Thank you for this - first because I'm fascinated by your process - Hill Marks piqued my interest even though I haven't had a chance to utilize it much yet. But also because it opened my eyes to some fascinating things of which I wasn't aware, like the Schuylkill notes (I'm originally from PA and very familiar with the area where this is apparently happening). I'm immediately reminded of the Toynbee tiles, which have sort of faded from public consciousness as they've disappeared from the streets.