....As to the storms coming ashore,changing everything BIG TIME,sand bottom wise.......I bet the time frame of finds in Lake Michigan Has no rhyme nor reason,as much as these windy storms dredge up the bottom here.....Can Probly find 100+ years old silver and old jewelry,and new clad may be buried 2-3 feet or more deep,,and the GOOD gold items,who knows??The beach bottoms from shallow out to 4-5 feet deep are CONSTANTLY CHANGING......Just think of them 'treasure coast' beaches in Florida,how much from them wrecks is NEVER FOUND,because of hurricane activity over,what,300-400 years........Same as Lake Michigan,YOWSA.....