So last month I'm with my buddies in an open space park in Boulder. They have long abandoned coal mines, some of which have been on fire for 50-100+ years underground. We find the old entrance of one of the Lewis mines, which is now just a sort of ditch thing, and walk down in there. There aren't any signs, nothing. In the ditch is a visible vein of coal, just a few inches high. We proceed to look at little pieces of it, removing them from the vein. Then there are some fossilized shells and stuff, not particularly recognizable or of any quality, but they look neat so we pick them up and examine them. After a while of doing this, we start to leave. No sooner are we at the top of the ridge than a ranger stands up, who apparently was hiding there for a while.
A month later now, we're picking up the sides of the roads near open space parks for trash, with 40 hours of community service to complete and $160 in court fees. Luckily we got a deferred something so the misdemeanor charge will go off the records in a year, as long as none of us get caught doing something similar. Whatever that would be.
It should also be noted that, well at least I've heard, it's legal in most of Colorado to pick up little fossils and stuff in parks like this. They aren't of any real value, and, well it's a coal mine!
I'm not sure what lesson I've learned from this experience other than to avoid Boulder.
Here's the Boulder open space rules if you're interested: http://www.co.boulder.co.us/openspace/recreating/public_parks/parks_pdfs/rules®s2005_50.pdf