(s) I am dowsing for determines which pendulum I use. Each one I have has its own definitive signature and ability. Most of the time I start with my master pendulum and then try to focus on a subtle hint as to what I have encountered. Then switching to a specialized pendulum to further determine the signature of the object. On your maps(google) or aerial, I normally use a pencil or my finger to get an overall feel for the region then try to decide on a specific target. On your last 2 maps there are multiple targets which tells me this area is heavily mineralized. Looks like an ancient volcanic eruption site. Red's methods are similar to mine in some respect as I learned mine from a professional treasure hunter and own several of his products, pendulums, L rods, and direction finders. Some use the bait method, others use a different concept, but all can be used by either method. Good luck. rockhound