Flagstaff is the county seat of Coconino County, Arizona, in the southwestern United States. As of the 2020 United States census, the city's population was 76,831.
Dacite is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz.
The Lassen volcanic area presents a geological record of sedimentation and volcanic activity in and around Lassen Volcanic National Park in Northern California, U.S. The park is located in the southernmost part of the Cascade Mountain Range in the Pacific Northwest region of the United States. Pacific Oceanic tectonic plates have plunged below the North American Plate in this part of North America for hundreds of millions of years. Heat and molten rock from these subducting plates has fed scores of volcanoes in California, Oregon, Washington and British Columbia over at least the past 30 million years, including these in the Lassen volcanic areas.
Chaos Crags is the youngest group of lava domes in Lassen Volcanic National Park, California. They formed as six dacite domes 1,100-1,000 years ago, one dome collapsing during an explosive eruption about 70 years later. The eruptions at the Chaos Crags mark one of just three instances of Holocene activity within the Lassen volcanic center. The cluster of domes is located north of Lassen Peak and form part of the southernmost segment of the Cascade Range in Northern California. Each year, a lake forms at the base of the Crags, and typically dries by the end of the summer season.
Mount Jefferson is a stratovolcano in the Cascade Volcanic Arc, part of the Cascade Range in the U.S. state of Oregon. The second highest mountain in Oregon, it is situated within Linn County, Jefferson County, and Marion County and forms part of the Mount Jefferson Wilderness. Due to the ruggedness of its surroundings, the mountain is one of the hardest volcanoes to reach in the Cascades. It is also a popular tourist destination despite its remoteness, with recreational activities including hiking, backpacking, mountaineering, and photography. Vegetation at Mount Jefferson is dominated by Douglas fir, silver fir, mountain hemlock, ponderosa pine, lodgepole pine, and several cedar species. Carnivores, insectivores, bats, rodents, deer, birds, and various other species inhabit the area.
The San Francisco volcanic field is an area of volcanoes in northern Arizona, north of Flagstaff, US. 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, of which Sunset Crater is the youngest. The highest peak in the field is Humphreys Peak, at Flagstaff's northern perimeter: the peak is Arizona's highest at 12,633 feet and is a part of the San Francisco Peaks, an active stratovolcano complex.
The San Francisco Peaks are a volcanic mountain range in the San Francisco volcanic field in north central Arizona, just north of Flagstaff and a remnant of the former San Francisco Mountain. The highest summit in the range, Humphreys Peak, is the highest point in the state of Arizona at 12,633 feet (3,851 m) in elevation. The San Francisco Peaks are the remains of an eroded stratovolcano. An aquifer within the caldera supplies much of Flagstaff's water while the mountain itself is in the Coconino National Forest, a popular recreation site. The Arizona Snowbowl ski area is on the western slopes of Humphreys Peak, and has been the subject of major controversy involving several tribes and environmental groups.
The Coconino National Forest is a 1.856-million acre United States National Forest located in northern Arizona in the vicinity of Flagstaff, with elevations ranging from 2,600 feet to the highest point in Arizona at 12,633 feet. Originally established in 1898 as the "San Francisco Mountains National Forest Reserve", the area was designated a U.S. National Forest by Pres. Theodore Roosevelt on July 2, 1908, when the San Francisco Mountains National Forest Reserve was merged with lands from other surrounding forest reserves to create the Coconino National Forest. Today, the Coconino National Forest contains diverse landscapes, including deserts, ponderosa pine forests, flatlands, mesas, alpine tundra, and ancient volcanic peaks. The forest surrounds the towns of Sedona and Flagstaff and borders four other national forests; the Kaibab National Forest to the west and northwest, the Prescott National Forest to the southwest, the Tonto National Forest to the south, and the Apache-Sitgreaves National Forest to the southeast. The forest contains all or parts of nine designated wilderness areas, including the Kachina Peaks Wilderness, which includes the summit of the San Francisco Peaks. The headquarters are in Flagstaff. The Coconino National Forest consists of three districts: Flagstaff Ranger District, Mogollon Rim Ranger District, and Red Rock Ranger District, which have local ranger district offices in Flagstaff, Happy Jack, and Sedona.
Mount Taylor is a dormant stratovolcano in northwest New Mexico, northeast of the town of Grants. It is the high point of the San Mateo Mountains and the highest point in the Cibola National Forest.
La Garita Caldera is a large caldera and extinct supervolcano in the San Juan volcanic field in the San Juan Mountains around the town of Creede in southwestern Colorado, United States. It is west of La Garita, Colorado. The eruption that created the La Garita Caldera is among the largest known volcanic eruptions in Earth's history, as well as being one of the most powerful known supervolcanic events.
