Twin Buttes | |
---|---|
Highest point | |
Elevation | 5,351 ft (1,631 m) [1] |
Coordinates | 40°46′50″N121°35′33″W / 40.7804364°N 121.5924841°W Coordinates: 40°46′50″N121°35′33″W / 40.7804364°N 121.5924841°W [2] |
Geography | |
Location | Shasta County, California, U.S. |
Parent range | Cascade Range |
Topo map | USGS Burney Mountain East |
Geology | |
Age of rock | Late Pleistocene |
Mountain type | Cinder cone |
Volcanic arc | Cascade Volcanic Arc |
The Twin Buttes are two volcanic cinder cones located in the Cascade Mountain Range in Shasta County, California. They are part of the Bidwell Spring chain and lie within a region that was active in the Quaternary. Formed during the Pleistocene between 25,000 and 15,000 years ago, the volcanoes erupted lava flows that coursed toward the Burney Mountain lava dome. These lava flows cover an area of 3.9 square miles (10.1 km2) and are made of basalt and dacite. The volcanoes also erupted cinder and volcanic ash that reached eastward.
As of 2012, the Twin Buttes were still monitored by the United States Geological Survey for deformation, an indicator of pre-eruptive activity. However, they are considered to have "low to very low" threat potential for future eruptive activity.
The Twin Buttes are two cinder cone volcanoes [3] that lie north of Lassen Peak [1] in Shasta County, California. [4] The Twin Buttes reach a summit elevation of about 5,351 feet (1,631 m). [1] [a] Nearby towns include Burney, Old Station, and Viola. [4] About 6,700 people live within 19 miles (30 km) of the volcanoes, though the population within 62 miles (100 km) climbs to more than 260,000. [1] The buttes are aligned north–northwest and lie at the center of the Bidwell Spring volcanic chain. [3]
The Twin Buttes — and other volcanoes near Lassen Peak — are part of the Cascade Volcanic Arc, which was produced by subduction of the oceanic Juan de Fuca tectonic plate under the North American tectonic plate. [5] [6] Volcanic activity in the region is also influenced by the westward expansion of the Basin and Range Province into the Cascades. [7] Volcanism in the region encompasses a wide variety of eruption types, ranging from cinder cones to shield volcanoes. Eruptive activity has for the most part produced overlapping, mafic volcanoes through nonexplosive to weak explosive eruptions. [5] Volcanic activity during the Quaternary has produced basalt, basaltic andesite, and olivine tholeiite. [8] Other major volcanic centers near the Twin Buttes include the Yana, Maidu, Dittmar, and Latour centers, which were long-lived volcanic systems with magma ranging in composition from andesite to silicic rhyolite; these four systems are now eroded with extinct hydrothermal systems. [5]
The Bidwell Spring chain consists of five eruptive units including the Twin Buttes basalt. 40Ar/39Ar has placed two other deposits, basaltic andesite from Black Butte and andesite from Bidwell Spring, at 62,000 ± 10,000 years old and 68,000 ± 6,000 years old, respectively. These results suggest several small eruptions between 65,000 and 45,000 years ago from the Bidwell Spring chain. [9] Two other basaltic andesite deposits from the chain have been described by the United States Geological Survey (USGS), which considers the Bidwell Spring chain as part of the Caribou Volcanic Field, [10] [11] a system of 11 eruptive sequences between 200,000 and 100,000 years ago with vents aligned with faults that focused surface volcanic activity. [12] Basalt from the Twin Buttes overlies eruptive material from the Poison Lake Chain and the Cone Lake Chain, which are also within the Caribou Volcanic field. [12] Twin Buttes basalt is overlain by basaltic andesite erupted during the late Pleistocene from an unnamed volcanic vent, which is thought to be between 45,000 and 25,000 years old. [3]
Subfeatures of the formation include Red Rock Hill, which has an elevation of 5,240 feet (1,597 m). [1] Other nearby features include basaltic andesite and a distinct basalt deposit southeast and northeast of the Twin Buttes, respectively, both of which were produced by eruptive activity between 50,000 and 35,000 years ago. [13]
