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Mount Mazama (''Giiwas'' in the Native American language Klamath) is a
complex volcano 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 t ...
in the state of
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, in a segment of the Cascade Volcanic Arc and
Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...
. Most of the mountain collapsed following a major eruption approximately 7,700 years ago. The
volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...
is in Klamath County, in the southern Cascades, north of the Oregon–
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
border. Its collapse formed a
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
that holds Crater Lake. The mountain is in
Crater Lake National Park Crater Lake National Park is an American national park located in southern Oregon. Established in 1902, Crater Lake is the fifth-oldest national park in the United States and the only national park in Oregon. The park encompasses the caldera of ...
. Mount Mazama originally had an elevation of , but following its climactic eruption this was reduced to . Crater Lake is deep, the deepest freshwater body in the US and the second deepest in North America after
Great Slave Lake Great Slave Lake (french: Grand lac des Esclaves), known traditionally as Tıdeè in Tłı̨chǫ Yatıì (Dogrib), Tinde’e in Wıìlıìdeh Yatii / Tetsǫ́t’ıné Yatıé (Dogrib / Chipewyan), Tu Nedhé in Dëne Sųłıné Yatıé (Chi ...
in Canada. Mount Mazama formed as a group of overlapping volcanic edifices such as
shield volcano 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 (low viscosity) lava, which travels farther and forms thinner flows than the more vi ...
es and small composite cones, becoming active intermittently until its climactic eruption 7,700 years ago. This eruption, the largest known within the Cascade Volcanic Arc in a million years, destroyed Mazama's summit, reducing its approximate height by about . Much of the edifice fell into the volcano's partially emptied neck and
magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it up ...
, creating a caldera. The region's volcanic activity results from the subduction of the offshore
oceanic plate Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic c ...
, and is influenced by local extensional faulting. Mazama is dormant, but the
US Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...
says eruptions on a smaller scale are likely, which would pose a threat to its surroundings. Native Americans have inhabited the area around Mazama and Crater Lake for at least 10,000 years and the volcano plays an important role in local folklore. European-American settlers first reached the region in the mid-19th century. Since the late 19th century, the area has been extensively studied by scientists for its geological phenomena and more recently for its potential sources of
geothermal energy Geothermal energy is the thermal energy in the Earth's crust which originates from the formation of the planet and from radioactive decay of materials in currently uncertain but possibly roughly equal proportions. The high temperature and pr ...
. Crater Lake and Mazama's remnants sustain diverse ecosystems, which are closely monitored by the
National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational properti ...
because of their remoteness and ecological importance. Recreational activities including
hiking Hiking is a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century.AMATO, JOSEPH A. "Mind over Foot: Romantic Walking and Rambling." In ''On Foot: A Histor ...
,
biking Cycling, also, when on a two-wheeled bicycle, called bicycling or biking, is the use of cycles for transport, recreation, exercise or sport. People engaged in cycling are referred to as "cyclists", "bicyclists", or "bikers". Apart from two ...
,
snowshoeing Snowshoes are specialized outdoor gear for walking over snow. Their large footprint spreads the user's weight out and allows them to travel largely on top of rather than through snow. Adjustable bindings attach them to appropriate winter footwe ...
, fishing, and
cross-country skiing Cross-country skiing is a form of skiing where skiers rely on their own locomotion to move across snow-covered terrain, rather than using ski lifts or other forms of assistance. Cross-country skiing is widely practiced as a sport and recreatio ...
are available, and during the summer, campgrounds and lodges at Crater Lake are open to visitors.


Geography

Mount Mazama is in Klamath County, within the U.S. state of Oregon, north of the border with
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
. It lies in the southern portion of the Cascade Range. Crater Lake sits partly inside the volcano's caldera, with a depth of ; it is the deepest body of freshwater in the United States and the second deepest in North America after
Great Slave Lake Great Slave Lake (french: Grand lac des Esclaves), known traditionally as Tıdeè in Tłı̨chǫ Yatıì (Dogrib), Tinde’e in Wıìlıìdeh Yatii / Tetsǫ́t’ıné Yatıé (Dogrib / Chipewyan), Tu Nedhé in Dëne Sųłıné Yatıé (Chi ...
in Canada. Before its caldera-forming eruption, Mazama stood at an elevation between , placing it about above the lake; this would have made it Oregon's highest peak. The
Global Volcanism Program The Smithsonian Institution's Global Volcanism Program (GVP) documents Earth's volcanoes and their eruptive history over the past 10,000 years. The mission of the GVP is to document, understand, and disseminate information about global volcanic a ...
currently lists its elevation at .


Crater Lake National Park

Crater Lake National Park covers an area of , including forest areas, alpine terrain, the Crater Lake, and the vast majority of Mount Mazama. A
wilderness area Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally re ...
, it was dedicated in 1902 and is overseen by the
National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational properti ...
. It receives about 500,000 visitors each year, and these tourists can go hiking, take bike, ranger-guided, and trolley tours, swim, fish, camp, and participate in other recreational activities. While the Park area remains open throughout the year, certain roads and facilities close in the winter season.


Physical geography

There was frequent
glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such a ...
formation on the mountain as Mazama developed. They carved trenches in the flanks of the volcano in addition to U-shaped valleys under the base of the volcanic cone. These can be seen at three large glacial canyons on its southern slopes: Kerr Notch, Munson Valley, and Sun Notch. Whenever eruptions took place in the presence of ice, lava was chilled by glaciers, creating
glassy Glassy is an adjective meaning, of or resembling glass. Glassy may also mean: * Glassy, amorphous metal * ''Glassy'', a 2021 single album, or the title song by Jo Yu-ri * Glassy phase, amorphous solid * Glassy water, amorphous ice * Glassy carbon, ...
talus deposits. Sometimes, the lava coursed into areas previously carved by glaciers like at Sentinel Rock, filling canyons with volcanic rock.
Moraine A moraine is any accumulation of unconsolidated debris ( regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice sh ...
s occur up to from the rim of Mazama's caldera, and there are glacial striations visible at several sites in the area. When the climactic eruption occurred, the climate was warm and dry, and the most recent period of glacial advance ceased about 27,000 years ago, so by the time Mazama collapsed, ice was likely only present at higher elevations. Using argon geochronology and paleoclimatic records, scientists have identified that the Sand Creek, Sun Creek, and Annie Creek canyons were carved by the advance of ice over lava flows, pushing debris towards Klamath Marsh and Klamath Graben or nearby rivers. A glacial
cirque A (; from the Latin word ') is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic , meaning a pot or cauldron) and (; ). A cirque may also be a similarly shaped landf ...
can be seen on Mount Scott's northwestern flank, and glacial
till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
occurs on Mazama's slopes, especially on the western slopes and at lower elevations. Till and
fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...
sediments occur in the caldera walls, forming particularly thick deposits under Roundtop and Wineglass. Many
lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...
s that were glaciated have since been covered by more recent lava flows. Crater Lake formed from a network of lakes and ponds, eventually reaching a depth of . Lake levels rose while the
Wizard Island Wizard Island is a volcanic cinder cone which forms an island at the west end of Crater Lake in Crater Lake National Park, Oregon. The top of the island reaches above sea level, about above the average surface of the lake. The cone is capp ...
landform inside the crater was forming. Water interacted with lava flows to form pillow lava. Because of climate change patterns over time, Crater Lake's surface level has changed, dropping as much as for example at the beginning of the 20th century. The water from precipitation nearly equals water lost to evaporation and drainage, most leakage taking place at the Wineglass deposit at the northern side of the crater, without which the lake would likely have overflowed at the northern side. Average snowfall in the Crater Lake area has been decreasing since the 1930s. Crater Lake's mean surface water temperatures have increased about since the 1960s. Though this may eventually cause
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...
to grow and obscure the water, Crater Lake remains one of the cleanest bodies of water in the world.


