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112-750: Lassen Peak ( / ˈ l æ s ə n / LASS -ən ), 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

224-481: A Buddhist monastery ( Shasta Abbey , founded by Houn Jiyu-Kennett in 1971) to modern-day Native American rituals. A group of Native Americans from the McCloud River area practice rituals on the mountain. Mount Shasta has also been a focus for non-Native American legends, centered on a hidden city of advanced beings from the lost continent of Lemuria . The legend grew from an offhand mention of Lemuria in

336-478: A 9-year-old boy died from a collapsed retaining wall along the summit trail on July 29, 2009, the path closed for six years for construction, reopening in 2015. The mountain's summit trail can be accessed from a parking lot on the northern side of the California State Route 89. The Lassen Peak Trail, which starts from this parking area, runs for 2.5 mi (4.0 km) with switchback turns,

448-581: A Danish blacksmith, Peter Lassen , who guided immigrants past the peak to the Sacramento Valley during the 1830s. This trail was replaced by the Nobles Emigrant Trail , named for the guide William Nobles, who pioneered the trail in 1851. Lassen Peak's first recorded ascent took place in 1851, led by Grover K. Godfrey. In 1864, painter Helen Tanner Brodt became the first woman to reach the summit of Lassen Peak, wanting to sketch

560-482: A column that reached altitudes of more than 30,000 ft (9,100 m) and could be seen from the city of Eureka , 150 mi (240 km) to the west. This column underwent a partial collapse, generating a pyroclastic flow composed of hot ash, pumice, rock, and gas that destroyed 3 sq mi (7.8 km) of land and spawned a lahar extending 15 mi (24 km) from the volcano and again reaching Hat Creek Valley. Smaller mudflows also formed on every side of

672-453: A cryptodome was in the May 1980 eruption of Mount St. Helens , where the explosive eruption began after a landslide caused the side of the volcano to collapse, leading to explosive decompression of the subterranean cryptodome. A lava spine or lava spire is a growth that can form on the top of a lava dome. A lava spine can increase the instability of the underlying lava dome. A recent example of

784-578: A darkroom in a tent. He wrote of the eruption he witnessed on June 14, 1914, "The sight was fearfully grand." Loomis's pictures were published in his book Pictorial History of the Lassen Volcano (1926); a number of his original plates remain in the archives of the National Park Service. His photographs have been used to help understand the timeline and geology of the 1915 eruptions of Lassen Peak. One of Lassen Peak's 1917 eruptions

896-507: A few examples still remain). In the last 8,000 years, the Hotlum Cone has erupted at least eight or nine times. About 200 years ago, the last significant Mount Shasta eruption came from this cone and created a pyroclastic flow, a hot lahar (mudflow), and three cold lahars, which streamed 7.5 mi (12.1 km) down Mount Shasta's east flank via Ash Creek. A separate hot lahar went 12 mi (19 km) down Mud Creek. This eruption

1008-512: A flow front 400 metres (1,300 ft) tall (the dark scalloped line at lower left). There is another prominent coulée flow on the flank of Llullaillaco volcano, in Argentina , and other examples in the Andes . Mount Shasta Mount Shasta ( / ˈ ʃ æ s t ə / SHASS -tə ; Shasta : Waka-nunee-Tuki-wuki ; Karuk : Úytaahkoo ) is a potentially active stratovolcano at

1120-425: A flying humanoid creature with batlike features. They described what they saw as a man “stocky as Hulk Hogan, with leathery wings fifty feet from one end to the other and the face of a bat.” Despite the conflicting details, both accounts have been added to the legend of Batsquatch as additional proof. See news article here: https://pacsentinel.com/batsquatch/ About 593,000 years ago, andesitic lavas erupted in what

1232-432: A fully intact summit crater indicating Shastina developed after the last ice age . Shastina has been built by mostly pyroxene andesite lava flows. Some 9,500 years ago, these flows reached about 6.8 mi (10.9 km) south and 3 mi (4.8 km) north of the area now occupied by nearby Black Butte . The last eruptions formed Shastina's present summit about a hundred years later. But before that, Shastina, along with

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1344-617: A lava spine is the spine formed in 1997 at the Soufrière Hills Volcano on Montserrat. Coulées (or coulees) are lava domes that have experienced some flow away from their original position, thus resembling both lava domes and lava flows . The world's largest known dacite flow is the Chao dacite dome complex , a huge coulée flow-dome between two volcanoes in northern Chile . This flow is over 14 kilometres (8.7 mi) long, has obvious flow features like pressure ridges, and

1456-424: A length of 1,000 ft (300 m). On May 14, 1915, Lassen Peak erupted lava blocks, which extended as far as Manton , 20 mi (32 km) west of the mountain. By the next day, the volcano had produced a dacitic lava dome, between 63 and 68 percent silica, which occupied its summit crater. On May 19, a large eruption destroyed this dome, and a new crater formed at the summit. No lava erupted, but parts of

1568-781: A lightning strike started the Reading Fire 1 mi (1.6 km) to the northeast of the Paradise Meadow region, which was contained after it reached an area of 28,079 acres (113.63 km). During the summer and fall of 2016, the National Park Service carried out prescribed fires to help reduce the amount of fuel available for fires in the Mineral Headquarters area and the Manzanita and Juniper Lake areas, respectively. Lassen Peak supports

1680-399: A number of observers reported an eruption at Cinder Cone visible from more than 40 mi (64 km) away, with one observer near the mountain claiming to have observed a lava flow "running down the sides of the volcano." However, despite these testimonies and accounts in newspaper articles and several scientific journals, the veracity of these eruptions has been questioned by scientists from