Located in an area that was highly active during the Quaternary, the Twin Buttes volcanoes formed during the late Pleistocene. [14] [b] The North and South Twin Buttes erupted blocky, partially unvegetated lava flows that moved north toward the southeastern base of Burney Mountain, a lava dome, [1] between 25,000 and 15,000 years ago, covering an area of 3.9 square miles (10.1 km2). They have an overall volume of 1.23 cubic kilometres (0.296 cu mi). [13] Eruptive material consisted of basalt (including picrite basalt) and dacite. [1] Basalt erupted from Twin Buttes forms part of the Bidwell Spring chain with an 40Ar/39Ar age of about 46,000 ± 3,000 years, [9] covering an area of 7.6 square miles (19.8 km2). The basalt deposit has a total volume of 0.19 cubic miles (0.8 km3). [13] At the edges, lava flows are steep, with up to 33 feet (10 m) of relief. [3] The lava flows from the Twin Buttes are porphyritic with about 53% silica content; they have vesicular surfaces and dense interiors. Phenocrysts range from 0.020 to 0.039 inches (0.5 to 1 mm); there are also coarse xenoliths of quartz throughout the lava flows. [3] Cinder and volcanic ash erupted by the Twin Buttes extend to the east. [3]
While Twin Buttes last erupted during the late Pleistocene, the area is still monitored by the USGS given its proximity to Lassen Peak. As of 2012, there were three GPS receivers continuously monitoring Twin Buttes for deformation, an indicator of pre-eruptive activity. [15] In 2014, the USGS considered Twin Buttes to have "low to very low" threat potential for a future eruption. [16]
Mount Bachelor, formerly named Bachelor Butte, is a dormant stratovolcano atop a shield volcano in the Cascade Volcanic Arc and the Cascade Range of central Oregon. Named Mount Bachelor because it stands apart from the nearby Three Sisters, it lies in the eastern segment of the central portion of the High Cascades, the eastern segment of the Cascade Range. The volcano lies at the northern end of the 15-mile (24 km) long Mount Bachelor Volcanic Chain, which underwent four major eruptive episodes during the Pleistocene and the Holocene. The United States Geological Survey considers Mount Bachelor a moderate threat, but Bachelor poses little threat of becoming an active volcano in the near future. It remains unclear whether the volcano is extinct or just inactive.
A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid lava, which travels farther and forms thinner flows than the more viscous lava erupted from a stratovolcano. Repeated eruptions result in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form.
Lassen Volcanic National Park is an American national park in northeastern California. The dominant feature of the park is Lassen Peak, the largest plug dome volcano in the world and the southernmost volcano in the Cascade Range. Lassen Volcanic National Park is one of the few areas in the world where all four types of volcano can be found—plug dome, shield, cinder cone, and stratovolcano.
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.
Lassen Peak, commonly referred to as Mount Lassen, is a lava dome volcano and the southernmost active volcano in the Cascade Range of the Western United States. Located in the Shasta Cascade region of Northern California, it is part of the Cascade Volcanic Arc, which stretches from southwestern British Columbia to northern California. Lassen Peak reaches an elevation of 10,457 ft (3,187 m), standing above the northern Sacramento Valley. It supports many flora and fauna among its diverse habitats, which are subject to frequent snowfall and reach high elevations.
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.
Cinder Cone is a cinder cone volcano in Lassen Volcanic National Park within the United States. It is located about 10 mi (16 km) northeast of Lassen Peak and provides an excellent view of Brokeoff Mountain, Lassen Peak, and Chaos Crags.
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.
Mount Washington is a deeply eroded volcano in the Cascade Range of Oregon. It lies within Deschutes and Linn counties and is surrounded by the Mount Washington Wilderness area.
Belknap Crater is a shield volcano in the Cascade Range in the U.S. state of Oregon. Located in Linn County, it is associated with lava fields and numerous subfeatures including the Little Belknap and South Belknap volcanic cones. It lies north of McKenzie Pass and forms part of the Mount Washington Wilderness. Belknap is not forested and most of its lava flows are not vegetated, though there is some wildlife in the area around the volcano, as well as a number of tree molds formed by its eruptive activity.
Medicine Lake Volcano is a large shield volcano in northeastern California about 30 mi (50 km) northeast of Mount Shasta. The volcano is located in a zone of east-west crustal extension east of the main axis of the Cascade Volcanic Arc and the Cascade Range. The 0.6 mi (1 km) thick shield is 22 mi (35 km) from east to west and 28 to 31 mi from north to south, and covers more than 770 sq mi (2,000 km2). The underlying rock has downwarped by 0.3 mi (0.5 km) under the center of the volcano. The volcano is primarily composed of basalt and basaltic andesite lava flows, and has a 4.3 by 7.5 mi caldera at the center.