Ecology

Crater Lake National Park and the area surrounding Mount Mazama range in elevation from , providing diverse habitats. In the Cascades, the topography and elevation have influenced local climate patterns, also shaping global climate when volcanic gas and dust have been released into the atmosphere. The southern region of the park supports
ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the ...
forests, and for elevations from , mixed coniferous, fir, and hemlock forests are common. Subalpine zones occur above , often featuring
whitebark pine ''Pinus albicaulis'', known by the common names whitebark pine, white bark pine, white pine, pitch pine, scrub pine, and creeping pine, is a conifer tree native to the mountains of the western United States and Canada, specifically subalpine ...
. Ecological disturbances tend to cause decreasing damage with increasing distance from the source, but volcanic eruptions can lead to more uniform patterns of disruption for their surrounding landscapes. The immediate surroundings of Mazama continue to recover from the eruption. There are more than 50 mammal species in Crater Lake National Park. Opossum species such as the
Virginia opossum The Virginia opossum (''Didelphis virginiana''), also known as the North American opossum, is the only opossum living north of Mexico, its range extending south into Central America. It is the northernmost marsupial in the world. In the United S ...
can be found infrequently, while shrew and mole species in the park area include marsh shrews, Pacific shrews,
American water shrew The American water shrew (''Sorex palustris'') or northern water shrew, is a shrew found in the nearctic faunal region located throughout the mountain ranges of the northern United States and in Canada and Alaska. The organism resides in semi-aq ...
s, fog shrews,
Trowbridge's shrew Trowbridge's shrew (''Sorex trowbridgii'') is a species of mammal in the family Soricidae. It is found in southern British Columbia in Canada and in Washington, Oregon, and California in the United States. Taxonomy Trowbridge's shrew was f ...
s, vagrant shrews, American shrew moles, and
broad-footed mole The broad-footed mole (''Scapanus latimanus'') was a former mole species that has since been split into three distinct species in the genus ''Scapanus'': * Northern broad-footed mole, ''Scapanus latimanus'', ranging from southern Oregon to central ...
s. Bats frequently sighted within the park area include the little brown bat,
hoary bat The hoary bat (''Lasiurus cinereus'') is a species of bat in the vesper bat family, Vespertilionidae. It lives throughout most of North America (possibly including Hawaii, although this is disputed). Taxonomy The hoary bat was described as a ...
, and big brown bat, while the California myotis, silver-haired bat,
Yuma myotis The Yuma myotis (''Myotis yumanensis'') is a species of vesper bat native to western North America. Description The Yuma myotis is a relatively small myotis, measuring in head-body length, with an average wingspan of and a weight of about . T ...
,
long-eared myotis The long-eared myotis (''Myotis evotis'') is a species of vesper bat in the suborder Microchiroptera. It can be found in western Canada, the western United States, and Baja California in Mexico Mexico ( Spanish: México), officially the U ...
,
long-legged myotis The long-legged myotis (''Myotis volans'') is a species of vesper bat that can be found in western Canada, Mexico, and the western United States. Description ''Myotis volans'' is a species of bat found in Order Chiroptera, Family Vespertillio ...
, and pallid bat are more rare. There are populations of American pikas, snowshoe hares, and white-tailed jackrabbits in the region, as well as many rodent species. Chipmunks like
yellow-pine chipmunk The yellow-pine chipmunk (''Neotamias amoenus'') is a species of order Rodentia in the family Sciuridae. It is found in western North America: parts of Canada and the United States. These chipmunks are normally found in brush-covered areas, and ...
s, least chipmunks,
Siskiyou chipmunk The Siskiyou chipmunk (''Neotamias siskiyou'') is a species of rodent in the family Sciuridae. It is endemic to northern California and central Oregon in the United States. Anatomy and morphology The Siskiyou chipmunk is closest in appearance ...
s, and Townsend's chipmunks can be seen, along with various beaver species including
mountain beaver The mountain beaver (''Aplodontia rufa'')Other names include mountain boomer, ground bear, giant mole, gehalis, lesser sasquatch, sewellel, suwellel, showhurll, showtl, and showte, as well as a number of Chinookan and other Native American terms ...
s and
North American beaver The North American beaver (''Castor canadensis'') is one of two extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and introduced in South America ( Patagonia) and Europe (primarily Finland ...
s. The mammals of the National Park area also include various species of squirrel, mice,
vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...
, and gophers, as well as
yellow-bellied marmot The yellow-bellied marmot (''Marmota flaviventris''), also known as the rock chuck, is a large, stout-bodied ground squirrel in the marmot genus. It is one of fourteen species of marmots, and is native to mountainous regions of southwestern Ca ...
s and North American porcupines.
Carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...
mammals consist of
coyote The coyote (''Canis latrans'') is a species of canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological nich ...
s,
red fox The red fox (''Vulpes vulpes'') is the largest of the true foxes and one of the most widely distributed members of the Order (biology), order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe ...
es,
gray fox The gray fox (''Urocyon cinereoargenteus''), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener, the diminutive island fox (''Urocyon littor ...
es,
American black bear The American black bear (''Ursus americanus''), also called simply a black bear or sometimes a baribal, is a medium-sized bear endemic to North America. It is the continent's smallest and most widely distributed bear species. American black bear ...
s,
raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of ...
s,
marten A marten is a weasel-like mammal in the genus ''Martes'' within the subfamily Guloninae, in the family Mustelidae. They have bushy tails and large paws with partially retractile claws. The fur varies from yellowish to dark brown, depending on ...
s, fishers, ermines, long-tailed weasels,
mink Mink are dark-colored, semiaquatic, carnivorous mammals of the genera '' Neogale'' and '' Mustela'' and part of the family Mustelidae, which also includes weasels, otters, and ferrets. There are two extant species referred to as "mink": ...
s,
wolverine The wolverine (), (''Gulo gulo''; ''Gulo'' is Latin for " glutton"), also referred to as the glutton, carcajou, or quickhatch (from East Cree, ''kwiihkwahaacheew''), is the largest land-dwelling species of the family Mustelidae. It is a musc ...
s,
American badger The American badger (''Taxidea taxus'') is a North American badger similar in appearance to the European badger, although not closely related. It is found in the western, central, and northeastern United States, northern Mexico, and south-ce ...
s, western spotted skunks,
striped skunk The striped skunk (''Mephitis mephitis'') is a skunk of the genus '' Mephitis'' that occurs across much of North America, including southern Canada, the United States, and northern Mexico. It is currently listed as least concern by the IUCN on a ...
s,