1792-545: A number of the potentially active Californian volcanoes reside less than 100 mi (160 km) from highly populated areas, and explosive eruptions could produce ash that travels for several hundred miles. In the case of signs that suggest impending volcanic activity, the United States Geological Survey has a plan in place to utilize portable monitoring instruments, deploy scientists to the area, and implement an emergency response plan developed by

1904-495: A region to the east of the Devastated Area. On May 30, 1914, despite an apparent lack of precursor earthquakes, Lassen became volcanically active again after 27,000 years of dormancy , when it produced a steam explosion that carved out a small crater with a fairly deep lake on the volcano's summit. The crater grew as it was carved by more than 180 similar phreatic explosions over the span of more than 11 months, reaching

2016-452: A rough indicator of magma supply , but it shows no systematic relationship to the timing or characteristics of lava dome explosions. Gravitational collapse of a lava dome can produce a block and ash flow . A cryptodome (from the Greek κρυπτός , kryptos , "hidden, secret") is a dome-shaped structure created by accumulation of viscous magma at a shallow depth. One example of

2128-403: A round-trip hike 5 mi (8.0 km) in length that ascends approximately 2,000 ft (610 m) from the trailhead at 8,500 ft (2,600 m) to the summit at 10,457 ft (3,187 m). From the northeast summit, Lassen's 1915 mudflow and Prospect Peak are visible; the northwestern summit offers views of Lassen's two bowl-shaped craters and Mount Shasta, 80 mi (130 km) to

2240-419: A series of eruptions over a few years, undergoing significant glacial erosion between 25,000 and 18,000 years ago. The bowl-shaped depression on the volcano's northeastern flank, called a cirque , was eroded by a glacier that extended out 7 mi (11 km) from the dome. By 18,000 years ago, Lassen Peak started to form a mound-shaped dacite lava dome, pushing its way through Tehama's former northern flank. As

2352-542: A series of eruptions over the course of a few years. The mountain has been significantly eroded by glaciers over the last 25,000 years, and is now covered in talus deposits. On May 22, 1915, a powerful explosive eruption at Lassen Peak devastated nearby areas, and spread volcanic ash as far as 280 mi (450 km) to the east. This explosion was the most powerful in a series of eruptions from 1914 through 1917. Lassen Peak and Mount St. Helens in Washington were

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2464-528: A significant amount of snow and ice, these pyroclastic flows (or hot volcanic ash) might mix with water to form lahars (volcanically induced mudslides, landslides, and debris flows) that could destroy nearby communities. Dacitic eruptions could produce volcanic columns of gas and ash that could threaten aircraft in the area. Moreover, the Lassen volcanic center poses threats to visitors from sudden avalanches that could be entirely unrelated to eruptive activity. Due to

2576-581: A similar eruption today would threaten many lives and the northern Californian economy. Volcanic eruptions occur with similar frequency to major earthquakes from the San Andreas Fault , and at least 10 eruptions have taken place within the state during the past 1,000 years, the most recent at Lassen Peak. Under 1 percent of the state's population lives within hazard zones that could be affected by an eruption, but collectively hazard zones are visited by more than 20 million people each year. Moreover,

2688-513: A small number of global "power centers". Mount Shasta remains a focus of " New Age " attention. According to Guy Ballard , while hiking on Mount Shasta, he encountered a man who, introducing himself as the Count of St. Germain , is said to have started Ballard on the path to discovering the teachings that would become the "I AM" Activity religious movement. In 2009, a group of hikers were making their way up Mt. Shasta when they reported seeing

2800-409: A symmetrical pyroclastic cone. The youngest mafic volcano in the Lassen volcanic center, it is surrounded by unvegetated block lava and has concentric craters at its summit. Cinder Cone is comprised by five basaltic andesite and andesite lava flows, and it also has two cinder cone volcanoes, with two scoria cones, the first of which was mostly destroyed by lava flows from its base. In 1850 and 1851,

2912-486: A variety of flora that include mountain hemlock , whitebark pine , and alpine wildflowers . Mountain hemlocks generally only reach an elevation of 9,200 ft (2,800 m), while whitebark pines reach up to 10,000 ft (3,000 m). Throughout the national park, forests can be found featuring red fir , mountain alder, western white pine , white fir , lodgepole pine , Jeffrey pine , ponderosa pine , incense cedar , juniper , and live oak . Other plants found in

3024-409: Is disputed. Smithsonian Institution 's Global Volcanism Program says that the 1786 eruption is discredited, and that the last known eruption of Mount Shasta was around 1250 AD, proved by uncorrected radiocarbon dating. Although earlier Spanish explorers are likely to have sighted the mountain, the first written record and description was made in May 20, 1817 by Spaniard Narciso Durán, a member of

3136-491: Is exposed south of Mount Shasta's current summit and is called Misery Hill. It was formed 15,000 to 20,000 years ago from pyroxene andesite flows and has since been intruded by a hornblende dacite dome. There are many buried glacial scars on the mountain that were created in recent glacial periods ("ice ages") of the present Wisconsinian glaciation . Most have since been filled in with andesite lava , pyroclastic flows , and talus from lava domes. Shastina, by comparison, has

3248-408: Is now Mount Shasta's western flank near McBride Spring. Over time, an ancestral Mount Shasta stratovolcano was built to a large but unknown height; sometime between 300,000 and 360,000 years ago the entire north side of the volcano collapsed, creating an enormous landslide or debris avalanche , 6.5 cu mi (27 km ) in volume. The slide flowed northwestward into Shasta Valley , where

