I would recommend:
1) look at the trees. The locals used different trees to demarcate areas in the day. Osage orange for instance was popular around cemeteries. Also, are trees in a conspicuous line in some area? Probably marked a boundary of a yard or property. The biggest trees are the oldest and best for climbing, and stuff falling out of pockets.
2) look for glass. You found a couple old pop bottles, that's a sign that goes up through about mid 1980s if my memory serves. It might be ok to hunt, but might not. Look for more glass on the surface because it tends not to sink into the earth as fast as metals do. Old greenish hue or light blue hue glass, square shapes are common, is usually the older stuff. If you find the glass, metal is likely hiding underneath.
3) look for foundations. I have found some really really old foundations in my work. They don't disappear too quick, and even after no visible signs of the structure are there, the level flat area where a foundation sat still is easy to distinguish.
4) get upslope. Not only are floods possible, they are probable, and not only do they wash things away, but they deposit them too. Get permission and dig a deep 3'-4' hole to see what the soil profile looks like. Are there multiple layers? See any thin bands laid by individual floods? How deep are they? Read up on geoarchaeology to learn more. The good stuff might be hiding under a foot or more of deposited sediments, out of your detectors range. If that is the case, get a detector that can use a 15" WOT coil and you might have more depth and luck. If you don't have the $$$, focus on areas upslope slightly where sediments are not as thick.
Cheers
Fishermanjuice
