3 PDFs at Turtle Island

And one, in part, says this: "Quartz shatter was sometimes placed along trails(Apple 2005: 107)so that those travelling the trails at night would be able to see the trail from the moonlight reflecting off of the quartz. Quartz piles along trails were noted during a site visit to the Mule Mountain Spring and related
earth figures site...Rock cairns, which variably mark trails, burials, or other phenomena, occur in the project vicinity as piles of rock standing from one to three courses in height.Older cairns are frequently indicated by stronger desert varnish or patina (Nixon et al. 2011)..."
http://wakinguponturtleisland.blogspot.com/2013/09/3-pdfs-about-cultural-landscape.html