A giant crack has been widening on the Navajo Reservation near the small town of Leupp, Arizona. The crack occurs 12 miles north of Interstate 40 about half way between Flagstaff and Winslow.

The Navajo Post has a photograph and short video of the crack. Arizona State Geologist Lee Allison has two short posts on the crack here and here.  Photos and a geologic map are included in those posts.

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.

According to the Navajo Post, the crack has gotten so big that it had to be fenced in.

The photo below shows the crack just south of Leupp Road.

See also:

Earth Fissures in Arizona

Earthquake hazard near Flagstaff assessed, Video

Photos and video of Highway 89 slump near Page Arizona

Arizona Geologic History: Chapter 1, Precambrian Time When Arizona was at the South Pole

Arizona Geological History: Chapter 2, Cambrian and Ordovician Time

Arizona Geological History: Chapter 3: Devonian to Permian Time

Arizona Geological History Chapter 4: Triassic Period

Arizona Geological History Chapter 5: Jurassic Time

Arizona Geological History 6, The Cretaceous Period

Arizona Geological History 7: The Cenozoic Era

The Arizona Geological Survey has been busy mapping the many earth fissures in Arizona. Most earth fissures occur in the corridor between Tucson and Phoenix, and from Phoenix west along interstate 10 (see map below).

Earth fissures develop from soil compaction associated with extensive pumping of groundwater. The fissures range in width from a few inches to tens of feet. Length of the fissures ranges from hundreds of feet to miles.

These fissures pose danger to cattle, wildlife, and unwary humans. The presence or possibility of a fissure-prone area also has implications for municipal planners, developers, highways, and railroads. And, because they tend to develop perpendicular to surface drainage, they can capture runoff and develop into large gullies.

The gateway to the Survey’s many maps and reports is the Earth Fissure Viewer, an interactive map that allows you to zoom in on areas and get detailed maps. Maps, reports, and photos are also available at the Survey’s Earth Fissure Center.