North American river otter The North American river otter (''Lontra canadensis''), also known as the northern river otter and river otter, is a semiaquatic mammal that only lives on the North American continent, along its waterways and coasts. An adult North American rive ...
s,
cougar The cougar (''Puma concolor'') is a large cat native to the Americas. Its range spans from the Canadian Yukon to the southern Andes in South America and is the most widespread of any large wild terrestrial mammal in the Western Hemisphere. ...
s, and
lynx A lynx is a type of wild cat. Lynx may also refer to: Astronomy * Lynx (constellation) * Lynx (Chinese astronomy) * Lynx X-ray Observatory, a NASA-funded mission concept for a next-generation X-ray space observatory Places Canada * Lynx, ...
es such as
bobcat The bobcat (''Lynx rufus''), also known as the red lynx, is a medium-sized cat native to North America. It ranges from southern Canada through most of the contiguous United States to Oaxaca in Mexico. It is listed as Least Concern on the ...
s. Elk,
mule deer The mule deer (''Odocoileus hemionus'') is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. Two subspecies of mule deer are grouped into the black-tailed deer. Unlike the related whi ...
, and pronghorns can also be found, though more frequently during the summer season. Bird species in the Crater Lake National Park area include various biological families. Common bird species include
hairy woodpecker The hairy woodpecker (''Leuconotopicus villosus'') is a medium-sized woodpecker that is found over a large area of North America. It is approximately in length with a wingspan. With an estimated population in 2020 of almost nine million individ ...
s, great horned owls, blue grouse,
common raven The common raven (''Corvus corax'') is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the Northern Hemisphere. It is a raven known by many names at the subspecies level; there are at least ...
s, dark-eyed juncos, mountain chickadees, red-breasted nuthatches, brown creepers,
Clark's nutcracker Clark's nutcracker (''Nucifraga columbiana''), sometimes referred to as Clark's crow or woodpecker crow, is a passerine bird in the family Corvidae, native to the mountains of western North America. The nutcracker is an omnivore, but subsists mai ...
s, and
Canada jay The Canada jay (''Perisoreus canadensis''), also known as the gray jay, grey jay, camp robber, or whisky jack, is a passerine bird of the family Corvidae. It is found in boreal forests of North America north to the tree line, and in the Ro ...
s, which are visible throughout the year; American kestrels,
northern flicker The northern flicker or common flicker (''Colaptes auratus'') is a medium-sized bird of the woodpecker family. It is native to most of North America, parts of Central America, Cuba, and the Cayman Islands, and is one of the few woodpecker spec ...
s, golden-crowned kinglets,
Cordilleran flycatcher The Cordilleran flycatcher (''Empidonax occidentalis'') is a small insect-eating bird. It is a small ''Empidonax'' flycatcher, with typical length ranging from 13 to 17 cm. Adults have olive-gray upperparts, darker on the wings and tail, w ...
s,
Steller's jay Steller's jay (''Cyanocitta stelleri'') is a bird native to western North America and the mountains of Central America, closely related to the blue jay found in eastern North America. It is also known as the long-crested jay, mountain jay, and p ...
s, western tanagers,
Swainson's thrush Swainson's thrush (''Catharus ustulatus''), also called olive-backed thrush and russet-backed thrush, is a medium-sized thrush. It is a member of genus ''Catharus'' and is typical of it in terms of its subdued coloration and beautiful, ascending ...
es,
hermit thrush The hermit thrush (''Catharus guttatus'') is a medium-sized North American thrush. It is not very closely related to the other North American migrant species of ''Catharus'', but rather to the Mexican russet nightingale-thrush. The specific na ...
es,
American robin The American robin (''Turdus migratorius'') is a migratory bird of the true thrush genus and Turdidae, the wider thrush family. It is named after the European robin because of its reddish-orange breast, though the two species are not closely ...
s, and
rufous hummingbird The rufous hummingbird (''Selasphorus rufus'') is a small hummingbird, about long with a long, straight and slender bill. These birds are known for their extraordinary flight skills, flying during their migratory transits. It is one of nine s ...
s that frequent the area in the summer season; and
mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher ...
and western bluebirds in the fall and summer.
Olive-sided flycatcher The olive-sided flycatcher (''Contopus cooperi'') is a small to medium sized passerine bird in the family Tyrannidae, the Tyrant flycatcher family. It is a migratory species that travels from South to North America to breed during the summer. It ...
s and
chipping sparrow The chipping sparrow (''Spizella passerina'') is a species of New World sparrow, a passerine bird in the family Passerellidae. It is widespread, fairly tame, and common across most of its North American range. There are two subspecies, the eas ...
s are common during the spring and summer seasons, while
yellow-rumped warbler The yellow-rumped warbler (''Setophaga coronata'') is a regular North American bird species that can be commonly observed all across the continent. Its extensive distribution range connects both the Pacific and Atlantic coasts of the U.S. as well ...
s,
pine siskin The pine siskin (''Spinus pinus'') is a North American bird in the finch family. It is a migratory bird with an extremely sporadic winter range. Taxonomy The pine siskin was formally described in 1810 by the American ornithologist Alexande ...
s, and Cassin's finches can frequently be seen during spring, summer, and fall. In the early 20th century, Bull trout were present in many streams and river throughout the National Park area, particularly the Sun Creek and lower Annie Creek areas. Locals began stocking streams with non-native trout populations, forcing Brook trout to compete for resources and leading to their local extinction in Annie Creek, along with a significant decline in Sun Creek by the end of the 1980s. By 1992, Crater Lake National Park initiated a bull trout conservation project, removing invasive fish populations with electrofishing, snorkeling, and introduction of the toxin and inhibitor of cellular respiration antimycin A. They also created small barriers to keep new trout from reaching Sun Creek. In 1999, Bull trout were considered a "threatened" species by the Endangered Species Act, though locally, there are now about 2,000 Bull trout in the stream, almost ten times as many as the low point for Bull trout abundance at just 200 fish. The project now works with the state government to expand Bull trout distributions from Sun Creek into neighboring forests with fish barriers and removal of invasive fish species. Climate change threatens the American pika populations in the Crater Lake area, as they cannot tolerate warm weather because their fur does not release heat efficiently. Climate change might be diminishing their food supply via disturbances of vegetation growth patterns. At least three pika populations in Oregon have disappeared within the past few decades. Likewise, as a result of climate change, mountain pine beetle infestations have become more frequent among Whitebark pines on the rim of Crater Lake and present on nearby peaks. The National Park Service estimates that roughly half of the whitebark pines in Crater Lake National Park have died or are dying. Because the ecosystem in Crater Lake is isolated from the regional area, it holds particular interest from ecologists, so the United States National Park Service closely monitors human and natural changes to the lake environment.


