The 1085 Eruption and the Wupatki Boom

Around ten eighty-five of the Common Era, a volcano erupted north of what is now Flagstaff. It was not brief. The eruption lasted months, possibly longer. When it was done, several hundred square miles of the Colorado Plateau were buried under a layer of volcanic cinder and ash. The trees were gone. The land was black. Anyone watching from a distance would have concluded that the region was finished.

They would have been wrong about this in an interesting way.

The cinder layer, it turned out, acted as a kind of agricultural mulch. In the high desert, where moisture evaporates quickly from exposed soil, the porous volcanic material absorbed rain and slowed its escape. Farmers who returned to test the land found that crops grew better in the cinder zone than they had before the eruption. Word spread across the regional trade network, which connected the Colorado Plateau to communities across the Southwest. Within a few decades, Wupatki Pueblo, northeast of Sunset Crater, had grown from a modest structure into one of the largest pueblos in the entire Southwest. At its peak, Wupatki had more than one hundred rooms and a population that likely reached into the hundreds. Trade goods from the Pacific coast and the Gulf of Mexico have been found in its ruins.

The growth was real, and it had an expiration date. By approximately twelve twenty-five of the Common Era, the region was in severe drought. The agricultural advantage of the cinder layer could not overcome a sustained failure of rainfall. The population dispersed. Wupatki was abandoned. The great pueblo stood empty.

What the archaeology records is something the human instinct does not easily accommodate: a catastrophe that created opportunity, followed by prosperity, followed by a departure driven by a different catastrophe entirely. The volcano was not the end. The drought was.