Went over the same area with my wife's detector, a White's Prism 6T. The soil conditions are a very hard packed clay for 50% of the area and easy digging dirt in the other. This is also right next to the overhead power lines. I maxed out with the Ace 250 at about 5-1/2 inch depth. Now I pealed down to another layer with the 6T getting 6-7 inch depth. The deeper the fewer so I only rescued three Wheaties, 1936, 1935 and a 1912. I plan to go back to see if anything else can show up. Makes for a nice experiment.