Human history

The Klamath Native Americans of the area believed that Mount Mazama was inhabited by Llao, their "Chief of the Below World." After the mountain destroyed itself the Klamaths recounted the events as a great battle between Llao and his rival Skell, their sky god, or "Chief of the Above World." Though the narrative has several slightly different iterations, commonly the legend goes that Llao saw a beautiful Klamath woman, the daughter of a chief, and became angry when she refused his offer of immortality if she would be his consort. Furious, Llao emerged from Mazama and threw fire upon the people beneath the mountain, and Skell stood on
Mount Shasta Mount Shasta ( Shasta: ''Waka-nunee-Tuki-wuki''; Karuk: ''Úytaahkoo'') is a potentially active volcano at the southern end of the Cascade Range in Siskiyou County, California. At an elevation of , it is the second-highest peak in the Cascad ...
, trying to defend the people against Llao's fury. As the earth shook and volcanic rock fell from the sky, two holy men sacrificed themselves to Mount Mazama's crater, and Skell was able to force Llao back into the volcano, which then collapsed on top of him; other accounts tell that Skell smashed the peak on top of Llao. Torrential rain followed, filling in the hole left by Mazama's collapse to form Crater Lake. Native American people have lived in the area near Mazama for at least 10,000 years. At least part of the surrounding vicinity was occupied by indigenous populations when Mazama resumed activity about 8,000 years ago, following about 20,000 years of dormancy. Most evidence suggests that Mazama served as a camp site, but not a permanent place of habitation. Sagebrush sandals have been discovered to the east of the mountain. These populations faced an increasingly dry climate and the hazards associated with volcanic activity. In civilizations south of Mazama, stories about the volcano's eruption have been transmitted for many generations. Native populations did not tell settlers about the area because it held sacred importance among tribes throughout Oregon and northern California.
Shamans Shamanism is a religious practice that involves a practitioner (shaman) interacting with what they believe to be a spirit world through altered states of consciousness, such as trance. The goal of this is usually to direct spirits or spirit ...
did not allow local Native Americans to look towards Crater Lake, and the Klamath people believed that just looking at Mazama would cause death. Though there are no tribal legends surrounding Crater Lake, some Native Americans still refuse to look at the water. During the 19th century, one Klamath leader named Lalek predicted scientific discoveries that described Mount Mazama's destruction, claiming that it had collapsed as a result of a particularly violent eruption. Geologists had not discovered this mechanism for caldera formation yet, but the hypothesis was recorded by the soldier William M. Colvig in 1865, and then reprinted in Ella Clark's ''Indian Legends of the Pacific Northwest''. The last major volcanic landform in the Cascade Range identified by white settlers, Mazama was first visited by non-indigenous people in the spring of 1853. Eleven miners from
Yreka, California Yreka ( ) is the county seat of Siskiyou County, California, United States, near the Shasta River; the city has an area of about , most of it land. As of the 2020 United States Census, the population was 7,807, reflecting a meager increase fr ...
, stopped at a mercantile store in
Jacksonville, Oregon Jacksonville is a city in Jackson County, Oregon, United States, approximately west of Medford. It was named for Jackson Creek, which flows through the community and was the site of one of the first placer gold claims in the area. It includes ...
, owned by Isaac Skeeters, boasting that they knew where to find a gold mine called "Lost Cabin." Financed by a successful gold miner named John Wesley Hillman, Skeeters led a team with ten other Oregonians to find the mine. On June 12, they reached Crater Lake, which Skeeters noted had the bluest water he had ever seen, suggesting they name it "Deep Blue Lake." Though their trip failed to procure gold before running low on provisions, they returned with the discovery of the lake, though it was forgotten amidst the absence of gold in that region. By 1862, a separate group of Oregon prospectors led by Chauncey Nye reached the Crater Lake area. Nye authored an article for the Jacksonville ''Oregon Sentinel'' in which he wrote that he had named the depression Blue Lake for its color, the first published description of the lake. Fort Klamath was established in 1863, to the southeast of the current boundaries of the National Park area. A wagon road was built to the Fort from the Rogue River Valley as a result. On August 1, 1865, the lake was encountered by hunters on the road, and a party of soldiers and civilians went to see the lake after hearing of their observations. Sergeant Orsen Stearns climbed down into the caldera, followed shortly after by Captain F. B. Sprague, who thought they should name the lake "Lake Majesty." The newspaper editor Jim Sutton and a group of people visited Crater Lake in August 1869, using a boat to reach Wizard Island and publishing an article about their experience in the Jacksonville newspaper. Sutton suggested the new name of "Crater Lake". Mount Mazama received its English name in 1896 from William G. Steel, the founder of the climbing club The Mazamas, which formed at
Mount Hood Mount Hood is a potentially active stratovolcano in the Cascade Volcanic Arc. It was formed by a subduction zone on the Pacific coast and rests in the Pacific Northwest region of the United States. It is located about east-southeast of Portl ...
in 1894. The word comes from a Native American word meaning "mountain goat", derived from an Aztec term to refer to "small deer." Steel gave
United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
geologist Joseph S. Diller the idea for Mazama's name to help promote national park status for the vicinity by using his organization as the inspiration for the mountain's name. Crater Lake is called ''Giiwas'' in the Klamath language. Steel had helped map Crater Lake in 1886 with Clarence Dutton of the United States Geological Survey. The conservation movement in the United States was gaining traction, so Steel's efforts to preserve the Mazama area were achieved on two scales, first with the creation of the local Cascade Range Forest Reserve in 1893, and then on May 22, 1902 with the recognition of Crater Lake National Park. A few decades after its discovery, Mazama began attracting geological interest. After conducting research at Mazama during the 1880s, in 1902, Joseph S. Diller published a major report with the United States Geological Survey concerning Crater Lake National Park. In the study, he and co-author Horace B. Patton made the claim that Mazama had collapsed instead of being blown apart, the first American geologists to do so. Their work was followed by research led by
Howel Williams Howel Williams (October 12, 1898 – January 12, 1980) was a noted American geologist and volcanologist. Early life He was born of Welsh parents in Liverpool, England, on October 12, 1898. He received a BA in geography in 1923 and an MA in ar ...
of the
University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant un ...
, which was published in 1942. In the paper, Williams mapped the volcano's
dacite 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 rhyo ...
and andesite lava flow deposits. During the 1980s, Charles Bacon and other United States Geological Survey geologists expanded on Williams's work, determining more specific details about its caldera formation.


Geothermal energy

Studies of heat flow and the water chemistry in Crater Lake and the alteration of rocks older than 120,000 years ago suggest that
hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...
areas exist in the Mazama vicinity. Most springs show similar chemistry, from the weathering of volcanic glass and clinopyroxene. These features probably formed due to processes related to residual heat from the magma chamber that produced the climactic Mazama eruption 7,700 years ago. The lake shows convective mixing that cycles every three years as thermal fluid moves into the lake through its floor, creating thermal springs that formed silica spires with heights up to . As a result, the California Energy Company drilled two geothermal exploration wells: the MZI-11A with a depth of to the east of the national park barrier at the Scott Creek Drainage, and the MZII-1 with a depth of to the south of the same boundary and to the east of Annie Creek. The maximum temperature they have observed at the southern well is , while the maximum temperature was at the eastern well. The convective heat discharge in Crater Lake marks the third largest in the Cascades, after the Austin Hot Springs and at
Lassen Volcanic National Park 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 Vol ...
. Scientists from the United States Geological Survey think that sources for geothermal energy use exist at Mazama and Crater Lake.


