Mount Mazama is a complex volcano in the
Oregon segment of the Cascade
Volcanic Arc and the
Cascade Range located in the United States. The
volcano's collapsed caldera holds Crater Lake, and the entire mountain
is located within
Crater Lake National Park. Its caldera was created
by an eruption 42 times greater than the 1980 eruption of Mount St.
Mazama's summit was destroyed by a volcanic eruption that occurred
around 5677 BC, ± 150 years. The eruption reduced Mazama's
approximate 12,000-foot (3,700 m) height by about 1 mile
(1,600 m). Much of the volcano fell into the volcano's partially
emptied neck and magma chamber. At 8,159 feet (2,487 m), Hillman
Peak is now the highest point on the rim.
Crater Lake National Park
1.2 Physical geography
3 Human history
5 Eruptive history
5.1 Potential hazards
6 See also
Mount Mazama lies in Klamath County, within the
U.S. state of
Oregon, 60 miles (97 km) north of the border between Oregon
California state, in the southern portion of the Cascade Range.
Inside the volcano's caldera lies Crater Lake, which has a depth of
1,943 feet (592 m) and thus represents the deepest body of
freshwater in the United States. Before its caldera-forming
eruption, Mazama stood at an elevation between 10,800 to 12,100 feet
(3,300 to 3,700 m), placing it about 1 mile (1.6 km)
above the lake and making it Oregon's highest peak. The Global
Volcanism Program currently lists its elevation at 8,159 feet
(2,487 m), while the Geographic Names Information System
provides an elevation of 6,174 feet (1,882 m).
Crater Lake National Park
Crater Lake National Park
Crater Lake National Park covers an area of 250 square miles
(650 km2), including forest areas, alpine terrain, the Crater
Lake, and the vast majority of Mount Mazama. A wilderness area, it was
dedicated in 1902 and is overseen by the National Park Service. 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.
Glaciers formed on the mountain over and over 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
observed at three large glacial canyons on its southern slopes: Kerr
Notch, Munson Balley, and Sun Notch. Whenever eruptions took place
in the presence of ice, lava was chilled by glaciers, creating glassy
talus deposits. Sometimes, the lava coursed into areas previously
carved by glaciers like at Sentinel Rock, filling canyons with
volcanic rock. Moraines occur up to 17 miles (27 km) from the rim
of Mazama's caldera and there are glacial striations visible at
several sites in the area. The most recent period of glacial
advance ceased about 27,000 years ago, so by the time Mazama collapsed
in its climactic eruption, ice was likely only present at higher
Crater Lake National Park and the area surrounding
Mount Mazama range
in elevation from 4,000 to 8,929 feet (1,219 to 2,722 m),
providing diverse habitats. The southern region of the park supports
ponderosa pine forests, and for elevations from 5,000 to 7,000 feet
(1,500 to 2,100 m), mixed coniferous, fir, and hemlock forests
are common. Subalpine zones occur above 7,000 feet (2,100 m),
often featuring whitebark pine.
The Klamath Native Americans of the area believed that the mountain
was inhabited by Llao, their god of the underworld, also known as the
"Chief of the Below World." After the mountain destroyed itself
the Klamaths recounted the events as a great battle between
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, 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
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
Klamath people believed that just looking at Mazama
would cause death; there are no tribal legends surrounding Crater
Lake, but some Native Americans still refuse to look at the water.
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 of the University of California, Berkeley, which was
published in 1942. In the paper, Williams mapped the volcano's dacite
and andesite lava flow deposits. During the 1980s, Charles Bacon
USGS geologists expanded on Williams's work, determining
more specific details about its caldera formation.
