Ice Addict,
These coins were all 4 to 6 inches deep. Your XLT is a good machine for finding silver. I'm sure that if you walked over these coins, your XLT would have found them. I don't know what part of New York you live in, but I know there is a real good White's dealer in Albany. He should be able to give you some tips for finding silver in the Catskill and Adorondak areas. I believe there is a good MD club there too. Check them out. Good luck.
Bob