San Francisco Peaks
| San Francisco Peaks | ||
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 San Francisco Peaks in winter as seen from Elden Mountain |
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| Highest peak | Humphreys Peak ( 3850 m ) | |
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| Coordinates | 35 ° 20 ′ N , 111 ° 41 ′ W | |
The San Francisco Peaks (also San Francisco Mountain ) are a volcanic mountain range in the US state of Arizona immediately north of the city of Flagstaff and 80 km south of the Grand Canyon . The main mountain range is the stratovolcano San Francisco Mountain, the highest peak of which is Humphreys Peak at 3850 meters. As Flagstaff's " local mountain " , it gives the city a striking natural backdrop and is also the highest point in Arizona. The mountains are not near the city of San Francisco , they were named after their patron Francis of Assisi by a group of Spanish missionaries from the Order of the Franciscans in the 17th century .
In Navajo mythology, the San Francisco Mountains , known as Dook'o'oslííd , are the western limit of their traditional territory. They were created by the two gods Áltsé hastiin , the first man and Áltse adzáá , the first woman and attached to the sky with a ray of sunshine. The gods then adorned the mountains with abalone shells , brought the first gold warblers to the area and appointed Naadálgaii ashkii , the white corn boy and Naadáltsoii at'ééd , the yellow corn girl as the local gods of the mountains. The mountains also played an important role in the later creation story of the Navajo. The San Francisco Mountains are sacred to the Navajo. They are considered prayer and enlivened. Plans to expand the ski area in the mountains were therefore contested by the Navajo in court, citing the story of creation.
description
Today's mountain group emerged as a volcano and has the structure of a gently rising cone. In the center is known as Inner Basin called Caldera , the northeast in the Interior Valley is broken. The individual peaks were created by erosion from the original cone.
The mountains are covered by spruce forests and have snow-capped peaks. They offer numerous recreational opportunities, such as winter sports in the Arizona Snow Bowl ski area on the west flank, hiking, mountain biking and wildlife viewing. The San Francisco Peaks are located in the Coconino National Forest , a national forest under the administration of the US Forest Service . Around 75.8 km² of the mountains have been designated as a wilderness area under the name Kachina Peaks Wilderness since 1984 , the strictest class of nature reserves in the USA. In parts of the wilderness area, there are trails to protect the slopes threatened by erosion.
geology
The San Francisco Peaks are part of the San Francisco Volcanic Field , which covers 4,700 km² on the southern border of the Colorado Plateau. The field contains over 600 volcanoes that are less than 6 million years old; the last eruption was about 800 years ago. A geological hotspot is assumed to explain the origin of the volcanic field . The North American Plate shifts westward over it, so that its chimneys seem to move eastward. The oldest track is Kendrick Peak, the San Francisco Peaks are its largest structure, further to the east is the Sunset Crater , and since it is still active, in the future the east end - where the Canyon Diablo and the Meteor Crater are more impressive ones Landscapes are - new volcanoes arise.
The volcano was formed in five distinct phases and consists of a total volume of about 110 km³. From the distribution of the lava flows in the fourth and last major phase, it can be deduced that the volcano must have had a perfect cone shape around 430,000 years ago. Despite the distinctive peaks carved out of the volcanic cone by erosion, it is assumed that only around 7% of the rock volume was removed. They are mostly deposited in nine rubble compartments around the mountain range. The steep slopes in the Inner Basin and the Interior Valley were created by the erosive effects of glaciers . The extremely hard remains of the vent , which rise up as Core Ridge in the southwest of the caldera, were unaffected by this .
Most of the mountains in the San Francisco volcanic field are made up of basaltic magma , the magma with the lowest viscosity . The San Francisco Mountain, however, consists of andesite lava with medium viscosity and, with its gently sloping slopes, is similar to Mount Rainier or Fuji . It was created about 0.4 - 1 million years ago. The area is also rich in lava domes, which are made of silicate-rich rhyolite magma and, due to their relatively high viscosity, form steeply protruding geological structures. A classic example of such a lava dome is Elden Mountain on the outskirts of Flagstaff. The remains of the old lava flows and the tectonic fault lines (Mesa Butte Fault and Doney Fault) are easily recognizable on aerial photographs.
Web links
- US Federal Geological Institute datasheet on the volcanic field
- Land Use History of North America: San Francisco Peaks ( Memento from April 23, 2015 in the Internet Archive ) - joint project of the US Geological Survey and Northern Arizona University (copy in the Internet Archive, English)
- University at Buffalo: The brief but violent life of monogenetic volcanoes , October 3, 2012 (English)
Individual evidence
- ↑ Paul G. Zolbrod: Diné bahane '- Tha Navajo Creation Story . University of New Mexico Press, 1984. ISBN 0-8263-0735-3 . Page 88
- ↑ Kachina Peaks Wilderness. In: wilderness.net. Retrieved May 17, 2018 .
- ↑ The description is based on: Richard F. Holm: San Francisco Mountain - A late Cenozoic composite volcano in northern Arizona . In: Geological Society of America, Centennial Field Guide - Rocky Mountain Section , Volume 2. Boulder, Colorado, Geological Society of America, 1987, ISBN 0-8137-5406-2 , pages 389-392