The first known European contact with Mazama occurred in the spring of
1853. Eleven miners from Yreka,
California stopped at a mercantile
store in Jacksonville,
Oregon 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 Chauncy Nye
Crater Lake area. Nye authored an article for the
Oregon Sentinel in which he wrote that he had named the
Blue Lake for its color, the first published description of
the lake. During the 1850s, Native Americans and settlers had started
to feel hostility towards each other, so
Fort Klamath was established
in 1863, 7 miles (11 km) 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
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
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 name from William G. Steel in 1896, the
founder of the climbing club The Mazamas, which formed at Mount Hood
in 1894. The word comes from an obsolete Native American word
meaning "mountain goat",[a] derived from an Aztec term to refer to
"small deer." Steel gave
United States Geological Survey 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 also holds the
Klamath name "giiwas". Steel had helped map
Crater Lake in 1886
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.
Crater Lake National Park § Geology
At the time of its collapse,
Mount Mazama encompassed an area of 150
square miles (400 km2) 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.
Mazama started to grow around 400,000 years ago in the Pleistocene,
mainly from lava flows interbedded with some pyroclastic material.
These early flows averaged 20 to 30 feet (6 to 9 m) thick and appear
to have been emplaced over a few years to a few centuries. Several
shield volcanoes were created by these flows, and numerous cinder
cones grew in the immediate area (these may or may not be parasitic
vents). More explosive eruptions started around 75,000 years ago and
built a westward-trending line of composite cones.
Cone building eruptions lasted until around 50,000 years ago when
andesite lava flowed down Mazama's north and southwest slopes.
Relatively few of the cone-building eruptions issued from the same
vent, resulting in a highly complex, approximately 11,000-foot
(3,400 m) structure made of overlapping composite cones and
shield volcanoes. Consequently, Mazama's base was broader and its
sides not as steep as today's Mount Shasta.
After its cone building phase, Mazama lavas became increasingly
silica-rich and viscous - two conditions that tend to trap explosive
gases. The first major eruption in this new cycle of Mazama's life
occurred about 10,000 years later, when dacite flows high on the
volcano's southwest face formed a series of domes. These structures
were subsequently destroyed by either collapse or steam explosions
(see phreatic eruption). Either way, their destruction created large
landslides that left deposits at the head of
Munson Valley and as far
away as Devils Backbone.
Mazama's next major eruptive period occurred between 25,000 and 30,000
years ago and extruded rhyodacite lava (which has a higher silica
content than dacite). These thick, slow-moving, pasty flows erupted
from a vent on Mazama's northeast flank and solidified to form
600-foot (180 m) high Redcloud Cliff (later cut in two by caldera
subsidence) and a dome above what today is Steel Bay.
The volcano then went dormant for roughly the next 20,000 years, while
successive ice age glaciers (probably as thick as 1,000 feet (300 m)
in troughs) cut large valleys into the mountain's sides. One of the
largest glaciers flowed down
Munson Valley near the present location
of park headquarters, down Annie Creek Valley, and perhaps as far as
Fort Klamath. When the last ice age ended 12,000 years ago, those
glaciers retreated upslope past the elevation of the current caldera's
rim. While Mazama slept, its magma chamber was going through some
differentiation, with lighter, more gas- and silica-rich rocks
collecting closer to the surface.
Around 5677 BC Mazama awoke from its slumber with explosive rhyodacite
eruptions on the northern part of the main summit where
Llao Rock now
resides. Great quantities of pumice and ash were ejected as a large
crater was excavated by the explosions. The tephra was carried by
prevailing winds to the east and southeast. Associated with this was a
pyroclastic flow that was 1.25 mi (2.0 km) wide, 1,200 feet
(370 m) thick at its deepest point, and contained
0.25 cu mi (1.0 km3) of material (later,
caldera-forming subsidence cut the partially filled crater in two,
exposing it in cross section—today this is called
One to two hundred years later (based on radiocarbon dating) the last
major eruption before the caldera was formed, the Cleetwood flow
occurred. This rhyodacite lava flow erupted from a vent near what is
now the north caldera rim. The Cleetwood flow was still fluid when the
caldera was formed, so it must have erupted just weeks to months
beforehand. When Mazama later collapsed into itself, some of the
Cleetwood lava backflowed into the caldera.
