So, after reading the link, if you find a coin from 1950, your screwed? Do these acts also cover private property? What if you find a miniball dating from the civil war? That most certainly is over 100 years old, is historical, and could be called an archaeological site. Right?
Well there was no civil war fought here so who's to say just how old a chunk of lead you happen to find is? Could be a shotgun slug or a modern muzzle loader ball.
What went on in northern lower Michigan where these forests are is the logging industry and that's about it. The buildings are long gone and the RR tracks were taken up 80 years before I was born.
Check your local national forests for historical areas before hunting it, but around here man there really isn't much besides water and trees.