Uinkaret volcanic field

The Uinkaret volcanic field is an area of monogenetic volcanoes in northwestern Arizona, United States, located on the north rim of the Grand Canyon.[2]

Uinkaret volcanic field
Highest point
Elevation1,555 m (5,102 ft)[1]
Coordinates36°23′N 113°08′W
Geography
LocationMohave County, Arizona, US
Topo mapUSGS Mount Logan
Geology
Age of rock1.2 million years[2]
Mountain typevolcanic field
Last eruption1100 ± 75 years
Basalts from the Uinkaret volcanic field flow into the Grand Canyon from its North Rim. On the right is Lava Falls, with Vulcan's Throne at the top, just above the brightly lit cliff face at top center. Vulcan's Throne is about 73,000 years old.[1] These are among the most recent features of the Grand Canyon. The topmost layers over which the lava flowed, the Kaibab Limestone, was deposited in Early Permian time, around 290 million years ago.
Vulcan's Throne (top right) and Lava Falls, 2008 aerial photo

Lava flows from the Uinkaret volcanic field that have cascaded down into the Grand Canyon, damming the Colorado River, have been used to date the canyon's carving.[3] One of these cascades is today's Lava Falls. Lava Falls Rapid, below Lava Falls on the Colorado River, is "at all water levels, the most severe rapid in Grand Canyon."[4]

The Colorado River was dammed by lava flows multiple times from 725,000 to 100,000 years ago.[5] While some believe that these lava dams were stable, lasting up to 20,000 years and forming large reservoirs,[6] others think they failed quickly and catastrophically as massive floods.[7] Lava flows traveled downriver 76 miles (121 km) from river mile 178 to 254.

One lava flow, from Little Springs, south of Pliocene Mount Trumbull, has a cosmogenic helium age of 1300 +/- 500 years BP. Pottery shards dated to between 1050 and 1200 CE were found within the lava flow, produced around the same time as the Sunset Crater eruption in the San Francisco volcanic field on the South Rim.[1]

Notable Vents
NameElevationLocationLast eruption
metersfeetCoordinates
Mount Emma[8]----
Little Springs[8]---1050-1200 AD
Prospect Cone[8]----
Mount Trumbull[8]----
Vulcan's Forge[2]----
Vulcan's Throne[1][2]---73,000 years ago

See also

References
  1. "Uinkaret Field". Global Volcanism Program. Smithsonian Institution.
  2. Wood, Charles A.; Jűrgen Kienle (1993). Volcanoes of North America. Cambridge University Press. pp. 277–278. ISBN 0-521-43811-X.
  3. "Grand Canyon National Park – Geologic Formations (U.S. National Park Service)". U.S. National Park Service. 2007-03-29. Retrieved 2007-05-24.
  4. New Debris Flow at Lava Falls, at Grand Canyon River Guides. Accessed 5/26/09.
  5. Karlstrom, K., Crow, R., Peters, L., McIntosh, W., Raucci, J., Crossey, L., and Umhoefer, P., 2007, 40Ar/39Ar and field studies of Quaternary basalts in Grand Canyon and model for carving Grand Canyon: Quantifying the interaction of river incision and normal faulting across the western edge of the Colorado Plateau: GSA Bulletin, v. 119, no. 11/12, pp. 1283–1312.
  6. Hamblin, W.K., 1994, Late Cenozoic lava dams in the western Grand Canyon: Geological Society of America Memoir 183, 139 p.
  7. Fenton, C.R., Poreda, R.J., Nash, B.P., Webb, R.H., and Cerling, T.E., 2004, Geochemical discrimination of five Pleistocene lava-dam outburst-flood deposits, western Grand Canyon, Arizona: The Journal of Geology, v. 112, pp. 91–110, doi:10.1086/379694.
  8. "Uinkaret Field: Synonyms and Subfeatures". Global Volcanism Program. Smithsonian Institution. Retrieved 2007-05-23.
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