3360-790: Is now covered in broken rock fragments at the base of crags called talus deposits. Only its crag formations on its southern flank, near the summit trailhead, have not been significantly altered by glacial erosion. The Lassen volcanic center includes Brokeoff Volcano, Lassen's dacitic lava dome, and a number of small andesitic shield volcanoes found northeast of Lassen Peak. The Lassen dome field includes 30 dacitic lava domes such as Bumpass Mountain, Mount Helen, Ski Heil Peak, and Reading Peak; other major lava domes include Chaos Crags, Eagle Peak, Sunflower Flat, and Vulcans Castle. Nearby shield volcanoes include Prospect Peak and West Prospect Peak, and there are three cones close to Lassen Peak: Cinder Cone, Hat Mountain, and Raker Peak. The hydrothermal area inside

3472-451: Is part of a volcanic center that erupts from different vents, which each remain active for a number of years or decades but often do not erupt from the same vent twice, also known as a monogenetic volcanic field . 2000 years after Lassen's formation, it was surrounded by glaciers which ate away at its spiny protrusions of dacite. Due to glacial erosion from the last local glacial advance, which ceased roughly 15,000 years ago, Lassen's lava dome

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3584-513: Is stored within the region, tectonic setting, and how hydrothermal systems evolve over long periods of time. GPS receivers have been in place to monitor deformation within the Lassen volcanic center since 2008, and 13 seismometers in the vicinity, first installed in 1976 and since updated each decade, continually survey earthquakes within the locale. The Lassen Volcanic National Park is visited by more than 350,000 people every year. Incorporating more than 150 mi (240 km) of hiking trails, it

3696-535: Is the high viscosity of the lava that prevents it from flowing far from the vent from which it extrudes, creating a dome-like shape of sticky lava that then cools slowly in-situ. Spines and lava flows are common extrusive products of lava domes. Domes may reach heights of several hundred meters, and can grow slowly and steadily for months (e.g. Unzen volcano), years (e.g. Soufrière Hills volcano), or even centuries (e.g. Mount Merapi volcano). The sides of these structures are composed of unstable rock debris. Due to

3808-796: Is the second tallest peak in the California segment of the Cascades, behind 14,179 ft (4,322 m) Mount Shasta , which lies 80 mi (130 km) to the north. Due to its proximity to nearby volcanoes Mount Tehama and Mount Diller, it is not easy to distinguish from its neighboring peaks. Lassen Peak has the highest known winter snowfall amounts in California, with an average annual snowfall of 660 in (1,676 cm); in some years, more than 1,000 in (2,500 cm) of snow falls at its base elevation of 8,250 ft (2,515 m) at Lake Helen . The Lassen Peak area receives more precipitation (rain, sleet, hail, snow, etc.) than anywhere in

3920-560: Is visited by people looking to hike or backpack during the summers. Popular winter activities include snowshoeing and backcountry skiing . As the second-tallest volcano in Northern California, trailing only Mount Shasta, Lassen Peak is frequently visited by climbers and hikers from around the world. The summit opens for use most years near the end of June, remaining in use until heavy snow falls in October or November. After

4032-590: The 1980 eruption of Mount St. Helens , which had a volume of 0.24 cu mi (1.0 km). The region on the volcano's northeastern flank destroyed by the eruptions, 3 sq mi (7.8 km) in area, is now known as the Devastated Area, and it along with other deposits from the volcano has been altered by erosion and regrowth of vegetation, though the vegetation in Devastated Area is sparse due to its siliceous (rich in silica), nutrient-deprived soil, which cannot sustain normal tree growth due to its lack of water retention. Due to their small size and thin deposits,

4144-518: 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. Lassen Peak has a volume of 0.6 cu mi (2.5 km), making it one of the largest lava domes on Earth. The volcano arose from the former northern flank of now-eroded Mount Tehama about 27,000 years ago, from

4256-857: The Endangered Species Act of 1973 , and peregrine falcons , which were removed from the endangered species list in 1999. In forested areas below 7,800 ft (2,400 m), animals include American black bears , mule deer , martens , brown creepers , mountain chickadees , white-headed woodpeckers , long-toed salamanders , and several bat species. At higher elevations, Clark's nutcrackers , deer mice , and chipmunks can be found among mountain hemlock stands, and subalpine zones with sparse vegetation host populations of gray-crowned rosy finches , pikas , and golden-mantled ground squirrels . Among scattered stands of pinemat manzanita, red fir, and lodgepole pine, animals include dark-eyed juncos , montane voles , and sagebrush lizards . Meadows at

4368-558: The Lassen Volcanic National Park on August 9, 1916. The park, 106,372 acres (430.47 km) in area, can be reached from the California State Route 89 highway. Between 385,000 and 315,000 years ago, volcanism at the Lassen center shifted from andesitic stratovolcano construction to production of dacite domes. Over the past 300,000 years, the Lassen Peak area has produced more than 30 lava domes, Lassen Peak being

4480-533: The Pit River . Simultaneously, dacite lava with lower viscosity than dacite from the previous eruption filled the summit crater, overflowing and extending in two streams for 1,000 ft (300 m) down the mountain's western and northeastern sides. On May 22, 1915, at about 4:00 p.m., Lassen Peak produced a violent explosive eruption that ejected rock and pumice and formed a larger and deeper crater at its summit. Within 30 minutes, volcanic ash and gas formed

4592-671: The Shasta River now cuts through the 28-mile-long (45 km) flow. What remains of the oldest of Mount Shasta's four cones is exposed at Sargents Ridge on the south side of the mountain. Lavas from the Sargents Ridge vent cover the Everitt Hill shield at Mount Shasta's southern foot. The last lavas to erupt from the vent were hornblende - pyroxene andesites with a hornblende dacite dome at its summit. Glacial erosion has since modified its shape. The next cone to form

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4704-495: The Shasta–Trinity National Forest . The origin of the name " Shasta " is vague, either derived from a people of a name like it or otherwise garbled by early Westerners. Mount Shasta is connected to its satellite cone of Shastina , and together they dominate the landscape. Shasta rises abruptly to tower nearly 10,000 feet (3,000 m) above its surroundings. On a clear winter day, the mountain can be seen from

