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. Nearby Hunt's Hole lies several miles just south of Kilbourne Hole. These holes are rare examples of volcanic action without a mountainous rim. The theory of formation is that a volcanic eruption occurs in the presence of groundwater, beneath the surface of the earth. As the magma encounters the groundwater, explosive interactions occur. 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. The crater is thought to be 80,000 years old.[1][2]
The volcanic features around El Paso and vicinity are part of the Rio Grande rift, which extends northward into Colorado.
[edit] Description of the crater
- Latitude/Longitude: 31°58′19″N 106°57′53″W / 31.97194°N 106.96472°WCoordinates: 31°58′19″N 106°57′53″W / 31.97194°N 106.96472°W
- Elevation: 4,239 feet (1,292 m)
- Crater diameter: 1.5x2.1 miles (2.4x3.4 km)
- Depth: 443 feet (135 m)
The hole is over a mile wide, and over 300 feet (91 m) deep. Two basalt cliffs inside the crater, with the characteristic reddish purple hexagonal columns, occupy the northeast and southeast sides of the crater. The cliffs are about 40 feet (12 m) high. Layers of ashfall and crumbling sediment also rise about 40 feet (12 m) high, on the south rim of the crater. This ashfall section will not support your weight, on the south rim; it is safer to stay on the basalt cliffs and the sand dunes. Sand dunes have collected on the east side of the crater, rising about 100 feet (30 m) above the desert floor. A dry lakebed lies on the floor of the crater.
The basalt cliffs resemble the cliffs of the Devils Postpile National Monument near Yosemite National Park, except that they are not as tall.
Green peridot crystals occur in the lava.
Lava chunks exist in abundance. The basalt column fragments are each larger than a person.
Apollo astronauts trained in these craters in 1969.[3][4]
[edit] Notes
- ^ pp. 273-281, Cordell, L. (1975) "Combined geophysical studies at Kilbourne Hole maar", New Mexico, New Mexico Geological Society Guidebook, 26th Field Conference, as recorded in:
- ^ p. 310, Charles A. Wood and Jürgen Kienle, eds. (1990) Volcanoes of North America: United States and Canada. Cambridge ISBN 0-521-36469-8
- ^ http://www.desertusa.com/mag06/apr/volcanoes.html Kilbourne Hole: Apollo training site
- ^ http://history.nasa.gov/alsj/ap-geotrips.pdf Geology field exercises for Apollo missions. p.8
[edit] External links
UTEP Potrillo Maar Experiment http://www.geo.utep.edu/pub/miller/pvfweb/ Satellite view of El Paso region, including Kilbourne Hole, illustrates The Potrillo Volcanic Field Seismic Experiment
