San Francisco volcanic field

For other uses, see San Francisco (disambiguation).
USGS Digital elevation model of the San Francisco volcanic field
SP Crater in the field is a cinder cone with a basalt lava flow that extends for 4 miles (6 km).

The San Francisco volcanic field is an area of volcanoes in northern Arizona, north of Flagstaff, USA. The field covers 1,800 square miles (4,700 km²) of the southern boundary of the Colorado Plateau. The field contains 600 volcanoes ranging in age from nearly 6 million years old to less than 1,000 years (Miocene to Holocene), of which Sunset Crater is the youngest.[1] The highest peak in the field is Humphreys Peak, at Flagstaff's northern perimeter: the peak is Arizona's highest at 12,633 feet (3,851 m) and is a part of the San Francisco Peaks, a dormant stratovolcano complex.


The volcanic field seems to have formed from a geological hotspot, a hot area in the mantle. As the North American plate moves over the spot, new volcanoes appear. Thus, the newest volcanoes are at the east side of the field. Most of the volcanoes are basalt cinder cones, but there are also large lava domes consisting of rhyolite and dacite.

Given that Sunset Crater is such a young volcanic feature of this area and that eruptions have occurred every several thousands of years in frequency, it is likely that there will be a future eruption in the San Francisco Volcanic field. However, it is impossible to predict when and exactly where a new eruption might occur. The United States Geological Survey does say that a future eruption would likely be in the eastern side of the volcanic field, where the most recent volcanic activity has occurred. Such an eruption is likely to be small and pose little hazard due to the remoteness of the area.

Visitation and usage

Popular tourist and hiking destinations in the volcanic field include the Kendrick Mountain Wilderness, 20 miles northwest of Flagstaff; and Sunset Crater, which is particularly popular because it is easily accessible and has interesting horizontal lava flows at the base of the crater.

Areas of the volcanic field have been used by NASA for testing techniques for exploration in a simulated extraterrestrial terrain environment.[2] NASA has also conducted the Desert Research and Technology Studies (DRATS) tests here.

Notable vents

Black Point lava flow in the San Francisco volcanic field. Little Colorado River at lower right. Astronaut photo from the International Space Station, 2009.
Name Elevation Location Last eruption
Bill Williams Mountain[3]2,8219,256 - 2.8 million years ago
Crater 160[4]1,9006,23235°30′N 111°36′W / 35.500°N 111.600°W / 35.500; -111.600 (Crater 160) -
Double Crater[5]2,4267,95935°20′44″N 111°27′5″W / 35.34556°N 111.45139°W / 35.34556; -111.45139 (Double Crater) -
Kendrick Peak[3]3,17510,418 - 1.4 million years ago
O'Leary Peak[3]2,7188,91635°24′05″N 111°31′36″W / 35.40139°N 111.52667°W / 35.40139; -111.52667 (O'Leary Peak)Pleistocene
San Francisco Peaks3,85112,63335°20′47″N 111°40′40″W / 35.34639°N 111.67778°W / 35.34639; -111.67778 (San Francisco Peaks) -
Mount Elden2,8359,30035°20′47″N 111°40′40″W / 35.34639°N 111.67778°W / 35.34639; -111.67778 (San Francisco Peaks) -
Sitgreaves Mountain[3] - - - 1.9 million years ago
SP Crater (SP Mountain)[6]2,1407,02135°34′56″N 111°37′55″W / 35.58222°N 111.63194°W / 35.58222; -111.63194 (SP Crater)71,000 years ago
Strawberry Crater 35°26′38″N 111°28′40″W / 35.44389°N 111.47778°W / 35.44389; -111.47778 (Strawberry Crater) -
Sunset Crater[3][7]2,4468,02635°21′51″N 111°30′11″W / 35.36417°N 111.50306°W / 35.36417; -111.50306 (Sunset Crater)950 ± 40 years
Sugarloaf Peak[3] - - - 220,000 years ago

See also


  1. Holm, R. F., and Moore, R. B., Holocene scoria cone and lava flows at Sunset Crater, northern Arizona, Geological Society of America Centennial Field Guide, 1987. pp. 393-7.
  3. 1 2 3 4 5 6 Wood, Charles A.; Jűrgen Kienle (1993). Volcanoes of North America. Cambridge University Press. pp. 278–281. ISBN 0-521-43811-X.
  4. "Crater 160, Arizona". Volcano World. Retrieved 7 May 2007.
  5. "Double Crater". Geographic Names Information System. United States Geological Survey.
  6. "SP Mountain, Arizona". Volcano World. Retrieved 7 May 2007.
  7. "Sunset Crater". Global Volcanism Program. Smithsonian Institution. Retrieved 7 May 2007.
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