Geology

Produced by the subduction of the Juan de Fuca tectonic plate, which moves slowly in a northeastward direction with the Gorda tectonic plate under the North American tectonic plate, Mazama is part of the Cascade Volcanic Arc that stretches from northern California to southern British Columbia. Mazama sits within a region of
crustal extension Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body's crust or lithosphere. Deformation styles The types of structure and the geometries formed depend on ...
marked by fault zones, including north–south-trending normal faults such as the Annie Spring fault within the West Klamath Lake fault zone, which might produce damaging earthquakes. Likewise, the Red Cone Spring fault cuts through
basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Am ...
deposits at Red Cone from 35,000 years ago; together, the two faults move at an average rate of each year. There do not appear to be faults present in the Crater Lake caldera wall, but the volcano induced a stress field in the upper crust nearby. Mazama is underlain by the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...
High Cascade
basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
and
mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks in ...
(rich in magnesium and iron)
andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predo ...
to the west and southwest, with high-volume
rhyodacite Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from ra ...
lava flows from 600,000 to 700,000 years old underlying Mazama deposits to the south, southeast, east, and northeast. It is a major Cascade volcano, and is at the intersection of the Cascade Range and Klamath graben, the north–northwest trending basin also surrounded by fault zones. The
Basin and Range Province The Basin and Range Province is a vast physiographic region covering much of the inland Western United States and northwestern Mexico. It is defined by unique basin and range topography, characterized by abrupt changes in elevation, alternating ...
lies to the east. Mazama lies within the broad segment of the Cascades arc, where smaller volcanoes are common because of melting patterns of the Earth's mantle within the region. Erupting magma that ranged from high-alumina olivine
tholeiite The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma ...
to magnesian basaltic andesite, these volcanoes show increased contents of
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...
-produced or melted fluids that mixed with another magma chamber in the mantle. These magmas vary from 47.6 percent to 73.2 percent
silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
. Mazama and Crater Lake form part of the Mazama reach of the Oregon Cascades, which stretches for from Timber Crater to the Big Bunchgrass shield volcano. This includes 175 Quaternary volcanic vents within a belt that ranges from in width, which has a high vent density with many shields and monogenetic volcanic centers. After Newberry Volcano, Mazama is the second largest Quaternary volcanic edifice in Oregon, and the most voluminous, with an overall volume of . Mazama is the newest of the Quaternary calderas in the Cascade Volcanic Arc, which also include the Newberry calderas and the caldera at the
Medicine Lake Volcano Medicine Lake Volcano is a large shield volcano in northeastern California about 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 Ra ...
. Quaternary monogenetic volcanism throughout Oregon's High Cascades includes cinder cones,
lava field Lava fields are large, mostly flat areas of surface or subaquatic lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or hundreds of miles across the underlying terrain. Morphology and str ...
s, and small shield volcanoes, which have produced lava ranging from low-potassium, high-alumina olivine tholeiite to medium-potassium calc-alkaline basalt, basaltic andesite to shoshonitic basaltic andesite. The Mazama volcanic complex originally formed as a cluster of overlapping edifices. Made up of shield volcanoes and small stratocones, it had an irregular shape. Mount Scott, at a height of , marks the oldest visible remnant of this original cluster. Scott was the first of the composite volcanoes that created the Mazama complex, formed by a quick and active cone-building phase and becoming inactive long before the most recent eruption at Mazama. With time, eruptive activity moved to the west, creating the Applegate Peak and Garfield Peak cones on the southern flanks of the volcanic center. Hawaiian eruptions from neighboring shield volcanoes also built up Mazama, producing basaltic andesite lava flows that ranged from on average in thickness. These flows, present on the southern, western, and eastern walls of Mazama's caldera, also contained
lava bombs A volcanic bomb or lava bomb is a mass of partially molten rock (tephra) larger than 64 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. Because volcanic bombs cool after the ...
. Viscous eruptions of andesitic lava that reached thicknesses of several hundred feet further built up Mazama's cones, creating a solid, dense interior rich with angular lava blocks. Research by Howel Williams superimposed the Crater Lake caldera on other Cascade stratovolcanoes including
Mount Shasta Mount Shasta ( Shasta: ''Waka-nunee-Tuki-wuki''; Karuk: ''Úytaahkoo'') is a potentially active volcano at the southern end of the Cascade Range in Siskiyou County, California. At an elevation of , it is the second-highest peak in the Cascad ...
in California and
Mount Rainier Mount Rainier (), indigenously known as Tahoma, Tacoma, Tacobet, or təqʷubəʔ, is a large active stratovolcano in the Cascade Range of the Pacific Northwest, located in Mount Rainier National Park about south-southeast of Seattle. With a ...
in Washington state, and concluded that Mazama stood at pre-collapse, which has been accepted as the standard estimate by geologists. By the Holocene, the Mazama volcano was made up of several, clustered peaks with Mount Scott on the eastern end and Hillman Peak on the far west side. The volcanoes likely rose in elevation from east to west, and they also featured volcanic cones and lava domes on their southern flanks. Glacial horns like the Watchman lava flow were also present, and the mountain may or may not have sustained glaciers close to the summit. At the time of its collapse, Mount Mazama encompassed an area of and represented one of the major volcanoes in the High Cascades branch of the greater Cascade Range. It was the largest volcanic edifice between Mount Shasta in California and the Three Sisters complex in Oregon. Before the eruption, it had been significantly altered by glacial erosion, which carved U-shaped valleys on its southern and southeastern slopes. The northern and western sides of the caldera do not show prominent evidence of glacial erosion, since they feature lava flows that only underwent alteration by late
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
epoch glacial motion. Outside of the caldera, most hills show evidence of glacial alteration except those from the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
epoch and low elevation landforms including Pleistocene lava domes and cinder cones. Mount Scott has also been heavily eroded by ice, and the Union Peak volcano now consists only of a pyramidal horn. Though it now has dimensions of and a width of , scientists think the original collapse diameter was . It now includes several small lava domes and cinder cones, including Wizard Island and the underwater volcano Merriam Cone. The highest elevation in the Mazama Complex is now Mount Scott, at an elevation of , with a relief of above Crater Lake's surface waters. Except for the tallest slopes of the complex, all cones have been covered with deposits from the climactic eruption at Mazama 7,700 years ago. Scientists now use the exposed contents of the caldera rim wall to investigate eruptions and mapping the eruptive history of the region. Throughout its known eruptions, Mazama has produced 43 percent rhyodacite, 42 percent andesite, 15 percent dacite, and less than 1 percent basaltic andesite. All of the rhyodacite has been produced within the past 30,000 years of activity, suggesting that regional and local distribution of compositions were not uniform over time. Andesite and dacite lava flows from the volcano usually have
plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more p ...
as their major phenocryst, though augite and hypersthene are also present, the latter more abundant. Olivine form minor phenocrysts, which are found throughout lava flows from Mazama, and hornblende can be found in some andesite lava flows. Basalt and mafic andesite lava flows from Mazama and nearby eruptive vents have relatively higher amounts of olivine and lack hypersthene, and the mafic andesite deposits display textures that indicate they underwent greater mixing than andesite and dacite deposits.


Mazama Ash

In the western United States and Canada, volcanic ash often forms distinct layers among recent geological deposits, which can be used for
stratigraphy Stratigraphy is a branch of geology concerned with the study of rock layers ( strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...
among geologists and
archaeologists Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscapes ...
. Given the large distribution of the historic eruption of Mount Mazama, Mazama Ash serves as a common geological marker. Mazama Ash had a minimum fallout area of , while ash from northwestern Washington's Glacier Peak volcano, known as Glacier Peak Ash, encompassed an area of more than . Mazama Ash is found at a higher layer than the Glacier Peak ash, estimated to have deposited over 13,000 years ago. Mazama Ash is the most widely distributed
tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they r ...
layer from the late Quaternary in the United States and southwestern Canada, extending to eight states to the west and three Canadian provinces. Mazama Ash forms orange colored deposits. Like the Glacier Peak Ash deposits, Mazama Ash is well preserved in the Pacific Northwest. It is distinguishable from the lump pumice deposits ejected from the Glacier Peak volcano, which contain more
phenocryst 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...
s. Mazama Ash also has more soda,
yttrium Yttrium is a chemical element with the symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a " rare-earth element". Yttrium is almost always found in co ...
, ytterbium, and
zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'' ...
, and less silica and lime than eruptive products from Glacier Peak, and it forms finer deposits than Glacier Peak Ash. With an age between 6,000 and 7,000 years, Mazama Ash corresponds to the estimated time for Mazama's climactic eruption 6,600 years ago, identified by
radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was de ...
of wood charred by ashflows. Some of the Glacier Peak ash has been found in strata beneath Mazama Ash in Washington state and in eastern
Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...
, to the southeast of Glacier Peak. Studies of Glacier Peak Ash deposits suggest that they are older than Mazama Ash, at about 12,000 years old. Glacier Peak Ash has not been found in deposits less than 10,000 years old, and nearly all human artifacts have been found above its deposits, except for a site at Birch Creek where non-diagnostic artifacts were discovered beneath Glacier Peak Ash.


