Fajada Butte stands alone at the mouth of Chaco Canyon, a banded tower rising more than three hundred feet from the valley floor. Near its summit, on a narrow ledge, three slabs of sandstone lean against the cliff, and behind them two spirals are pecked into the rock.
June 1977
In 1977 Anna Sofaer, an artist volunteering on a survey of Chaco's rock art, climbed to the ledge near midday about a week before the summer solstice and found a narrow blade of sunlight cutting down through the larger spiral. She called it the Sun Dagger. With colleagues she spent years recording what the slabs did with the light. At the summer solstice a single dagger crossed the larger spiral through its center; at the winter solstice two daggers framed it on either side; at the equinoxes a dagger crossed the smaller spiral. The team later argued that shadows from the rising moon marked the two extremes of its 18.6-year cycle on the larger spiral as well.
The argument
The solar markings are widely accepted. The lunar ones are argued over, and so is how much was planned: critics have asked how likely it is that light and shadow would fall on some carving at some significant date by chance, and some have wondered whether the slabs were set there or fell naturally and were put to use. Nobody disputes that the people of Chaco watched the sky closely. Their great houses and kivas were laid out on the cardinal directions and on the paths of the sun and moon.
1989
The ledge could not take the attention. The Park Service restricted access to the butte in 1982. At the summer solstice of 1989 rangers found that two of the slabs had shifted, apparently because erosion sped up by visitors' feet had undercut them, and the dagger no longer passed through the center of the spiral. Since then the butte has been closed to everyone except people monitoring the site.
Whose calendar
The Hopi and the Pueblos of the Rio Grande count the people of Chaco among their ancestors, and Fajada and the canyon's other sites are part of their histories. In Pueblo communities, people charged with watching the sun have long tracked its rising against points on the horizon to time planting and ceremonies, which makes the spiral on the butte less a mystery than a relative.
From the road into Chaco Culture National Historical Park, Fajada rises at the canyon's entrance. The ledge itself is seen now only in photographs.