There is clearly no registered archeological site because nobody registered it.

Just knowing something is there isn't enough to register a place as an archeological site, you have at least prove it has archeological value (usually done by visiting the place).

I have a place nearby where you can see Trilobites that went extinct 200 million years ago. And you can just take them and go, because historical value of them isn't that high and there is no registered site. It's a well known place, and archeological students sometimes even practice there.