Hey Cas, I had not heard that before. It would make sense though. I have heard that the last official marking was of course an X or some form of one. Maybe crossed pick heads?
I have been hunting in a very worked area. I don't expect to find any gold, but am learning how they marked things and used those marks. I cant afford all the treasure hunting books out there. lol. unfortunately, a lot of trails are destroyed. But I still find stuff.