My point is that there could be sites identified on that property, but you wouldn't know it, and they wouldn't know what you were up to. Information on the location of designated archaeological sites isn't easy to come by. Guess why.....
Re.: the trinomial archie system of designating a site : You're right that : If you are armed with a system #, and simply go to plug it into google : You're right : A lot of times you're
NOT going to come up with any "x-marks-the-spot" . Because as you hint : Those are white-glove credentialed archive material. Except, of course, when the spot is "no secret". Eg.: Obvious sensitive tourist historic monuments, battlegrounds, etc....
But let's just "cut to the chase" : To the extent that what you are saying might be true that : "... We can't be 100% certain we're not walking on top of a spot that's designated in the archie archives with their numbering system" : If the day ever-came that this remote possibility was to affect our choice of spots-to-detect, is the day we all might as well sit at home and take up needle-point. Because, like anything , we can "worry ourselves to death" with "
what if's" . Yet a quick look at forum show & tells, show that oodles of us are finding cool things in public forests, beaches, deserts, etc.... Apparently they didn't think-through-the-logistics of the "what if's"?
If a spot was A) in the middle of nowhere, and B) granted one of those #'s, and C) yet is a secret to all-but-the-few-lone archies who .... 30 yrs. ago .... submitted the site to receive a #, then ..... Let's be frank : THOSE are going to be the sorts of sites that probably no-one-alive, that you'd ever happen-to-run into, is likewise going to know about it either.
I've tracked and studied several site #'s. Because we've found the archie # in conjunction with buttons or coins found. Yet when we try to reverse-engineer it, to get an "x-marks-the-spot", the trail sometimes grows cold. But there is a way to "crack" that: The repository of the libraries that hold those archie-study-applications, are housed at various designated universities in each state. And to gain access to those store rooms (rooms filled with boring file-cabinets and boxes), you merely need to have 'credentials'. And getting credentials isn't that hard. I can make an entire post about this, but won't take up space here for that.
But I'm just going into this to make a point: Whenever we have "cracked" those #'s, and hit the sites, there is NO WAY IN HECK that anyone, who would happen-chance-be passing-us-by, is or was any wiser than we were, before we cracked the nut.
Not saying to "throw caution to the wind". OF COURSE don't be snooping around sensitive things which are a no-brainer that they are known-sites to passerbys.
And not sure about other states, but most all of the trinomial #'s in CA are pre-European contact Indian related. Eg.: midden sites, or bone-sites. They get the # & their dusty folder goes in the archives, and odds are .... no one has set foot there in the last 20, 30, or 40 yrs. And aside from the singular archie who sent in the application, I'll bet you'd be hard-pressed to find anyone else on earth that even knows about it. Barring, as I say, noted obvious sensitive monuments (obvious structures, battle-sites, ghost-towns, etc....)