Arizona, United States
Sunset Crater is a volcanic cinder cone located north of Flagstaff in U.S. State of Arizona. The crater is within the Sunset Crater Volcano National Monument.
Sunset Crater is the youngest in a string of volcanoes (the San Francisco volcanic field) that is related to the nearby San Francisco Peaks.
The eruptions forming the 340 meters-high cone were initially considered from tree-ring dating to have begun between the growing seasons of 1064-1065 AD; however, more recent paleomagnetic evidence places the onset of the eruption sometime between about 1080 and 1150 AD. The largest vent of the eruption, Sunset Crater itself, was the source of the Bonito and Kana-a lava flows that extended about 2.5 km NW and 9.6 km NE, respectively. Additional vents along a 10-km-long fissure extending SE produced small spatter ramparts and a 6.4-km-long lava flow to the east. The Sunset Crater eruption produced a blanket of ash and lapilli covering an area of more than 2100 sq km and forced the abandonment of settlements of the indigenous Sinagua Indians. The volcano has partially revegetated, with pines and wildflowers. The crater has given its name to the Sunset Crater Beardtongue (Penstemon clutei).
Damage from hikers forced the National Park Service to close a trail leading to the crater, but a short trail at the base remains.
The hiking trail below the summit skirts the substantial Bonito Lava Flow. This hardened lava is black and appears fresh as it has devastated the forest in its path. The lava flow also created an ice cave or tube that is now closed to the public after a partial collapse.
Sunset Crater Volcano National Monument
Sunset Crater Volcano National Monument is a U.S. National Monument in the north-central part of the U.S. state of Arizona, intended to protect Sunset Crater, a cinder cone that is part of the San Francisco Volcanic Field.
It is maintained by the National Park Service in close conjunction with nearby Wupatki National Monument. In the late 1920s, a Hollywood film company attempted to detonate large quantities of explosives inside Sunset Crater in order to simulate a volcanic eruption. Public outcry over this plan led in part to the proclamation of Sunset Crater Volcano National Monument by President Herbert Hoover in 1930.
A one mile (1.6 km) self-guided loop trail is located at the base of Sunset Crater but hiking to the summit is not permitted. A trail providing access to the summit and crater was closed in 1972 because of excessive erosion caused by hikers. A visitor center is located near the park entrance, 15 miles north of Flagstaff, Arizona along U.S. Highway 89.