Mount Tehama is an eroded andesitic stratovolcano in the Cascade Volcanic Arc and the Cascade Range in Northern California. Part of the Lassen volcanic area, its tallest remnant, Brokeoff Mountain, is itself the second highest peak in Lassen Volcanic National Park and connects to the park's highest point, Lassen Peak. Located on the border of Tehama County and Shasta County, Brokeoff's peak is the highest point in the former. The hikers that summit this mountain each year are treated to "exceptional" views of Lassen Peak, the Central Valley of California, and many of the park's other features. On clear days, Mount Shasta can also be seen in the distance.
The Garibaldi Volcanic Belt is a northwest–southeast trending volcanic chain in the Pacific Ranges of the Coast Mountains that extends from Watts Point in the south to the Ha-Iltzuk Icefield in the north. This chain of volcanoes is located in southwestern British Columbia, Canada. It forms the northernmost segment of the Cascade Volcanic Arc, which includes Mount St. Helens and Mount Baker. Most volcanoes of the Garibaldi chain are dormant stratovolcanoes and subglacial volcanoes that have been eroded by glacial ice. Less common volcanic landforms include cinder cones, volcanic plugs, lava domes and calderas. These diverse formations were created by different styles of volcanic activity, including Peléan and Plinian eruptions.
The Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 miles (1,100 km). The arc formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River which is the northward limit of the Cascade Range proper.
West Crater is a small lava dome with associated lava flows in southern Washington, United States. Located in Skamania County, it rises to an elevation of 4,131 feet (1,259 m), and forms part of the Cascade Volcanic Arc. It is also part of the Marble Mountain-Trout Creek Hill volcanic field, a little-known Quaternary volcanic field in the southern Cascades of Washington state. The area can be hiked, and can be accessed by roads in the Gifford Pinchot National Forest.
Black Crater is a shield volcano in the Western Cascades in Deschutes County, Oregon. Located near McKenzie Pass, the volcano has a broad conical shape with gentle slopes. The volcano likely formed during the Pleistocene and has not been active within the last 50,000 years. Eruptive activity at the volcano produced mafic lava flows made of basaltic andesite and olivine basalt; it also formed a number of cinder cones. A normal fault occurs on the western side of the volcano, trending north–south. The volcano has been eroded by glaciers, which carved a large cirque into the northeastern flank of the mountain, forming its current crater.
Pelican Butte is a steep-sided dormant shield volcano in the Cascade Range of southern Oregon. It is located 28 miles (45 km) due south of Crater Lake and 12 miles (19 km) northeast of Mount McLoughlin, and rises over 3,800 feet (1,200 m) directly above the shore of Upper Klamath Lake. Ice age glaciers carved a large cirque into the northeast flank of the mountain, forming a steep bowl which is popular in winter with backcountry skiers and snowmobilers. Several proposals have been made over the last few decades for ski area development on the northeast flanks, but none of the proposals has obtained the regulatory approval from the United States Forest Service necessary to proceed with construction. If the ski area is ever built, its skiable vertical of over 3,800 feet (1,200 m) would be the largest in Oregon exceeding the 3,590 feet (1,090 m) of Timberline Lodge ski area on Mount Hood.
The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.
The Canadian Cascade Arc, also called the Canadian Cascades, is the Canadian segment of the North American Cascade Volcanic Arc. Located entirely within the Canadian province of British Columbia, it extends from the Cascade Mountains in the south to the Coast Mountains in the north. Specifically, the southern end of the Canadian Cascades begin at the Canada–United States border. However, the specific boundaries of the northern end are not precisely known and the geology in this part of the volcanic arc is poorly understood. It is widely accepted by geologists that the Canadian Cascade Arc extends through the Pacific Ranges of the Coast Mountains. However, others have expressed concern that the volcanic arc possibly extends further north into the Kitimat Ranges, another subdivision of the Coast Mountains, and even as far north as Haida Gwaii.
The Sand Mountain Volcanic Field is a volcanic field in the upper McKenzie River watershed, located in the United States in Oregon. Part of the Cascade Volcanic Arc, it lies southwest of Mount Jefferson and northwest of Belknap Crater and Mount Washington. Its highest elevation is 5,463 feet (1,665 m).