The geology of the Australian Capital Territory includes rocks dating from the Ordovician around 480 million years ago, whilst most rocks are from the Silurian. During the Ordovician period the region—along with most of eastern Australia—was part of the ocean floor. The area contains the Pittman Formation consisting largely of quartz-rich sandstone, siltstone and shale; the Adaminaby Beds and the Acton Shale.
Kendrick Peak or Kendrick Mountain is one of the highest peaks in the San Francisco volcanic field north of the city of Flagstaff in the U.S. state of Arizona and is located on the Coconino Plateau in Coconino County.
Granite Mountain is a 7,628-foot (2,325 m) mountain located in Yavapai County, Arizona that covers roughly 12 square miles (31 km2). It was once known as Mount Gurley, for the first governor of the Arizona Territory, John A. Gurley. Its southwest face has a sheer granite cliff approximately 500 feet high that is one of the best locations for rock climbing in the state of Arizona. It is located in the Granite Mountain Wilderness, which is managed as a part of the Prescott National Forest. The mountain stands at the northern end of the Sierra Prietas, and borders Skull Valley on the west, on the northwest by the Santa Maria Mountains, and east by the Williamson Valley.
Taapaca is a Holocene volcanic complex in northern Chile's Arica y Parinacota Region. Located in the Chilean Andes, it is part of the Central Volcanic Zone of the Andean Volcanic Belt, one of four distinct volcanic chains in South America. The town of Putre lies at the southwestern foot of the volcano.
Red Mountain is a volcanic cinder cone located in the Coconino National Forest of northern Arizona, United States, 25 miles northwest of Flagstaff. It rises 1,000 feet (300 m) above the surroundings terrain and is shaped like the letter "U", with its opening towards the west. Geological Survey (USGS) and Northern Arizona University scientists suggest that Red Mountain was formed in eruptions nearly 740,000 years ago.
Strawberry Crater is a cinder cone volcano, more than 1,000 feet (300 m) high, in the San Francisco volcanic field, 20 miles (32 km) north of Flagstaff, Arizona. It is along Forest Road 545 between the Wupatki National Monument and Sunset Crater National Monument in the Strawberry Crater Wilderness. The crater lies in a volcanic field at a base elevation of about 5,500 feet (1,700 m), and prominence heights of about 6,526 feet (1,989 m). The northwestern end of the crater is covered with lava flows, while the southern end is filled with low cinder cones. Several of the surrounding cones include the better known, taller and younger Sunset Crater in the adjacent Sunset Crater National Monument.
Shahsavaran is a volcanic field in Iran. It covers an ellipse shaped area west of Bazman volcano. The field has erupted lava cones and lava flows, along with some explosive volcanic activity especially in the eastern part of the field. Volcanic rocks in the field are dominated by andesite, with subordinate basalt, dacite and rhyodacite. The volcanism has lasted from 12 million years ago to recent times, the 2010 Hosseinabad earthquake took place within the field but seems to be unrelated to volcanic activity.
Mount Cayley is an eroded but potentially active stratovolcano in the Pacific Ranges of southwestern British Columbia, Canada. Located 45 km (28 mi) north of Squamish and 24 km (15 mi) west of Whistler, the volcano resides on the edge of the Powder Mountain Icefield. It consists of massif that towers over the Cheakamus and Squamish river valleys. All major summits have elevations greater than 2,000 m (6,600 ft), Mount Cayley being the highest at 2,385 m (7,825 ft). The surrounding area has been inhabited by indigenous peoples for more than 7,000 years while geothermal exploration has taken place there for the last four decades.
The geology of Arizona began to form in the Precambrian. Igneous and metamorphic crystalline basement rock may have been much older, but was overwritten during the Yavapai and Mazatzal orogenies in the Proterozoic. The Grenville orogeny to the east caused Arizona to fill with sediments, shedding into a shallow sea. Limestone formed in the sea was metamorphosed by mafic intrusions. The Great Unconformity is a famous gap in the stratigraphic record, as Arizona experienced 900 million years of terrestrial conditions, except in isolated basins. The region oscillated between terrestrial and shallow ocean conditions during the Paleozoic as multi-cellular life became common and three major orogenies to the east shed sediments before North America became part of the supercontinent Pangaea. The breakup of Pangaea was accompanied by the subduction of the Farallon Plate, which drove volcanism during the Nevadan orogeny and the Sevier orogeny in the Mesozoic, which covered much of Arizona in volcanic debris and sediments. The Mid-Tertiary ignimbrite flare-up created smaller mountain ranges with extensive ash and lava in the Cenozoic, followed by the sinking of the Farallon slab in the mantle throughout the past 14 million years, which has created the Basin and Range Province. Arizona has extensive mineralization in veins, due to hydrothermal fluids and is notable for copper-gold porphyry, lead, zinc, rare minerals formed from copper enrichment and evaporites among other resources.
