Kilbourne Hole

Kilbourne Hole is a maar volcanic crater, located 30 miles (48 km) west of the Franklin Mountains of El Paso, Texas, in the Potrillo volcanic field of Doña Ana County, New Mexico. Another maar, Hunt's Hole, lies just two miles south of Kilbourne Hole. These holes are rare examples of volcanic action without a mountainous rim.

Kilbourne Hole (center) and Hunt's Hole (lower right), with White Sands National Park lit by the sun in the distance beyond the Organ Mountains.
Basalt cliffs of Kilbourne Hole, looking northwest from near the southwest corner. The cliffs come from the earlier Cenozoic Afton basalt flow; the magma that caused the maar explosion was also basalt.[1]

The theory of maar formation is that rising magma super-heats water-saturated earth, far enough below the surface that a high pressure can be contained. At some point, the pressure is too much, and a steam explosion occurs, throwing the earth out in a catastrophic event.[2] Country rocks are fragmented and expelled in the atmosphere (together with fragments of the magma), eventually creating a deep crater, the bottom of which sits below the pre-eruptive ground surface.

Estimates of the age of the crater vary from about 24,000 to about 80,000 years.[3][1][4]

The volcanic features around El Paso and vicinity are part of the Potrillo volcanic field, in the Rio Grande rift, which extends northward into Colorado.

In 1975, Kilbourne Hole was designated as a National Natural Landmark by the National Park Service.[5]

Description of the crater
A view of the Kilbourne Hole from the trail at the southwest corner. Everything visible in this photo is the maar, bottom lands and rim with basalt cliffs.

The crater is at an elevation of 4,239 ft (1,292 m). It has a diameter of 1.5 mi (2.4 km) by 2.1 mi (3.4 km) and a depth of 443 ft (135 m).[6]

The hole is over a mile wide, and over 300 feet (91 m) deep, with crumbling basalt cliffs all around except at the southwest corner. The basalt cliffs resemble the cliffs of the Devils Postpile National Monument near Yosemite National Park, with the characteristic reddish purple hexagonal columns, except that they are not as tall. The cliffs are about 40 feet (12 m) high. Lava chunks exist in abundance.

Hunt's Hole is a little smaller, with basalt cliffs only at the northeast and southeast sides of the crater. Layers of ashfall and crumbling sediment also rise about 40 feet (12 m) high, on the south rim of the crater. Sand dunes have collected on the east sides of the both craters, rising about 100 feet (30 m) above the desert floor. A dry lakebed lies on the floor of each crater.

NASA training

NASA geologically trained the Apollo Astronauts in April and Nov. 1969, June 1970, and Jan. and Dec. 1971. Astronauts who would use this training on the Moon included Apollo 12's Pete Conrad and Alan Bean, Apollo 14's Alan Shepard and Edgar Mitchell, Apollo 15's David Scott and James Irwin, Apollo 16's John Young and Charlie Duke, and Apollo 17's Gene Cernan and Jack Schmitt.[7]

General location of Kilbourne Hole, Doña Ana County, New Mexico

Access

Kilbourne Hole is in BLM land and is available as an unimproved recreational area.[8] It is accessed via Doña Ana County Road A-011, driving 8 miles west from the railroad. The hole is "on the right, past the big tan dirt bank."[8] Much of the land inside the hole is private property. Hunt's Hole is about 2 miles south on A-013.

BLM sign on the road to Kilbourne Hole.

References
  1. Wood, Charles A.; Kienle, Jürgen (eds.) (1990). Volcanoes of North America: United States and Canada. Cambridge University Press. pp. 310–311. ISBN 0-521-36469-8.CS1 maint: extra text: authors list (link)
  2. "Fossils/Kilbourne Hole". Desert Diary. UTEP Geology Dept. Archived from the original on 2010-06-14. Retrieved 4 Aug 2012.
  3. Cordell, L. (1975). "Combined Geophysical Studies at Kilbourne Hole Maar". New Mexico Geological Society Guidebook: 26th Field Conference. University of New Mexico Press: 273–281.
  4. Leland H. Gile (1987). "A Pedogenic Chronology for Kilbourne Hole, Southern New Mexico: II. Time of the Explosions and Soil Events Before the Explosions". Soil Science Society of America Journal. 51 (3): 752–760. doi:10.2136/sssaj1987.03615995005100030033x.
  5. "National Natural Landmarks - National Natural Landmarks (U.S. National Park Service)". www.nps.gov. Retrieved 2019-03-25. Year designated: 1975
  6. 2016 National Land Cover (NLCD) dataset Kilbourne Hole
  7. Phinney, William (2015). Science Training History of the Apollo Astronauts. NASA SP -2015-626. pp. 233, 235, 237, 241, 245, 251.
  8. "Kilbourne Hole Volcanic Crater". Retrieved 30 July 2012.

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