Subfeatures

Formed of a complex of stratovolcanoes and shield volcanoes, there are about 35 known satellite vents in the Mazama complex. Mazama is surrounded by monogenetic cinder cones, lava fields, and shield volcanoes made up of calc-alkaline basalt and andesite,
tholeiite The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma ...
, and shoshonitic andesite. Varying in age from 600,000 to 40,000 years old, these edifices closely resemble other monogenetic volcanoes in the High Cascades. Extending from the eastern half of Mazama and to the southeast lies a volcanic field consisting of
rhyodacitic Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from rapid ...
lava domes and lava flows between 700,000 and 600,000 years old, which encompasses an area of more than . This large field is underlain by rhyodacite in its southeastern segment, and is cut by north–south trending normal faults. Moving from west to northwest, Mazama stratovolcanoes and shield volcanoes grow progressively younger. The oldest, at 400,000 years old, occur at Phantom Ship and Mount Scott, while the youngest can be found at the Hillman Peak stratovolcano, dated to 70,000 years old. There are also andesite flows at the northern rim of Mazama dated to between 50,000 and 40,000 years old. Shield volcanoes near Mazama feature lava flows made of agglutinated mafic andesite, which form sheets about thick, as well as more deposits from more viscous andesite and dacite magma that reach thicknesses up to . Many of these deposits (both dacitic and andesitic) contain undercooled, crystal-poor segments of andesite, including at Mount Scott and Phantom Cone. Lava and ice interactions are suggested by exposures of glassy
breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of ...
in Mazama's caldera, as well as lava flows covering glaciated lava deposits. About 70,000 years ago, several
silicic Silicic is an adjective to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent. Granite and rhyolite are the most common silicic rocks. Silicic is the grou ...
(rich in silicon dioxide), explosive eruptions occurred, including a significant event at Pumice Castle on the eastern wall of Mazama. This formed welded deposits near the vent, also forming non-welded deposits to the south and on the northern part of Mazama. Between 40,000 years ago and Mazama's major eruption, no andesitic or dacitic volcanism took place. However, rhyodacitic magma was erupted at Grouse Hill, Steel Bay, and Redcloud Cliff in the form of pumice and lava flows made of
hornblende Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rock ...
-
phyric 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...
, or chemically evolved, rhyodacite. During this period of the late Pleistocene or early Holocene, lava domes such as those at Sharp Peak, Grouse Hill, and Merriam Point formed, sharing chemical compositions, with silica contents at about 70%.
Pyroclastic Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...
cones at Mazama include Wizard Island, Bald Crater, Maklaks Crater (also known as Diller Cone) and Forgotten Cone. In addition to its crater, referred to as Williams Crater or the Forgotten Crater, Mazama's various volcanic vents occur at Cleetwood, Llao Rock, and Redcloud, which are at elevations of , , and , respectively. Nearby cinder cones include Bear Butte, Crater Peak, Desert Cone, Lookout Butte, Pothole Butte, Red Cone, Scout Hill, and Union Peak. There are at least 13 cinder cones within Crater Lake National Park, and at least eleven more in the nearby area. They were fed by a different magma chamber than Mazama, though they likely received magma from basaltic andesite reservoirs in the vicinity. The exception is Williams crater, which erupted basalt and dacite and got silicic lava from the western part of Mazama's magma chamber. Stratovolcanoes in Mazama's vicinity consist of Sentinel Rock, Mount Scott, Phantom Cone, Dutton Cliff, and Danger Bay. Mazama has a few composite cones in the vicinity of the caldera. At about 420,000 years old, Mount Scott has a conical shape, but has been extensively altered by Pleistocene glacial erosion, which carved a large cirque on its western flank and smaller ones on its eastern and northeastern sides. Scott lacks a summit crater. Hillman Peak was the youngest composite cone in the Mazama eruptive center, forming about 70,000 years ago. It lies on the southwestern side of the caldera, and it represents the highest point on the Mazama rim, rising above Crater Lake. The cone was cut down the middle during Mazama's collapse post-eruption, creating a cross-section of its interior composition. Shield volcanoes that contributed to Mazama's growth only erupted for several hundred to several thousand years. They erupted rapidly, spraying fluid lava that included lava bombs and incandescent fragments. Llao shield on the northwestern side of the Mazama complex shows a representative structure for the shields that helped form Mazama.


Eruptive history


Early activity

The Mazama vicinity formed gradually, its earliest deposits consisting of dacite from up to 1.28 million years ago. Between 725,000 and 500,000 years ago, rhyodacite was erupted, eventually forming a lava dome field with a volume of and dimensions of . This featured up to 40 rhyodacitic domes and lava flows, produced between 470,000 and 410,000 years ago before stratocone formation began. Mazama formed as a group of overlapping volcanic edifices, which included shield volcanoes and small composite cones. Cone-building eruptions took place within short periods of time. Shield volcanoes fed Mazama's expansion with basaltic andesite lava flows that covered large expanses on the slopes of the mountain. Forming lava fountains similar to those observed in
Hawaiian eruption A Hawaiian eruption is a type of volcanic eruption where lava flows from the vent in a relatively gentle, low level eruption; it is so named because it is characteristic of Hawaiian volcanoes. Typically they are effusive eruptions, with basaltic ...
s, the shield volcanoes erupted incandescent lava bombs and were deposited on the southern, western, and eastern flanks of the complex. They have average thicknesses of . Roughly 215,000 years ago, another flank vent erupted dacitic lava that coursed to the west for at least , with volcanic
dikes Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes ...
that trend toward the vent still present in the Mazama caldera wall. The complex remained inactive for about 40,000 years before it resumed activity, erupting andesitic lava from another flank vent, building a large shield volcano from 170,000 to 120,000 years ago. Other andesitic lava deposits can be observed in the caldera wall's northern side. The Mazama complex was inactive between 100,000 and 75,000 years ago. About 75,000 years ago, the volcano erupted effusive lava flows of andesite that formed thick deposits below Hillman Peak that extended at least from the caldera rim. Many of the major cone-creating eruptions at Mazama were effusive rather than violently explosive, but explosive eruptions about 70,000 years ago yielded silicic lava that created thick pyroclastic deposits. These deposits include Pumice Castle, an orange edifice at the eastern wall of the caldera, which formed by the fusion of glassy pumice fragments. Similar activity on the northern side of Cloudcap and the eastern segment of Llao Rock that ejected dacitic tephra and pyroclastic rock also formed fused edifices. About 50,000 years ago, a vent at Mazama erupted the Watchman flow, which filled a canyon at the southwestern wall of the complex. From 50,000 to 40,000 years ago, Mazama vents continued to erupt andesite lava flows onto the northern and southwestern slopes and create dacite lava domes on the southern flanks. These domes often collapsed and produced pyroclastic flows that coursed down the southern slope of the volcano, forming deposits up to Devil's Backbone, a craggy volcanic dike that was exhumed when the volcano collapsed. Throughout its eruptive history, Mazama has produced basaltic andesite, andesite, and dacite lava. About 40,000 years ago, it underwent a dramatic shift to solely rhyodacite lava, which was highly viscous and had a silica content at about 70 percent. Between 30,000 and 25,000 years ago, rhyodacitic eruptions occurred at the complex, yielding pumiceous
tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they r ...
and lava flows from Grouse Hill, Steel Bay, and Redcloud Cliff. At Redcloud Cliff, a lava flow formed with glassy columns that touched glaciers, creating a large, inverted stone triangle on the eastern rim of Mazama. These same eruptions formed a nearly vertical-walled crater, producing pumice and creating a dome over the Redcloud vent. Grouse Hill's lava flow deposit and lava dome formed at about the same time, about 27,000 years ago. At the end of this eruptive sequence, rhyodacite lava domes formed on the northeastern slopes of the volcano. Between 100 and 200 years before the climactic eruption, Llao Rock, a thick block of dark lava with a volume of , was produced from a rhyodacite flow erupted from Mazama. It has a round center and extensions on the sides, resembling a bird of prey. The formation of Llao Rock was preceded by explosive eruptions of rhyodacite, creating pumice and ash that were ejected high into the atmosphere and carried for several hundred miles into northern and eastern Washington state, eastern Oregon, and western Nevada. A large crater formed but was filled by subsequent lava flows. Shortly before the major, caldera-forming eruption at Mazama, the Cleetwood flow was produced. Also composed of rhyodacite lava, it originated from a vent on the northern side of the complex eastward of Llao Rock. It likely only occurred weeks or months before the major eruption, as Mazama's collapse formed a backward flow of lava when it cut through the Cleetwood lava, suggesting that the Cleetwood lava was still hot enough to flow and move. Tephra from the last major eruption that was emplaced atop Cleetwood deposits has been altered by heat and gas from the Cleetwood lava. Both these eruptive periods took place on the northern flank of the Mazama complex, not far from the magma chamber that produced the climactic eruption shortly after.


