Arizona's mysterious clock of ancient times
Like clockwork, a recently discovered Arizona rock art calendar marks the passing of the seasons
By Larry Bleiberg
17 May 2018
All day the sun had been hiding behind clouds, but Kenneth Zoll wasnt worried.
Standing in front of panels of rock art carved nearly a millennium ago, the researcher pointed to petroglyphs of snakes, coyote and deer, and singled out several concentric circles. Then he told his 100-strong audience to note the two rocks wedged into a crack above his head.
Zoll swept his arm across the entire scene. This, he explained, was a way to track time.
As if by command, a few minutes later the clouds began to part. And at 13:40, like a perfectly calibrated Swiss watch, a beam of light passed over the rocks and projected two shadows across the panel. For the next six minutes, their edge held still, just touching three circles.
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