Emory Cauldron, Black Range, New Mexico, source of the Kneeling Nun Tuff
— Wolfgang E. Elston, William R. Seager, and Russell E. Clemons

The Kneeling Nun Tuff, an ash-flow tuff (ignimbrite) of Oligocene age (33.4 ± 1.0 m.y.; McDowell, 1971), is best known for its exposures in the Santa Rita mining district. Its source is a large resurgent cauldron in the southern part of the Black Range in Sierra and Grant Counties, for which we pro-pose the name Emory cauldron. It is one of the largest and best-exposed cauldrons yet described in North America. The central resurgent uplift, which nearly fills the cauldron, measures about 55 by 25 km, and is elongate parallel to the northerly trend of the Black Range. Peripheral fractures invaded by rhyolite domes extend outward for another 25 km from the cauldron margin. The outflow sheet of Kneeling Nun Tuff extends at least 30 km beyond the cauldron margin; its original extent is unknown and was probably much greater. Many of the faults associated with the cauldron were reactivated during a post-cauldron episode of Basin and Range faulting, which caused structural relief to be exaggerated. Deeper parts of the cauldron were subsequently exposed by dissection.

 

The southern part of the Emory cauldron is unusually well exposed and is accessible by many roads, including State Highway 90, a paved road. The northern part lies in the Black Range Primitive area and is poorly known and difficult to reach. This preliminary report deals mainly with the southern part.

 

The Emory cauldron is named after Emory Pass in sec. 15, T. 16 S., R. 9 W., which in turn was named after Lt. W. H. Emory, U.S. Army, who commanded a force that crossed the Black Range in 1846.