4816-647: The Siskiyou Trail , which runs at Mount Shasta's base. The Siskiyou Trail was on the track of an ancient trade and travel route of Native American footpaths between California's Central Valley and the Pacific Northwest . The California Gold Rush brought the first Euro-American settlements into the area in the early 1850s, including at Yreka, California and Upper Soda Springs . The first recorded ascent of Mount Shasta occurred in 1854 (by Elias Pearce), after several earlier failed attempts. In 1856,

4928-695: The U.S. National Geodetic Survey ; 1981 data from the Geographic Names Information System lists the mountain's elevation at 10,457 ft (3,187 m). Lassen Peak marks the southernmost major volcano in the Cascade Range , rising above the northern Sacramento Valley . Bounded by the Sacramento Valley and the Klamath Mountains to the west and the Sierra Nevada mountain range to the south, it

5040-512: The United States Geological Survey . In addition to the fact that cinder cones usually erupt lava from base vents, there is a lack of physical evidence suggesting activity at the volcano since its formation in 1650. In addition, an old willow bush growing near the summit crater that was documented during the 1850s was still present in the 1880s after the alleged eruptions, suggesting that no eruptions took place during

5152-528: The 1850s. The areas surrounding Lassen Peak, especially to its east, south, and southeast, represented a meeting ground for Maidu , Yana , Yahi , and Atsugewi Native Americans . The volcano is known among some native populations as Amblu Kai , which means "Mountain Ripped Apart" or "Fire Mountain," and as Kom Yamani, which means "Snow Mountain," among the Mountain Maidu . Because the area

5264-557: The 1880s, to a description of a hidden Lemurian village in 1925. In 1931, Harvey Spencer Lewis , using the pseudonym Wishar S[penle] Cerve, wrote Lemuria: the lost continent of the Pacific , published by AMORC , about the hidden Lemurians of Mount Shasta that cemented the legend in many readers' minds. In August 1987, believers in the spiritual significance of the Harmonic Convergence described Mount Shasta as one of

5376-416: The 1915 eruptions will likely not be well-preserved geologically. After 1915, steam explosions continued for several years, indicating extremely hot rock beneath Lassen Peak's surface. In May 1917, an especially strong steam explosion formed the northern crater on Lassen Peak's summit, with eruptions lasting two days and producing an ash cloud that extended 10,000 to 12,000 ft (3,000 to 3,700 m) into

5488-413: The 1950s, but have grown weaker over time; they can still be found among the volcano's summit craters. These hydrothermal features are monitored continuously for their physical and chemical conditions by the United States Geological Survey. Climbers reported steam eruptions in the summit craters for decades after activity apparently ceased in 1921, and the naturalist Paul Schulz documented 30 steam vents at

5600-529: The 21st century, with only a handful of small magnitude earthquakes and no demonstrable ground deformation . Although geophysically quiet, periodic geochemical surveys indicate that volcanic gas emanates from a fumarole at the summit of Mount Shasta from a deep-seated reservoir of partly molten rock. Mount Shasta can release volcanic ash , pyroclastic flows or dacite and andesite lava . Its deposits can be detected under nearby small towns. Mount Shasta has an explosive, eruptive history. There are fumaroles on

5712-488: The Below-World, Llao, who resided at Mount Mazama by throwing hot rocks and lava, probably representing the volcanic eruptions at both mountains. Italian settlers arrived in the early 1900s to work in the mills as stonemasons and established a strong Catholic presence in the area. Mount Shasta City and Dunsmuir, California , small towns near Shasta's western base, are focal points for many of these, which range from

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5824-615: The Cascade Range south of the Three Sisters volcanoes in Oregon. Though the volcano lies too far to the south to support a permanent snow cover over the entire mountain, the heavy annual snowfall on Lassen Peak creates fourteen permanent patches of snow on and around the mountain top, but no glaciers . Lightning has been known to strike the area frequently during summer thunderstorms. These can initiate fires. On July 23, 2012,

5936-623: The Cascade, the others being Crater Lake and the Kulshan Caldera at Mount Baker . Shortly after, the Lassen volcanic center, a cluster of closely spaced volcanoes, formed in the area, covering the nearby caldera. During the late Pleistocene it produced andesite lava flows that built the Brokeoff composite volcano (stratovolcano). Following the end of volcanism at Brokeoff Volcano hydrothermal fluids began chemically weathering minerals in

6048-588: The Fantastic Lava Beds . It also created the rockfalls at Chaos Jumbles. The only active Cascade volcano with an elevation above 10,000 ft (3,000 m) that is not a stratovolcano, Lassen Peak is a rhyodacitic lava dome. It represents one of the largest lava domes on Earth, with a height of 2,000 ft (610 m) above its surroundings, and an approximate volume of 0.60 cu mi (2.5 km). Unlike more conventional, conical stratovolcanoes like Mount Shasta or Mount Rainier, Lassen Peak

6160-493: The Lassen Peak National Monument in 1907. Despite Native population claims that Lassen Peak was "full of fire and water" and would erupt again, this motion was based on the general belief that Lassen Peak was now extinct , and that its vicinity contained intriguing volcanic phenomena, which could be studied and observed. Once the volcano became active again in 1914, the monument was expanded to establish

6272-640: The Lassen Peak area consist of coyote mint , lupines , mule's ears , ferns , corn lilies , red mountain heathers , pinemat manzanitas, greenleaf manzanitas , bush chinquapins , catchflies, Fremont's butterweed, buckwheat , granite gilia , mountain pride , mariposa tulips , creambush , and a variety of chaparral shrubs. The various habitats in the Lassen Volcanic National Park support about 300 vertebrate species like mammals, reptiles , amphibians , fish, and birds, including bald eagles , which are listed as "Threatened" under