Climactic eruption

Mazama's climactic eruption has been dated to about 6,845 ± 50 years ago via radiocarbon dating, or about 7,700 years ago via
dendrochronology Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atm ...
. Other scientists have determined ages of 6,730 ± 40 years ago or roughly 7,470–7,620 calendar years ago, as well as 7,627 ± 150 calendar years ago. Fallout from the eruption continued for roughly three years, though the major eruption only occurred for a few days. The eruption is thought to have occurred during autumn, as inferred from pollen data. The eruptive activity that led to Mazama's collapse proceeded in two phases. During the first phase, shortly after the eruption of the ''Cleetwood flow'', a vent at a higher elevation on the northern side of the Mazama complex (but still below the summit) produced a high ash column into the
stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air h ...
. Ash extended to eight states in the west and three Canadian provinces. As a result, Mazama Ash has become a commonly used benchmark for measuring the relative age of objects, compared to its orange colored deposits. Pumice deposits reached depths of adjacent to Mazama's base, still reaching thicknesses more than as far as to the northeast. The ejecta featured blocks of medium-grain
granodiorite Granodiorite () is a coarse-grained ( phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from gr ...
, as well as inclusions of
diabase Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...
,
quartz diorite Quartz diorite is an igneous, plutonic ( intrusive) rock, of felsic composition, with phaneritic texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with 10% or less potassium feldspar. Quartz is present at between 5 an ...
,
granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies un ...
, aplite, and granophyre. Ashfall layers have been eroded by pyroclastic flows and with time, but they are still visible at Hillman Peak and along the Cleetwood Trail. The Plinian column from the eruption devastated the area hundreds of miles north and northeast of Mazama, but to the southwest and west, little pumice or ash were deposited. The eruption's character changed dramatically as the column of pumice and ash collapsed. The exact cause is not well understood; it may have been the result of the enormous weight of the tephra or the expansion of the eruptive vent. The sudden deposition of so much pumice generated pyroclastic flows that moved down the northern side of the volcano, coursing west–east from Llao Rock to Redcloud Cliff. The first of these pyroclastic flows were deposited at superheated temperatures, welding fragments and creating the Wineglass welded tuff, which consists of big blocks of orange-brown and gray rock. These emplacements can only be observed on the northern slopes; they are absent from the southern slopes of the volcano. Mazama was covered with incandescent pumice. The extreme weight of eruptive material began to push down on the volcano's summit, similar to a
piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-t ...
. Eventually, the top of Mazama's magma chamber subsided, and concentric openings formed by the summit, producing smaller vents surrounding the main eruptive cone. Pumice ejected from these new fractures created rapid pyroclastic flows that coursed down all the sides of Mazama, traveling over tall ridges and summits of subfeatures and extending tens of miles from their vents. These flows altered the surfaces surrounding Mazama, removing ashfall and then depositing their contents in nearby valleys. Some of the flows traveled more than from their source, destroying
timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, w ...
in their paths, while others deposited their rock into river valleys to the north and west of Mazama, leaving layers of pumice between in thickness. Ash clouds also rose up from the pyroclastic flows. Pyroclastic flows also moved to the east, reaching more than from the base of Mazama. These deposits have diameters between , though they are punctuated by pumice blocks with diameters of that extend as far as from Mazama's summit. Flows containing pumice coursed into the Annie Creek and Sun Creek canyons southward of Mazama, depositing of material, which have still not been fully eroded after almost 8,000 years. To the southeast, pyroclastic flows coursed into Sand Creek and extended more than in that direction, some reaching Klamath Marsh, the Williamson River, and the Klamath Lakes. Mazama's eruptive activity drew from deeper layers of the magma chamber that fed its climactic eruption, with denser layers of andesite and basaltic andesite lying beneath lighter layers of rhyodacite. The last of the pyroclastic flows erupted contained andesitic, gray scoria that was deposited above the pale orange and yellow rhyodacite pumice from earlier phases of the eruption. The final eruptions formed the Pumice Desert, a treeless plain on the northern and northeastern side of Mazama, as well as filling the Pumice Creek valley and parts of the Klamath Marsh. Reaching thicknesses between , the emplacements from these flows yielded fumarolic activity, still detectable in the Annie Creek and Sand Creek canyons. Erosion from rain and stream flow has left pipes from the andesitic lava flows as columns and spires. Before collapse, the Mazama edifice had an estimated volume of , though it may have exceeded taking glacial erosion into account. After the climactic eruption, Mazama's peak was completely destroyed, replaced by a depression with a depth of surrounded by cliffs. The volume of magma erupted from Mazama during this eruption was 14 cubic miles (61 km3). The lava produced was zoned vertically according to arrangement within the source magma chamber, and was calc-alkaline in composition. It consisted of roughly 90 percent uniform rhyodacitic pumice, which contained about 10 percent
phenocryst 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...
s, the rest made up of crystalline andesite scoria and mafic crystals. The total eruptive volume adds up to 42 cubic miles (176 km3) of pumice, ignimbrite, and tephra. The eruption released aerosols that lowered temperatures globally in the Northern Hemisphere, with estimates of for one to three years after the eruption. The temperature changes were possibly greater than the effects of the
1815 eruption of Mount Tambora Mount Tambora is a volcano on the island of Sumbawa in present-day Indonesia, then part of the Dutch East Indies, and its 1815 eruption was the most powerful volcanic eruption in recorded human history. This volcanic explosivity index (V ...
. Mazama's climactic eruption produced stratospheric mass loadings of of
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
, with an estimated minimum
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
degassing of during its eruption. Aerosol from the eruption traveled as far as
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
, falling for as long as six years. The United States Geological Survey has referred to the 7,700 years ago Mazama eruption as the largest explosive eruption within the Cascades in the past million years, however recent studies say that the volume of the Rockland ash, which erupted from the
Lassen Volcanic Center 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 ...
about 600,000 years ago could be upto 326.7 km3. Which would make it over twice the size of the Mazama ash. Mazama's climactic eruption was one of the largest eruptions during the Holocene epoch. Considering Mazama's eruptive output within the past 420,000 years, it may have produced more than of eruptive volume, making it either the third or fourth most productive Quaternary volcanic center in the Cascade Range. The eruption had a Volcanic Explosivity Index of 7, as determined from eruption cloud height, eruptive volume, and qualitative observations.


