Yesterday, I spent the morning with some friends at the V Bar V Heritage site near the Verde Valley, about an hour from home, and saw some spectacular petroglyphs. These petroglyphs were made by the Sinaguan people in what has been termed the Beaver Creek Rock Art style (dating from about 1100 AD). What was fascinating to me was that they have discovered sunbeams hitting certain parts of a stair-step type design on certain days of the years, which experts believe are signs of when planting should occur. There is also a small area that has been carved out that casts a shadow resembling the San Francisco peaks, a sacred site to local native populations.
If you look closely at the upper right part of the photo above, you can see the stair step (zigzag) glyph, each step of which is lit by sunbeams on a specific day during the growing season. Early calendar!