6384-759: The Lassen Peak volcanic center, with features located southeast and southwest of Lassen Peak, represents the largest geothermal area in the United States besides the one present at Yellowstone National Park. The Chaos Crags, a series of five small lava domes, represent the youngest part of Lassen volcanic center's dome field, reaching an elevation of about 1,800 ft (550 m) above their surroundings. They were produced by vigorous explosive eruptions of pumice and ash followed by effusive activity, which created unstable edifices that partially collapsed and formed pyroclastic flows made of incandescent lava blocks and lithic ash. Six domes were originally formed, though one

6496-550: The Luis Antonio Argüello expedition into the upper areas of the Sacramento River Valley, who wrote "At about ten leagues to the northwest of this place we saw the very high hill called by soldiers that went near its slope Jesus Maria, It is entirely covered with snow." Peter Skene Ogden (a leader of a Hudson's Bay Company trapping brigade) in 1826 recorded sighting the mountain, and in 1827,

6608-697: The Morgan and Growler Hot Springs south of the national park in Mill Canyon. These are produced by the boiling of underground bodies of water, which generates steam. At Bumpass Hell, these features are at their most vigorous, with temperatures reaching 322 °F (161 °C) at Big Boiler, the park's biggest fumarole and one of the hottest hydrothermal fumaroles in the world. Because of their acidic conditions and heat, none of these hydrothermal bodies are safe for bathing except for at Drakesbad Guest Ranch. Fumaroles near Lassen Peak in particular remained active through

6720-401: The National Park Service if an eruption were imminent. Although basaltic lava flows are the most common eruptive activity in the Lassen volcanic center, they could also produce more violent and thus more hazardous silicic lava flows, in addition to building additional, unstable lava domes that could collapse and spawn pyroclastic flows that could extend for several miles. Because Lassen Peak has

6832-561: The Southern Cascades, one volcano becomes active and normally becomes extinct as another begins to erupt, but at the Lassen locus, the Maidu and Dittmar volcanic centers overlapped during the late Pliocene to the early Pleistocene . Volcanism within the Lassen vicinity follows a trend of intermittent, episodic eruptions punctuating long periods of dormancy, a pattern which persisted through the late Pleistocene and Holocene . During

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6944-584: The United States during the 20th century. Unlike eruptions at Mount Baker, Mount Rainier , Mount St. Helens, or Mount Hood during the 19th century, Lassen Peak's eruptions were very well documented by newspapers and extensively photographed. Though there is a large supply of images documenting these eruptions at Lassen Peak, the best and most complete images were taken by the local businessman Benjamin Franklin Loomis . Using an 8x10-inch camera with glass-plate negatives, Loomis made his own film and set up

7056-491: The andesite flows, altering the once strong rocks into easily eroded materials. Glaciers and streams were able to rapidly erode deep channels into these altered volcanic rocks, reducing the once lofty peak of Brokeoff Volcano into the landscape we see today. Following the erosion of Brokeoff Volcano, volcanism migrated to the Lassen Domefield to the northeast. Lassen Peak's lava dome formed about 27,000 years ago from

7168-899: The bottoms of valleys along streams and lakes support Pacific tree frogs , Western terrestrial garter snakes , common snipes , and mountain pocket gophers . Other animals found within the national park area include snakes like rubber boas , common garter snakes , and striped whipsnakes ; cougars ; amphibians like newts , salamanders , rough-skinned newts , and Cascades frogs ; 216 species of birds including MacGillivray's warblers , Wilson's warblers , song sparrows , spotted owls , northern goshawks , and bufflehead ducks; five species of native fish that include rainbow trout , tui chubs , speckled daces , Lahontan redsides , and Tahoe suckers ; and four invasive fish species including brook trout , brown trout , golden shiners , and fathead minnows . Prominent invertebrate species include California tortoiseshell butterflies. Lassen Peak lies near

7280-563: The construction of the Chaos Crag dome complex between 1100 and 1000 years ago and eruptions at Lassen Peak beginning in 1914. Prior to 1914, Lassen Peak likely underwent at least one explosive eruption, which created a summit crater 360 ft (110 m) deep with a diameter of 1,000 ft (300 m). Deposits from older mudflows that can be traced specifically to the Lassen dome have also been found in Hat Creek, Lost Creek, and in

7392-400: The dome fell on the upper flanks of the mountain, which were covered in more than 30 ft (9.1 m) of snow. The lava mixed with snow and rock to form a lahar (volcanically induced mudslide , landslide , and debris flow ), 0.5 mi (0.80 km) in width, which coursed down the side of the volcano, traveling 4 mi (6.4 km) and reaching Hat Creek . After being deflected to

7504-482: The first women (Harriette Eddy, Mary Campbell McCloud, and their party) reached the summit. By the 1860s and 1870s, Mount Shasta was the subject of scientific and literary interest. In 1854 John Rollin Ridge titled a poem "Mount Shasta." A book by California pioneer and entrepreneur James Hutchings , titled Scenes of Wonder and Curiosity in California , contained an account of an early summit trip in 1855. The summit

7616-493: The floor of the Central Valley 140 miles (230 km) to the south. The mountain has attracted the attention of poets, authors, and presidents. The mountain consists of four overlapping dormant volcanic cones that have built a complex shape, including the main summit and the prominent and visibly conical satellite cone of 12,330 ft (3,760 m) Shastina. If Shastina were a separate mountain, it would rank as

7728-453: The four largest ( Whitney , Bolam , Hotlum , and Wintun ) radiating down from high on the main summit cone to below 10,000 ft (3,000 m) primarily on the north and east sides. The Whitney Glacier is the longest, and the Hotlum is the most voluminous glacier in the state of California. Three of the smaller named glaciers occupy cirques near and above 11,000 ft (3,400 m) on