Recent activity and potential hazards

Since the climactic eruption 7,700 years ago, all eruptive activity at Mazama has occurred within the caldera. After the caldera formed, the original crater was widened by avalanches from the walls. These gave a scalloped profile to the caldera, such as the coves at Llao Bay, Steel Bay, and Grotto Cove. The Chaski slide, for example, the most prominent landslide detectable on the caldera wall, occurred long after the formation of the crater. Located on the southern side, it contains lava blocks between in length, many of which now reside underwater on the floor of Crater Lake. As the crater filled with landslides, lava, and water, the caldera's appearance changed over time. New cones and lava fields have formed inside the caldera, all of which have been submerged except for Wizard Island. Mapping the caldera floor with high-resolution multibeam echo sounders, vehicle-motion sounders and navigators, and a dual-differential global positioning system (DGPS), scientists from the US government and universities detected volcanoes and landslide deposits under the water. Between 7,700 and 7,200 years ago, the central lava platform, the Merriam Cone, and Wizard Island were produced, as well as lava flows. These eruptions produced of andesitic lava, half of that in the Wizard Island cone. Wizard Island lava interacted with water to form breccia piles, and as the water levels rose, only the top of the Wizard Island edifice stayed above the water. The edifice has a lavaberg shape, as it sits above a larger, ovular pedestal rising above the floor of Crater Lake; just two percent of Wizard Island sits above the water surface. At the summit of the above-water cone, a small lava flow from a lava fountain appears, on the southwestern flank. There is also a volcanic plug poking out of the crater floor as a body of dark lava. Lava blocks with diameters of can be seen along the rim of the crater, possibly produced from later stages of cone-building eruptions that created Wizard Island. The central platform was created by a similar vent eastward of Wizard Island, made up of effusive lava that created lava fields northward and eastward of its vent. Merriam Cone does not have a summit crater, but rises to above the northern lake floor. Merriam Cone was produced underwater, and was probably formed at the same or similar time as Wizard Island and the central platform. Mazama was last active about 4,800 years ago, when an eruption took place near Wizard Island's eastern base. This eruption took place underwater, and it produced viscous lava that created a rhyodacite lava dome, about 2,400 years after the first period of postcaldera activity. Given that Mazama has had periods of sporadic eruptions for 420,000 years, the United States Geological Survey thinks that it is "virtually certain" that Mazama will erupt again in the future. Mazama is considered dormant, but it remains monitored by the United States Geological Survey Cascades Volcano Observatory. Future eruptions would likely take place near the western side of the complex and within the caldera rim; they could occur underwater. The ejection of lava rich in gas from shallow water could produce huge ash columns, but submarine eruptions at deeper depths may decrease the explosiveness of the event. Nonetheless, the rapid mixing of water and lava could produce dangerous
pyroclastic surge A pyroclastic surge is a fluidised mass of turbulent gas and rock fragments that is ejected during some volcanic eruptions. It is similar to a pyroclastic flow but it has a lower density or contains a much higher ratio of gas to rock, which makes ...
s, which are more gaseous and less solid than pyroclastic flows. Such flows could pass over topographic barriers, move rock fragments at , and travel several miles from their vent. Mazama is unlikely to produce mudflows far from the caldera, though a nearby vent outside the caldera could erupt and mix with snow. Eruptions are unlikely to produce waves that extend beyond Crater Lake, but powerful explosions could produce tall waves in the caldera. An eruption as explosive as the one 7,700 years ago is unlikely given that it would require larger volumes of magma than are known to be available within the Mazama vicinity. Landslides could flood adjacent shoreline regions, but they are not likely to induce failure of the caldera's walls, as they rise more than above the lake's surface. Earthquakes from the nearby West Klamath Lake fault zone could reach magnitudes up to 7.0 on the
Richter scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...
, but these only occur every 3,000 to 10,000 years; they could generate tall waves by creating landslides. Though local earthquakes from volcanic activity would create motion in the lake, they would likely only reach maximum magnitudes of 5.0 on the Richter scale. Crater Lake is poorly monitored, and not highly active seismically among the Cascade volcanoes. The largest earthquake threat originates from the
Cascadia subduction zone The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is a very long, sloping subduction zone where the Explorer, Juan de Fuc ...
, which could produce earthquakes with a magnitude of 8 or 9 that could lead to huge waves in Crater Lake. Though the population within of Mount Mazama is only about 50 people, more than 270,000 live within of the volcano. Even so, highly consequential eruptions at Mazama seem unlikely in the near future. Large, pyroclastic eruptions like the climactic eruption are unlikely for thousands of years. Similarly, the release of lethal gases like carbon dioxide from Crater Lake, similar to the eruption from Lake Nyos in Cameroon in 1986, is unlikely as a result of the natural mixing of deep and surface water within the lake. There is no known mechanism by which Crater Lake's water could be catastrophically drained or by which the caldera walls would fail suddenly. Minor hydrothermal explosions could still potentially be dangerous, as the ejection of ballistic blocks or tall waves could threaten people standing near the lake, traveling at speeds from . Landslides could threaten visitors to the national park or researchers by creating tsunami-sized waves, also potentially damaging infrastructure surrounding the lake.


Recreation

Located north of the city of Klamath Falls and northeast of Medford, Crater Lake can be reached from
U.S. Route 97 U.S. Route 97 (US 97) is a major north–south route of the United States Numbered Highway System in the Pacific Northwest region. It runs for approximately through the states of California, Oregon, and Washington, primarily serving i ...
on the east, on the southwest by Highway 62, and on the northwest by Highway 138. Crater Lake and the remnants of Mount Mazama can be seen from Rim Drive, a road that surrounds the caldera, which is the only part within the Crater Lake National Park where vehicles are permitted. The Garfield Peak Trail, which runs east from the Crater Lake Lodge, offers views from above the lake's surface, with Mount Shasta visible southward. Another trail runs for from Rim Drive's eastern edge to Mount Scott, which offers views of central and southern Oregon such as the Three Sisters north of Mazama and
Mount Thielsen Mount Thielsen, or Big Cowhorn (Klamath: hisc’akwaleeʔas), is an extinct shield volcano in the Oregon High Cascades, near Mount Bailey. Because eruptive activity ceased 250,000 years ago, glaciers have heavily eroded the volcano's struc ...
, also to the north. The Cleetwood trail leads for down the northern flank of the caldera rim, eventually reaching Cleetwood Cove where boat trips run from late June or early July throughout the summer season to Wizard Island. Wizard Island can be climbed, offering views of Crater Lake. Because Mount Mazama lies within a national park area, collecting rocks within the vicinity is prohibited unless a permit is obtained. The park's facilities lie at Rim Village, at the southern edge of the caldera. Lodging and camping facilities open during the summer season between May and October. No lodges,
gas station A filling station, also known as a gas station () or petrol station (), is a facility that sells fuel and engine lubricants for motor vehicles. The most common fuels sold in the 2010s were gasoline (or petrol) and diesel fuel. Gasolin ...
s, or camping areas remain open from October through late May. Popular activities within Crater Lake National Park include
biking Cycling, also, when on a two-wheeled bicycle, called bicycling or biking, is the use of cycles for transport, recreation, exercise or sport. People engaged in cycling are referred to as "cyclists", "bicyclists", or "bikers". Apart from two ...
, fishing,
cross-country skiing Cross-country skiing is a form of skiing where skiers rely on their own locomotion to move across snow-covered terrain, rather than using ski lifts or other forms of assistance. Cross-country skiing is widely practiced as a sport and recreatio ...
, and
snowshoeing Snowshoes are specialized outdoor gear for walking over snow. Their large footprint spreads the user's weight out and allows them to travel largely on top of rather than through snow. Adjustable bindings attach them to appropriate winter footwe ...
.


See also

* Volcanic Legacy Scenic Byway


Notes


References


Citations


Sources

* * * * * * * * * * * * * * * * * * * * * * * * * {{DEFAULTSORT:Mazama, Mount Cascade Range Cascade Volcanoes Mountains of Oregon Stratovolcanoes of the United States Subduction volcanoes Calderas of Oregon Volcanoes of Oregon VEI-7 volcanoes Supervolcanoes Crater Lake National Park Mountains of Klamath County, Oregon 6th millennium BC Mountains of Douglas County, Oregon Volcanoes of Klamath County, Oregon Holocene calderas