Enormous Crack Opens On Navajo Reservation

Birds fly and grabens grow:

The crack is along an extensional fault system mapped in 1984 by George Billingsley of the U.S. Geological Survey. Movement on the fault may be related to the numerous small earthquakes in the area (see Arizona is earthquake country) that derive from crustal extension. The 900-foot long crack is parallel to joints in the Kaibab Limestone.