7840-532: The fourth-highest peak of the Cascade Range (after Mount Rainier , Rainier's Liberty Cap , and Mount Shasta itself). Mount Shasta's surface is relatively free of deep glacial erosion except, paradoxically, for its south side where Sargents Ridge runs parallel to the U-shaped Avalanche Gulch. This is the largest glacial valley on the volcano, although it does not now have a glacier in it. There are seven named glaciers on Mount Shasta, with

7952-510: The highest cone, the Hotlum Cone, formed about 8,000 years ago. It is named after the Hotlum glacier on its northern face; its longest lava flow, the 500-foot-thick (150 m) Military Pass flow, extends 5.5 mi (8.9 km) down its northeast face. Since the creation of the Hotlum Cone, a dacite dome intruded the cone and now forms the summit. The rock at the 600-foot-wide (180 m) summit crater has been extensively hydrothermally altered by sulfurous hot springs and fumaroles there (only

8064-402: The highly viscous lava in the dome's conduit . Domes undergo various processes such as growth, collapse, solidification and erosion . Lava domes grow by endogenic dome growth or exogenic dome growth. The former implies the enlargement of a lava dome due to the influx of magma into the dome interior, and the latter refers to discrete lobes of lava emplaced upon the surface of the dome. It

8176-425: The intermittent buildup of gas pressure , erupting domes can often experience episodes of explosive eruption over time. If part of a lava dome collapses and exposes pressurized magma, pyroclastic flows can be produced. Other hazards associated with lava domes are the destruction of property from lava flows , forest fires , and lahars triggered from re-mobilization of loose ash and debris. Lava domes are one of

8288-410: The largest. These lava domes formed as a result of rising lava that was pushed up but was too viscous to escape its source, creating steep edifices. Lassen Peak's lava dome formed 27,000 years ago from a series of eruptions over a few years, undergoing significant glacial erosion between 25,000 and 18,000 years ago. No volcanic activity took place 190,000 years ago to roughly 90,000 years ago, but during

8400-534: The last 100,000 years, there have been at least 12 periods of eruptive activity in the Lassen volcanic center, and since 90,000 years ago, the Twin Lakes sequence has been producing mixed lavas with variable appearances and compositions, including andesite and basaltic andesite lava flows and agglutinated volcanic cones (made of fused pyroclastic rocks) located by the Lassen dome field. The Twin Lakes sequence includes

8512-447: The lava dome grew it shattered overlaying rock, which formed a blanket of angular talus around the emerging steep-sided volcano. Likely resembling the nearby 1,100-year-old Chaos Crags , Lassen Peak reached its present height in a relatively short time, probably in just a few years. Within the past 1,000 years or so, activity at Lassen Peak has produced six dacite lava domes, erupted tephra and pyroclastic flows, and built Cinder Cone and

8624-549: The line of the Siskiyou Trail between California and Oregon, brought a substantial increase in tourism, lumbering, and population into the area around Mount Shasta. Early resorts and hotels, such as Shasta Springs and Upper Soda Springs , grew up along the Siskiyou Trail around Mount Shasta, catering to these early adventuresome tourists and mountaineers. In the early 20th century, the Pacific Highway followed

8736-507: The mountain, which show Mount Shasta is still alive. The worst-case scenario for an eruption is a large pyroclastic flow, similar to that which occurred in the 1980 eruption of Mount St. Helens . Since there is ice, such as Whitney Glacier and Mud Creek Glacier , lahars would also result. The United States Geological Survey monitors Mount Shasta and rates it as a very high-threat volcano. The summer climbing season runs from late April until October, although many attempts are made in

8848-501: The name "Sasty" or "Sastise" was given to nearby Mount McLoughlin by Ogden. An 1839 map by David Burr lists the mountain as Rogers Peak. This name was apparently dropped, and the name Shasta was transferred to present-day Mount Shasta in 1841, partly as a result of work by the United States Exploring Expedition . Beginning in the 1820s, Mount Shasta was a prominent landmark along what became known as

8960-585: The nearby Lassen National Forest and Lassen Peak, have become popular destinations for recreational activities, including climbing, hiking, backpacking, snowshoeing, kayaking, and backcountry skiing. Lassen Peak is dormant, meaning the volcano is merely inactive, and it has a functioning magma chamber under the ground still capable of eruptions. Thus it poses a threat to the nearby area through lava flows , pyroclastic flows , lahars (volcanically induced mudslides , landslides , and debris flows ), ash, avalanches , and floods. To monitor this threat, Lassen Peak and

9072-795: The north. The southern entrance to the park area has a winter sports area where visitors can ski , snowshoe , and within the Lassen National Forest, visitors can also bicycle, go boating , or use snowmobiles . Lava dome Existence of lava domes has been suggested for some domed structures on the Moon , Venus , and Mars , e.g. the Martian surface in the western part of Arcadia Planitia and within Terra Sirenum . Lava domes evolve unpredictably, due to non-linear dynamics caused by crystallization and outgassing of

9184-527: The northwest at Emigrant Pass, the lahar extended an additional 7 mi (11 km) down Lost Creek. On May 20, the lower Hat Creek valley flooded with muddy water, which damaged ranch houses in the Old Station area and caused minor injuries among a few people, all of whom escaped. Removing homes from their foundation, the lahar also uprooted trees more than 100 ft (30 m) tall. The flood continued for another 30 mi (48 km), killing fish in

9296-403: The only two volcanoes within the contiguous United States to erupt during the 20th century. Lassen Volcanic National Park, which encompasses an area of 106,372 acres (430.47 km), was created to preserve the areas affected by the eruption for future observation and study, to protect the nearby volcanic features, and to keep anyone from settling too close to the mountain. The park, along with

