Ok i have a question for you cache hunters out there. If a cache of coins are buried in a mason jar, could the lid erode and the jar its self sink further down in the soil?
I have never heard that before. I think you just found a lid. If you keep sweeping near and around that area and get a Beep... Keep digging. Or juice up the sensitivity and sweep away!
I have found many lids without jars. If there are coins there your detector should pick them up. Jars don't sink in the ground. They are at the same depth at which they were buried. You got to watch out for those old 'wives tales'.
I have found many lids. Only found one lid that was attached to a complete jar, & that got my heart pumping until I could dig the whole jar out only to see it was empty. The nerve of those people !