Mazama's final act started with a large eruption that sent a mile
(1.6 km) wide column of hot tephra 5 to 10 miles (8.0 to
16.1 km) into the sky at almost twice the speed of sound. The
column collapsed in a series of pyroclastic flows that covered much of
the area between and downslope of
Llao Rock and Redcloud Cliff. This
flow, the first of many, was so hot that it solidified as a welded
tuff called the Wineglass Welded Tuff. Flow after flow followed in
rapid succession, stressing the ability of Mazama's magma chamber to
recharge. The mountain started to sag under its own weight. Concentric
ring fractures formed around the volcano, creating convenient conduits
for additional volcanic vents.
The eruption entered its final and most destructive cycle with very
large and erosive pyroclastic flows erupting from ring fractures all
around the volcano. These flows moved out in all directions from
Mazama, following river valleys and in some cases not coming to rest
for 40 miles (64 km). As the eruptions were occurring, Mazama was
The collapse and the erosive ring eruptions fed each other—the
sinking volcano pushed magma upward, and the erupting material both
lubricated the downward subsidence and eroded the sides, making it
easier for much of Mazama to sink into the earth. Also, the sudden and
dramatic reduction in pressure on the remaining gas charged molten
rock in the magma chamber caused it to react by immediately exploding
into a super-heated mix of liberated gases and various grades of
pulverized and often frothy lava known as a pyroclastic flow. The
force of the explosion pulverized previously solidified rock that
happened to be nearby or that recently fell into the caldera from the
Half of 70,000-year-old Hillman Peak was blown away, exposing the cone
in cross section. Many glacier-cut canyons were beheaded and now stand
as notches in the caldera rim. Notable among these are Kerr Notch,
Munson Valley, and Sun Notch.
The last pyroclastic flow of this stage was andesitic scoria,
indicating that Mazama was drawing on material from deep within its
magma chamber. This layer of material now forms a dark band in ash
layers associated with this eruption cycle (it also created the Pumice
Desert). A last few dying gasps in the form of a series of relatively
weak explosions then deposited a well-bedded layer of pumice lapilli
and crystal-rich ash up to 50 feet (15 m) thick on the newly
formed caldera rim.
In the end, an estimated 11 to 14 cu mi (46 to 58 km3)
of magma escaped from Mazama's magma chamber during this eruptive
cycle as approximately 25 cu mi (100 km3) of tephra
(magma is compact due to high pressure surrounding it), qualifying the
eruption as a
VEI 7 event. The magma was replaced by about the same
volume of material when most of Mazama fell into its caldera. At that
time, Mazama was about 1 mile (1,600 m) shorter than its initial
height of approximately 12,000 feet (3,700 m).
Hundreds of square kilometers of the surrounding countryside were
covered by material ejected from the collapse and associated
eruptions. One pyroclastic flow traveled 40 miles (64 km) from
Rogue River Valley
Rogue River Valley while another moved north in-between
Mount Bailey and Mount Thielsen, moving over Diamond Lake (it finally
came to rest in North Umpqua
River valley). Winds carried tephra (ash
and pumice) from Mazama northeast, where it covered over
500,000 sq mi (1,300,000 km2) including nearly all of
Oregon, Washington, northern California, Idaho, western Montana, and
parts of Utah, Nevada, Wyoming, Alberta, British Columbia, and
Geologists know the exact chemical composition of this tephra (which
they call Mazama Ash) and both geologists and archeologists use the
distinctive layer it formed in a relative dating technique called
tephrochronology. As with all tephra layers, Mazama ash is thickest
near its source (20 feet (6.1 m)) and becomes thinner with
increasing distance from its source. 70 miles (110 km) northwest
it is 1 foot (30 cm) thick.
Deposits of pyroclastic flow material near Mazama remained extremely
hot for months, and, in some places, they were more than 250 feet
(76 m) deep. Hot gases escaping from the cooling deposits tended
to follow vertical channels and emerged at the surface as fumaroles.
Over time these gases cemented the channels, which are now exposed as
very tall vertical columns and spires of tuff (good examples are along
the upper walls of Sand Creek Canyon and Annie Canyon).
