faerygirl wrote:
The few things I have read (and maybe it just says a lot about the kind of books I opt for!) suggest its all part of Shaman rituals. If you take certain hallucinogens then you see concentric rings, squiggly lines, zigzags etc.
Oh and that whatisname... Narby, he did experiments with ayahuasca and saw giant snakes as well as recurring geometric patterns. I think these patterns became so important to the people as a connection to other dimentions that they were used at stone circles to help invoke the same spirits. These were (and still are in areas where there are still shamans) often believed to be the ACTUAL next dimention or the land of the dead or the spirits of wherever you were trying to get to.
When Graham Hancock took ibogaine as study for the book Supernatural he saw the exact symbols that are often seen as rock art in ancient caves such a wiggly lines, serpents and circles.