Well that trail used to be a road way back then. Is that ring as big as a nickle or will it fit on your finger? I'm wondering how old it might be - it looks like it may have been silver plated brass? With the Cibola what you need to do is put the discrimination on the "I" in foil and when you get a signal, thumb the disc level up until it starts to cut out - make a note of where that is and then dig the target. WIth that method you should be able to tell what signals are gun casings, chunks of lead, and even coins. Did you find anything else out at that spot today?
Ian