Chaco Canyon's Pueblo Bonito and the "threatening rock"
"Threatening rock" [at center in photo, below right] had already begun to cleave from the canyon wall when the first dwellings were built in this location in around 850 CE, and the inhabitants attempted to shore it up with rocks wedged under the outward-facing bottom edges.
Pueblo Bonito had been abandoned for almost 700 years before the estimated 30,000-ton rock came down on the already-crumbling rooms in 1941.
From the midst of the rubble pile that was once threatening rock, looking towards the remaining ruins of Pueblo Bonito.
Aerial photo of Pueblo Bonito taken by Charles Lindbergh in 1929.
Pueblo Bonito, the largest "great house" in Chaco Canyon Culture Park in northwestern New Mexico, from the rim of the South Mesa.
A closer view showing the fragments of so-called "threatening rock", which fell onto the northeast corner of the structure in January 1941, destroying about 30 rooms.