All volcanic activity on Mazama since its collapse has been within the
caldera. The first significant eruptive period of this phase created
an andesite lava platform (the 'central platform') that rises 1,200
feet (365 m) above the caldera floor. Later eruptions created cinder
cones such as
Wizard Island (c. 6,000 years old and 763 feet
(233 m) high) and Merriam Cone and also rhyodacite domes (most of
these features are under water).
Over time much of the approximate 4,000-foot (1,200 m) depth of
the caldera was filled with volcanic material. Part of the remainder
was filled with water from snowmelt and rain to eventually form Crater
Crater Lake reaches a maximum depth of 1,958 feet (597 m),
making it the second deepest lake in
North America (after Canada's
Great Slave Lake). The lake's great depth and purity cause it to
absorb all colors of visible light except blue, resulting in its
characteristic indigo hue.
Aerial view of Crater Lake.
Formed of a complex of stratovolcanoes and shield volcanoes, Mazama
is surrounded by monogenetic cinder cones, lava fields, and shield
volcanoes made up of calc-alkaline basalt and andesite, tholeiite, 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 lava domes
and lava flows between 700,000 and 600,000 years old, which
encompasses an area of more than 140 square miles (350 km2). 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 16-foot (5 m) thick, as well as more deposits from
more viscous andesite and dacite magma that reach thicknesses up to 98
feet (30 m). 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 in Mazama's caldera, and
lava flows cover glaciated lava deposits.
About 70,000 years ago, several silicic, 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 phyric, or chemically
evolved rhyodacite. During this period of the late
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 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 located at elevations of 7,005 feet
(2,135 m), 8,045 feet (2,452 m), and 7,949 feet
(2,423 m), 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
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
Mazama formed as a group of overlapping volcanic edifices, which
included shield volcanoes and small composite cones. Shield
volcanoes fed its 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 eruptions, 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 15 to 20 feet (4.6 to 6.1 m).
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 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.
Though the population within 6.2 miles (10 km) of
Mount Mazama is
only about 50 people, more than 270,000 live within 62 miles
(100 km) of the volcano.
United States portal
Volcanic Legacy Scenic Byway
[a] ^ The word "mazama" also means mountain goat in Spanish.
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Smithsonian Institution. Retrieved 2008-12-20.
^ a b c d "Mount Mazama". Geographic Names Information System. United
States Geological Survey. Retrieved 2006-12-20.
^ Zdanowicz, C. M.; Zielinski, G. A.; Germani, M. S. (1999). "Mount
Mazama eruption; calendrical age verified and atmospheric impact
assessed". Geology. 27 (7): 621–624. Bibcode:1999Geo....27..621Z.
^ a b c d e f g h i Mark, S. R. (September 8, 2017). "Mount Mazama".
Oregon Historical Society. Retrieved February
^ a b c d Wood & Kienle 1990, p. 193.
^ Harris 2005, p. 133.
Crater Lake National Park".
Volcano Observatory. United
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^ Harris 2005, p. 138.
^ "Crater Lake: Checklist of Birds" (PDF). National Park Service.
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^ a b c d e f g h i "Crater Lake: History" (PDF). National Park
Service. September 2001. Retrieved February 23, 2018.
^ "Volcanoes in Historical and Popular Culture: Legends and
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^ Thomas 2007, p. 49.
^ Harris 2005, p. 134.
^ Harris 2005, pp. 135–136.
^ a b c d e Harris 2005, p. 136.
^ Diller & Patton 1902, p. 1.
^ Keroher 1966, p. 2633.
^ Lewis, C. (c. 1901). "The Disappearance of Mount Mazama". Pearson's
Magazine (archived by A Place Called Oregon). Retrieved
^ Wood & Kienle 1990, pp. 193–194.
^ a b c d Wood & Kienle 1990, p. 194.
^ a b c d Harris 2005, p. 139.
^ Harris 2005, p. 140.
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Cambridge University Press. ISBN 0-521-43811-X.
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