Colorado stone structures

Bruce McAleer sent this:

Here's a google link. Pages 9, 10 and 11 (I haven't read further yet) have photos and archaeological reporting on stone enclosures called "vision quest sites" in proximity to rock shelters with rock art. Also mention of cairns and walls and a few mis-assumptions about their likely being colonial. Worth a look when you get time.

http://www.coloradohistory-oahp.org/programareas/paac/CASpaper.pdf