The Mono–Inyo Craters are a volcanic chain of craters, domes and lava flows in Mono County, Eastern California. The chain stretches 25 miles (40 km) from the northwest shore of Mono Lake to the south of Mammoth Mountain. The Mono Lake Volcanic Field forms the northernmost part of the chain and consists of two volcanic islands in the lake and one cinder cone volcano on its northwest shore. Most of the Mono Craters, which make up the bulk of the northern part of the Mono–Inyo chain, are phreatic volcanoes that have since been either plugged or over-topped by rhyolite domes and lava flows. The Inyo volcanic chain form much of the southern part of the chain and consist of phreatic explosion pits, and rhyolitic lava flows and domes. The southernmost part of the chain consists of fumaroles and explosion pits on Mammoth Mountain and a set of cinder cones south of the mountain; the latter are called the Red Cones.
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 volcanoes 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 10,457 ft (3,187 m) lava dome volcano in Lassen Volcanic National Park in Northern California. Located in the Shasta Cascade region above the northern Sacramento Valley, it is the southernmost active volcano in the Cascade Range of the Western United States, and part of the Cascade Volcanic Arc stretching from southwestern British Columbia to northern California. It supports many flora and fauna among its diverse habitats, which reach high elevations and are subject to frequent snowfall.
The Salton Sea is a shallow, landlocked, highly saline body of water in Riverside and Imperial counties at the southern end of the U.S. state of California. It lies on the San Andreas Fault within the Salton Trough, which stretches to the Gulf of California in Mexico.
The Imperial Valley of Southern California lies in Imperial and Riverside counties, with an urban area centered on the city of El Centro. The Valley is bordered by the Colorado River to the east and, in part, the Salton Sea to the west. Farther west lies the San Diego and Imperial County border. To the north is the Coachella Valley region of Riverside County, which together with Imperial Valley form the Salton Trough, or the Cahuilla Basin, also the county line of Imperial and Riverside counties, and to the south the international boundary with Mexico.
Mount Mazama is a complex volcano in the western U.S. state of Oregon, in a segment of the Cascade Volcanic Arc and Cascade Range. Most of the mountain collapsed following a major eruption approximately 7,700 years ago. The volcano is in Klamath County, in the southern Cascades, 60 miles (97 km) north of the Oregon–California border. Its collapse, due to the eruption of magma emptying the underlying magma chamber, formed a caldera that holds Crater Lake. Mount Mazama originally had an elevation of 12,000 feet (3,700 m), but following its climactic eruption this was reduced to 8,157 feet (2,486 m). Crater Lake is 1,943 feet (592 m) deep, the deepest freshwater body in the U.S. and the second deepest in North America after Great Slave Lake in Canada.
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.
An active volcano is a volcano that has erupted during the Holocene, is currently erupting, or has the potential to erupt in the future. A volcano that is not currently erupting but could erupt in the future is known as a dormant volcano. Volcanoes that will not erupt again are known as extinct volcanoes.
The Salton Sink is the low point of an endorheic basin, a closed drainage system with no outflows to other bodies of water, in the Colorado Desert sub-region of the Sonoran Desert. The sink falls within the larger Salton Trough and separates the Coachella Valley from the Imperial Valley, which are also segments of the Salton Trough. The lowest point of the sink is 269 ft (82 m) below sea level, and since 1906 the 343-square-mile (890 km2) Salton Sea has filled the lowest portion of the sink to a water depth of up to 43 ft (13 m).
The Alamo River flows west and north from the Mexicali Valley across the Imperial Valley (California). The 52-mile-long (84 km) river drains into the Salton Sea.
A complex volcano, also called a compound volcano or a volcanic complex, is a mixed landform consisting of related volcanic centers and their associated lava flows and pyroclastic rock. They may form due to changes in eruptive habit or in the location of the principal vent area on a particular volcano. Stratovolcanoes can also form a large caldera that gets filled in by a lava dome, or else multiple small cinder cones, lava domes and craters may develop on the caldera's rim.
The Imperial Fault Zone is a system of geological faults located in Imperial County in the Southern California region, and adjacent Baja California state in Mexico. It cuts across the border between the United States and Mexico.
The Brawley Seismic Zone (BSZ), also known as the Brawley fault zone, is a predominantly extensional tectonic zone that connects the southern terminus of the San Andreas Fault with the Imperial Fault in Southern California. The BSZ is named for the nearby town of Brawley in Imperial County, California, and the seismicity there is characterized by earthquake swarms.
Cerro Prieto is a volcano located approximately 29 km (18 mi) SSE of Mexicali in the Mexican state of Baja California. The volcano lies astride a spreading center associated with the East Pacific Rise. This spreading center is also responsible for a large geothermal field, which has been harnessed to generate electric power by the Cerro Prieto Geothermal Power Station.
The Alamo Canal was a 14 mi (23 km) long waterway that connected the Colorado River to the head of the Alamo River. The canal was constructed to provide irrigation to the Imperial Valley. A small portion of the canal was located in the United States but the majority of the canal was located in Mexico. The Alamo Canal is also known as the Imperial Canal.
The Salton Trough is an active tectonic pull-apart basin, or graben. It lies within the Imperial, Riverside, and San Diego counties of southeastern California and extends south of the Mexico–United States border into the state of Baja California.
Lake Cahuilla was a prehistoric lake in California and northern Mexico. Located in the Coachella and Imperial valleys, it covered surface areas of 5,700 km2 (2,200 sq mi) to a height of 12 m (39 ft) above sea level during the Holocene. During earlier stages of the Pleistocene, the lake reached even higher elevations, up to 31–52 m (102–171 ft) above sea level. During the Holocene most of the water came from the Colorado River with little contribution from local runoff; in the Pleistocene local runoff was higher and it is possible that Lake Cahuilla was supported solely from local water sources during the Wisconsin glaciation. The lake overflowed close to Cerro Prieto into the Rio Hardy, eventually draining into the Gulf of California.
The Salton Buttes are a group of volcanoes in Southern California, on the Salton Sea. They consist of a 7-kilometer (4.3 mi)-long row of five lava domes, named Mullet Island, North Red Hill, Obsidian Butte, Rock Hill and South Red Hill. They are closely associated with a fumarolic field and a geothermal field, and there is evidence of buried volcanoes underground. In pre-modern times Obsidian Butte was an important regional source of obsidian.
