The San Francisco volcanic field is a vast area covering more than 10,000 km22 containing cinder cones, lava fields, lava domes and the majestic (extinct) San Francisco Peaks, the highest of all mountains in Arizona, rising 5,000 feet above the surrounding plateau. The area presents some of Arizona's most impressive landscapes and geology.
The volcanic field is also the site of some of the USA's most recent volcanic activity, the formation of Sunset Crater cinder cone around AD 1100.
Type de volcan
polygenetic volcanic field, cinder cones, stratovolcano en sommeil
The large San Francisco Peaks stratovolcano was active between 1.4 million and 400,000 years ago and might have reached a height of 16,000 ft (ca. 5000 m).
Its summit collapsed, perhaps in a violent blast as did Mount St. Helens in 1980, creating a large caldera, known as the Inner Basin.
During 3 ice ages, glaciers carved deep valleys on its slopes, but volcanic activity continued, and built over 500 cinder cones, including the youngest, Sunset Crater which erupted less than 1000 years ago.
While the oldest volcanoes in the field were formed ca. 6 million years ago in the area near present-day Williams, volcanic activity of the field has progressively shifted eastward. The youngest eruptions are found 50 miles past Flagstaff to the Little Colorado River Valley, which is where the next eruption is most likely to occur. On average, eruptions have occurred every 10,000 years.
Native tribes of northern Arizona regard the San Francisco Peaks as a sacred place. The Hopi believe that the Peaks are the winter home of their kachina spirits and the source of clouds that bring rain for crops. The Peaks also play a prominent role in Navajo legends and ceremonies.
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