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.
Novarupta is a volcano that was formed in 1912, located on the Alaska Peninsula on a slope of Trident Volcano in Katmai National Park and Preserve, about 290 miles (470 km) southwest of Anchorage. Formed during the largest volcanic eruption of the 20th century, Novarupta released 30 times the volume of magma of the 1980 eruption of Mount St. Helens.
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 Mazama is a complex volcano in the western U.S. state of Oregon, in a segment of the Cascade Volcanic Arc and Cascade Range. 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 Garibaldi is a dormant stratovolcano in the Garibaldi Ranges of the Pacific Ranges in southwestern British Columbia, Canada. It has a maximum elevation of 2,678 metres and rises above the surrounding landscape on the east side of the Cheakamus River in New Westminster Land District. In addition to the main peak, Mount Garibaldi has two named sub-peaks. Atwell Peak is a sharp, conical peak slightly higher than the more rounded peak of Dalton Dome. Both were volcanically active at different times throughout Mount Garibaldi's eruptive history. The northern and eastern flanks of Mount Garibaldi are obscured by the Garibaldi Névé, a large snowfield containing several radiating glaciers. Flowing from the steep western face of Mount Garibaldi is the Cheekye River, a tributary of the Cheakamus River. Opal Cone on the southeastern flank is a small volcanic cone from which a lengthy lava flow descends. The western face is a landslide feature that formed in a series of collapses between 12,800 and 11,500 years ago. These collapses resulted in the formation of a large debris flow deposit that fans out into the Squamish Valley.
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.
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.
Goat Rocks is an extinct stratovolcano in the Cascade Range, located between Mount Rainier and Mount Adams in southern Washington, in the United States. Part of the Cascade Volcanoes, it was formed by the subduction of the Juan de Fuca Plate under the western edge of the North American Plate. The volcano was active from 3.2 million years ago until eruptions ceased between 1 and 0.5 million years ago. Throughout its complex eruptive history, volcanism shifted from silicic explosive eruptions to voluminous, mafic activity.
Tskhouk-Karckar or Qarqar is a group of pyroclastic cones which is located in the central part of the Siunik volcanic ridge at the border of Armenia and Azerbaijan 60 km (37 mi) SE of Lake Sevan. The volcanoes lie on the northwest side of Tskhouk volcano and are constructed on a volcanic basement or rhyolites, basaltic andesites and dacites. The volcanoes erupted voluminous and long lava flows, grouped in three age-based stages of varying age and conservation. Petroglyphs have been found buried under the most recent stages and broken by earthquake activity, suggesting activity between the 4th–early 3rd millennium BC and 4720 ± 140 years BP, a date established by C14 analysis on graves inside the lava flows. There is evidence indicating that the last stage of activity resulted in abandonment of the area by humans, only resuming during the Middle Ages.
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.
Mount Price is a small stratovolcano in the Garibaldi Ranges of the Pacific Ranges in southwestern British Columbia, Canada. It has an elevation of 2,049 metres and rises above the surrounding landscape on the western side of Garibaldi Lake in New Westminster Land District. The mountain contains a number of subfeatures, including Clinker Peak on its western flank, which was the source of two thick lava flows between 15,000 and 8,000 years ago that ponded against glacial ice. These lava flows are structurally unstable, having produced large landslides as recently as the 1850s. A large provincial park surrounds Mount Price and other volcanoes in its vicinity. It lies within an ecological region that surrounds much of the Pacific Ranges.
Yamsay Mountain is a large shield volcano in the Cascade Range of south-central Oregon, located about 35 miles (56 km) east of Crater Lake on the border between Klamath County and Lake County. It is part of the Cascade Volcanic Arc but is located in a mountain range 30 to 50 miles behind the main Cascade volcanic front. The best known members of this enigmatic arc are the massive shields of Newberry Volcano, about 55 miles (89 km) farther north in Oregon, and Medicine Lake Volcano, about 80 miles (130 km) south in Northern California. Yamsay is the second highest volcano in the eastern arc, almost 300 feet (90 m) higher than Newberry and Medicine Lake.
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.
West Kelowna, formerly known as Westside and colloquially known as Westbank, is a city in British Columbia's Okanagan Valley on the west shore of Okanagan Lake. The city encompasses several neighbourhoods, including Casa Loma, Gellatly, Glenrosa, Lakeview Heights, Shannon Lake, Smith Creek, Rose Valley, Westbank, and West Kelowna Estates. As of 2021, West Kelowna had an estimated population of 36,078.
The Silverthrone Caldera is a potentially active caldera complex in southwestern British Columbia, Canada, located over 350 kilometres (220 mi) northwest of the city of Vancouver and about 50 kilometres (31 mi) west of Mount Waddington in the Pacific Ranges of the Coast Mountains. The caldera is one of the largest of the few calderas in western Canada, measuring about 30 kilometres (19 mi) long (north-south) and 20 kilometres (12 mi) wide (east-west). Mount Silverthrone, an eroded lava dome on the caldera's northern flank, which is 2,864 metres (9,396 ft) high, may be the highest volcano in Canada.
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 Mount Cayley volcanic field (MCVF) is a remote volcanic zone on the South Coast of British Columbia, Canada, stretching 31 km (19 mi) from the Pemberton Icefield to the Squamish River. It forms a segment of the Garibaldi Volcanic Belt, the Canadian portion of the Cascade Volcanic Arc, which extends from Northern California to southwestern British Columbia. Most of the MCVF volcanoes were formed during periods of volcanism under sheets of glacial ice throughout the last glacial period. These subglacial eruptions formed steep, flat-topped volcanoes and subglacial lava domes, most of which have been entirely exposed by deglaciation. However, at least two volcanoes predate the last glacial period and both are highly eroded. The field gets its name from Mount Cayley, a volcanic peak located at the southern end of the Powder Mountain Icefield. This icefield covers much of the central portion of the volcanic field and is one of the several glacial fields in the Pacific Ranges of the Coast Mountains.
Mount Samsari is a peak of the Abul-Samsari Range in Southern Georgia. The elevation of the mountain is 3,285 metres (10,778 ft) above sea level. Mount Samsari represents a volcanic cone, inside of which lies a caldera with a diameter of 3 kilometres (1.9 mi) with a semicircular ridge surrounding it. The formation of the caldera is linked to local fault systems. The floor of the caldera is lined with rocks and glacial debris as well as small lakes and contains volcanokarst formations. The caldera rim contains traces of previous glaciation, including cirques. The mountain was built up during the late Quaternary period and is made up of andesites, dacites and rhyolites. The slopes of Samsari are mainly devoid of vegetation. The caldera formed roughly 200ka ago.
The Bearwallow Mountain Andesite or Bearwallow Mountain Formation is a geologic formation exposed in and around the Mogollon Mountains of southwest New Mexico. It has a radiometric age of 27 to 23 million years, corresponding to the late Oligocene to early Miocene epochs.
The Coromandel Volcanic Zone (CVZ) is an extinct intraplate volcanic arc stretching from Great Barrier Island in the north, through the Coromandel Peninsula, to the Kaimai Range in the south. The area of transition between it and the newer and still active Taupō Volcanic Zone is now usually separated and is called the Tauranga Volcanic Centre. Its volcanic activity was associated with the formation and most active period of the Hauraki Rift.
