Sun Daggers
The Anasazi lived in the desert country in New Mexico, Colorado, Utah and Arizona about 900 years ago
They created an observatory in a high rock that rises from the canyon floor
3 large slabs of rock are leaning against the vertical face of the butte mountain
2 spirals have been cut into the rock behind them. At noon on the summer solstice, a tiny shaft of light falls between the 2 slabs, making a spot that looks like a dagger right into the middle of the larger spiral
As the weeks progress, the dagger of sunlight moves to the right, with a second one appearing, moving as the days progress to winter