Well, here's a shift from the climate change articles I've been reading, which I kind of need to do....... I love petroglyphs, and in the southwest there are plenty of sites where Anasazi, Hohokum, and Pueblo petroglyphs can be seen.
One phenomenon I've always found interesting is the "solarized shaman" petroglyph, an image that can be found throughout the world. I've also run across UFO researchers who claim that these images depict aliens or people in space helmets, but it's much more likely that they represent shamans who have entered the ecstatic visionary state in order to commune with their spirit helpers, and also while under the influence of sacred herbs that altar consciousness, such as peyote.
They represent the "halos" that ancient indigenous people no doubt observed around highly energized people, shamans and healers, who were in contact with the spirit world. Just as we can observe energy fields around people, plants, and even objects with Kirilian photography, so did they.