Arizona’s Agathla Peak

March 25, 2019

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Photographer: Ray Boren 
Summary Author: Ray Boren 

A prominent monolith jutting skyward just south of the famed sandstone buttes of Monument Valley Navajo Tribal Park, Agathla Peak, shown here in a photo taken on November 1, 2018, is the neck, or plug, of hardened magma, breccia and dikes of minette once at the heart of a now-extinct volcano that erupted 25 million to 30 million years ago. It's but one of about 80 landforms, and second in size only to New Mexico’s Shiprock, recognized as part of the Navajo Volcanic Field, that spreads across the Four Corners area where Arizona, Utah, New Mexico and Colorado meet on maps of the United States.

Agathla is an English variant of the Diné bizaad (or Navajo) name aghaałą́, meaning "much wool". The wool, in this case, was apparently the fur of pronghorn antelope and deer that was shed or accumulated on the rock, according to the U.S. Geological Survey’s Geographic Names Information System. It's also been known by the Spanish name El Capitan.

Soaring about 1,500 feet (457 m) above the surrounding landscape and nearby U.S. Highway 163, north of Kayenta, Ariz., Agathla Peak now tops out at 7,099 feet (2,164 m) above sea level. When it first surfaced eons ago, the volcano’s outlet, probably a maar, pierced what is now the Colorado Plateau. Since then erosion has removed vast amounts of the surrounding rock, mostly sandstone, revealing the harder and more resistant volcanic intrusion.

Photo Details: Camera: NIKON D3200; Exposure Time: 0.0020s (1/500); Aperture: ƒ/11.0; ISO equivalent: 400; Focal Length (35mm): 129.