9408-440: The park with tiltmeters , seismometers , and inclinometers . Prior to 1996, geodetic surveys at Lassen Peak did not detect ground deformation, but Interferometric synthetic-aperture radar (InSAR) surveys between 1996 and 2000 suggested that downward subsidence was occurring at a rate of 0.39 in (10 mm) each year within a circular area with a diameter of 25 mi (40 km) centered just 3.1 mi (5 km) of

9520-469: The past 825,000 years, the area has produced hundreds of explosive eruptions over an area of 200 sq mi (520 km), and the past 50,000 years have seen seven major silicic eruptive episodes that produced dacitic lava domes , tephra , and pyroclastic flows , along with five periods of basaltic and andesitic lava flows . Local activity began 600,000 years ago with the formation of Brokeoff Volcano (alternatively known as Mount Tehama). Around

9632-497: The peak's inherent instability. The volcano is monitored by the California Volcano Observatory, which has a sensor network that can measure increased seismicity, ground deformation, or gas emissions suggesting movement of magma towards the surface near the volcano. The United States Geological Survey, in cooperation with the National Park Service, has been monitoring Lassen Peak and other volcanic areas in

9744-567: The principal structural features of many stratovolcanoes worldwide. Lava domes are prone to unusually dangerous explosions since they can contain rhyolitic silica -rich lava. Characteristics of lava dome eruptions include shallow, long-period and hybrid seismicity , which is attributed to excess fluid pressures in the contributing vent chamber. Other characteristics of lava domes include their hemispherical dome shape, cycles of dome growth over long periods, and sudden onsets of violent explosive activity. The average rate of dome growth may be used as

9856-622: The rest of the Cascade Volcanoes, and the other a smaller volume of low-potassium olivine tholeiitic basalt associated with the Basin and Range province. Within the region, most if not all of the volcanic rock has erupted in the past 3 million years. During this period, at least five large andesitic stratovolcanoes (such as Mount Maidu ) formed in the vicinity of Lassen Volcanic National Park, building volcanic cones before going extinct and undergoing erosion. For most volcanic centers in

9968-482: The same border, indicating that the Cascade Arc's southern end migrates at a rate of 0.4 to 1 in (1.0 to 2.5 cm) annually. In the southern segment of the Cascades, volcanoes exhibit widespread and long-lived activity produced by magma that ranges from low- silica basalt to siliceous (silica-rich) rhyolite . The Lassen volcanic center is fed by two magma chambers, one calc-alkaline reservoir common to

10080-617: The same time, about 614,000 years ago, an explosive eruption southwest of Lassen Peak produced 20 cu mi (83 km) of pumice and ash, covering the area between the vent and what is now the city of Ventura, California . This deposit, referred to as the Rockland tephra, reaches up to several inches in thickness within the San Francisco Bay area, and can be found as far as northern Nevada and southern Idaho . The same eruption also formed one of three known calderas within

10192-445: The season; during the spring, when meltwater is more abundant, fumaroles and pools of water have lower temperatures, while mudpots have more fluid mud supplies. During summer and droughts, they become drier and hotter, since they cannot be cooled by ground water. Geothermal activity can be observed at Bumpass Hell, Little Hot Springs Valley, Pilot Pinnacle, Sulphur Works, Devils Kitchen, Boiling Springs Lake, and Terminal Geyser, as well as

10304-454: The sky. Another 21 explosions occurred in June, further transforming the crater and creating a new vent on Lassen Peak's northwestern summit. More steam eruptions followed in June 1919 and similar activity was observed the next year, on April 8–9, 1920, followed by more steam eruptions lasting 10–12 hours in October of the same year. During February 1921, white steam erupted from eastern fissures on

10416-679: The south and southeast sides, including the Watkins , Konwakiton , and Mud Creek glaciers. The oldest-known human settlement in the area dates to about 7,000 years ago. At the time of Euro-American contact in the 1810s, the Native American tribes who lived within view of Mount Shasta included the Shasta , Okwanuchu , Modoc , Achomawi , Atsugewi , Karuk , Klamath , Wintu , and Yana tribes. A historic eruption of Mount Shasta in 1786 may have been observed by Lapérouse , but this

10528-472: The southern end of the Cascade Range in Siskiyou County, California . At an elevation of 14,179 ft (4,322 m), it is the second-highest peak in the Cascades and the fifth-highest in the state . Mount Shasta has an estimated volume of 85 cubic miles (350 cubic kilometers), which makes it the most voluminous volcano in the Cascade Volcanic Arc . The mountain and surrounding area are part of

10640-520: The southern end of the Cascade Volcanic Arc , at the western edge of the Basin and Range Province . Like other Cascade volcanoes, it was fed by magma chambers produced by the subduction of the oceanic Juan de Fuca tectonic plate under the western edge of the continental North American tectonic plate . The region is also affected geologically by the Cascadia subduction zone , which dips eastward beneath

10752-399: The summit in the 1950s. A report from the United States Geological Survey declared that "No one can say when, but it is almost certain that the Lassen area will experience volcanic eruptions again." Similarly, the California Volcano Observatory lists its threat level as "Very High." At the time of the early 20th century eruptions, the area surrounding the volcano was only sparsely populated, but

10864-412: The surrounding landscape. A tarn lake on Lassen Peak is named "Lake Helen" in her honor. The Bumpass Hell, a hydrothermal vent area near Lassen Peak, was named after a pioneer who suffered burns there and lost his leg shortly after. Other historic names for Lassen Peak include Mount Joseph (from 1827), Snow Butte, Sister Buttes, and Mount Lassen. United States President Theodore Roosevelt established

