Question for you: did he cite for you the law or rule that said, what he's saying? Or is he merely just saying this because you asked him "can I metal detect?"
The reason I ask this, is that it's quite common for there to be no actual rule written anywhere, but if you ask, you can be told "no". In which case they would probably just morph something else to apply to you (like as in this case apparently, where they pull down cultural heritage or whatever, to fit your question).
Assuming there was no specific prohibition, and you merely got a "no" because you asked, here's another way to go about it in the future: Do not ask, if there's not already some specific prohibition. Look it up for yourself (park and school rules usualy available on-line at city hall websites). If it is silent on the issue, then so be it. Because odds are, no one cares or would ever have noticed. But since you ask, they say "no". Afterall, maybe they have images of geeks with shovels or whatever.
This begs the question: "but what if they morph clauses like 'disturbing the vegetation' or 'cultural heritage' or 'lost and found' or 'collecting" prohibitions', to apply to us? Shouldn't we therefore ask first?" If you start down that line of reasoning, I can gaurantee you that you will get a no at every single public place, everywhere. Because think of it: Is there ANY place you can go, and ask them this question:
"Hi, can go destruct your park, collect city-owned and other people's valuables for my own enjoyment, and steal and collect the past?" Do you think you can get a "yes"? And if you DID get a "yes" to your asking permission, it merely means you did not ask with the right set of mental pictures in their mind. If they said "yes", and you followed it up by "ok great, you mean I can dig then?" what do you think they would say? And even if they said "yes, as long as you cover it up", what if you then said "ok great, please sign this search and salvage permission agreement" What do you think they would say? And if they signed your search and salvage agreement, you ask "ok great, now I can collect coins and sell them on ebay for my own profit, right?" what do you think they would say?
and on and on it goes. Therefore I do not ask permission, for any place where it is not specifically disallowed, to begin with (by actual terminology citing "metal detecting specifically). If someone has an issue, they're welcome to tell me. But oddly, you will find that ...... as long as you're not being some sort of sore thumb or nuisance, that you will usually not be bothered, and people will pay you no mind. But oddly, in those same places where you could detect till you're blue in the face w/o anyone caring, you can still get a "no", if you ask.
Your desk-bound bureaucrat cites "historic resources" type stuff. But think of it, is there ANY park's director, ANYWHERE in the USA, that would say "my park has no historical resources"? I mean, do you think they're going to differentiate and say "well, this park is only built in the 1960s, so you can hunt there. But that park over there was built in the 1940s, so you can't hunt there", etc.... Of COURSE NOT. They will simply say "no to all" to make things easier. And is that to say they'd ever have given thought to the matter till you asked? Probably not.