10976-983: The surrounding vicinity are closely observed with sensors by the California Volcano Observatory . Lassen Peak lies within Lassen Volcanic National Park , in Shasta County , California, 55 mi (89 km) east of the city of Redding . Lassen Peak and the rest of the National Park area are surrounded by the Lassen National Forest , which has an area of 1,200,000 acres (4,900 km). Nearby towns include Mineral in Tehama County and Viola in Shasta County. Lassen Peak reaches an elevation of 10,440 ft (3,180 m), according to 1992 data from

11088-439: The then forming Black Butte dacite plug dome complex to the west, created numerous pyroclastic flows that covered 43 sq mi (110 km ), including large parts of what is now Mount Shasta, California and Weed, California . Diller Canyon (400 ft or 120 m deep and 0.25 mi or 400 m wide) is an avalanche chute that was probably carved into Shastina's western face by these flows. The last to form, and

11200-499: The threat of an avalanche from nearby Chaos Crag if volcanic activity renewed in the area or an earthquake occurred, the Visitor Center for Lassen Peak located at Manzanita Lake closed in 1974. In 1993, a rockfall with a volume of 13,000 cu yd (9,900 m) fell down Lassen Peak's northeastern flank, but no visitors were harmed. Despite the volcano's current quiet state, rockfalls still pose significant hazards due to

11312-474: The track of the Siskiyou Trail to the base of Mount Shasta, leading to still more access to the mountain. Today's version of the Siskiyou Trail, Interstate 5 , brings thousands of people each year to Mount Shasta. From February 13–19, 1959, the Mount Shasta Ski Bowl obtained the record for the most snowfall during one storm in the U.S., with a total of 15.75 feet (480 cm). Mount Shasta

11424-438: The volcano, as well a layer of pumice and volcanic ash that reached as far as 25 mi (40 km) northeast; volcanic ash was detected up to 280 mi (450 km) east at the city of Elko, Nevada . Additionally, the lava flow on the volcano's northeastern flank was removed by this eruption, but not the similar deposit on the western flank. The eruptive output volume totaled 0.007 cu mi (0.029 km), dwarfed by

11536-509: The volcano. As a result, additional surveys using the Global Positioning System took place in 2004, and further InSAR surveys showed that subsidence continued through 2010. Lassen Peak is one of four Cascade volcanoes that has undergone subsidence since 1990, with Medicine Lake Volcano , Mount Baker, and Mount St. Helens. Though not conclusively linked to a possible eruption, this subsidence may offer insight into how magma

11648-405: The volcano. In total, about 400 eruptions were observed between 1914 and 1921, which were the last eruptions in the Cascades before the 1980 eruption of Mount St. Helens, which was the only other volcanic eruption in the contiguous United States during the 20th century. During its eruptions in the early 20th century, Lassen Peak attracted widespread media attention as the first volcano to erupt in

11760-483: The western coast of North America in the Pacific Northwest , as well as horizontal stretching to the east of crustal rock in the Basin and Range Province. About 3 million years ago, the southern limit of active volcanoes in the Cascades corresponded to the Yana Volcanic Center 19 mi (30 km) to the south of Lassen Peak, but currently the southern edge of the Lassen Volcanic National Park now marks

11872-399: The winter. Mount Shasta is also a popular destination for backcountry skiing . Many of the climbing routes can be descended by experienced skiers, and there are numerous lower-angled areas around the base of the mountain. No quota system currently exists for climbing Mount Shasta, and reservations are not required. However, climbers must obtain a summit pass and a wilderness permit to climb

11984-497: Was achieved (or nearly so) by John Muir , Josiah Whitney , Clarence King , and John Wesley Powell . In 1877, Muir wrote a dramatic popular article about his surviving an overnight blizzard on Mount Shasta by lying in the hot sulfur springs near the summit. This experience was inspiration to Kim Stanley Robinson 's short story "Muir on Shasta". The 1887 completion of the Central Pacific Railroad , built along

12096-586: Was captured on film by Justin Hammer from the nearby Catfish Lake. Originally silent, the film features sound effects added by his grandson, Craig Martin. The film was rediscovered and published in 2015 by the Shasta Historical Society . Lassen Peak remains an active volcano , as volcanic activity including fumaroles (steam vents), hot springs , and mudpots can be found throughout Lassen Volcanic National Park. Their activity varies based on

12208-650: Was declared a National Natural Landmark in December 1976. The "Shasta Gulch" is referenced in the lyrics to the 1994 song "Unfair" by cult indie rock band Pavement . The lore of some of the Klamath Tribes in the area held that Mount Shasta is inhabited by the Spirit of the Above-World, Skell, who descended from heaven to the mountain's summit at the request of a Klamath chief. Skell fought with Spirit of

12320-484: Was destroyed by a pyroclastic flow. Roughly 350 years ago, one of the domes collapsed to produce the Chaos Jumbles, an area where three enormous rockfalls transformed the local area and traveled as far as 4 mi (6.4 km) down the dome's slopes. Cinder Cone, which reaches an elevation of 700 ft (210 m) above its surrounding area in the northeastern region of the Lassen Volcanic National Park, forms

12432-489: Was not suitable for permanent habitation, there is relatively scarce archaeological evidence of a native presence in the Lassen area. The first white man to reach Lassen Peak was Jedediah Smith , who passed through the area in 1821 as he made his way for the western coast of the United States. After the California Gold Rush brought increased numbers of settlers into the area, Lassen Peak was named in honor of

12544-461: Was thought to have been observed by the explorer La Pérouse , from his ship off the California coast, in 1786, but this has been disputed. During the last 10,000 years, Mount Shasta has erupted an average of every 800 years, but in the past 4,500 years the volcano has erupted an average of every 600 years. USGS seismometers and GPS receivers operated by UNAVCO form the monitoring network for Mount Shasta. The volcano has been relatively quiet during

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