110-602: The Three Sisters are closely spaced volcanic peaks in the U.S. state of Oregon . They are part of the Cascade Volcanic Arc , a segment of the Cascade Range in western North America extending from southern British Columbia through Washington and Oregon to Northern California . Each over 10,000 feet (3,000 meters) in elevation, they are the third-, fourth- and fifth-highest peaks in Oregon. Located in
220-452: A false peak , formed between 28,000 and 24,000 years ago, roughly around the same time as the main cone. Despite its relatively young age, every part of South Sister other than its peak has undergone significant erosion due to Pleistocene and Holocene glaciation. Between 30,000 and 15,000 years ago, South Sister's southern flanks were covered with ice streams , and a small amount of ice extended below 3,600 ft (1,100 m). On
330-486: A tectonic plate that poses a continued threat of volcanic activity and earthquakes in the region. The most recent major activity was the 1700 Cascadia earthquake . Washington 's Mount St. Helens erupted in 1980 , an event visible from northern Oregon and affecting some areas there. The Columbia River, which forms much of Oregon's northern border, also played a major role in the region's geological evolution, as well as its economic and cultural development. The Columbia
440-581: A "g". Another possible source is the Spanish word oregano , which refers to a plant that grows in the southern part of the region. It is also possible that the area around the Columbia River was named after a stream in Spain called "Arroyo del Oregón", located in the province of Ciudad Real . Another early use of the name, spelled Ouragon , was by Major Robert Rogers in a 1765 petition to
550-473: A broad andesitic cone, forming a steep summit cone of andesite about 27,000 years ago. South Sister remained dormant for 15,000 years, after which its composition shifted from dacitic to more rhyolitic lava. An eruptive episode about 2,200 years ago, termed the Rock Mesa eruptive cycle, first spread volcanic ash from flank vents from the south and southwest flanks, followed by a thick rhyolite lava flow. Next,
660-520: A large winter snowpack, with low temperatures for much of the year. There are patches of mountain hemlock, subalpine fir, and whitebark pine near the treeline, as well as wet meadows supporting Brewer's sedge , Holm's sedge , black alpine sedge , tufted hairgrass, and alpine aster . Near the peaks of the Three Sisters, there are extensive areas of bare rock. The lower eastern slopes of the Three Sisters below 5,200 ft (1,600 m) lie in
770-510: A probate government was proposed. Doctor Ira Babcock of Jason Lee 's Methodist Mission was elected supreme judge. Babcock chaired two meetings in 1842 at Champoeg , (halfway between Lee's mission and Oregon City ), to discuss wolves and other animals of contemporary concern. These meetings were precursors to an all-citizen meeting in 1843, which instituted a provisional government headed by an executive committee made up of David Hill , Alanson Beers , and Joseph Gale . This government
880-622: A railroad in 1851 from St. Helens, through the Cornelius pass and across Washington County to the city of Lafayette, which was at the time the big town of the Willamette Valley. In December 1844, Oregon passed its first black exclusion law , which prohibited African Americans from entering the territory while simultaneously prohibiting slavery . Slave owners who brought their slaves with them were given three years before they were forced to free them. Any African Americans in
990-586: A refuge from disputes over slavery, Oregon had a "whites only" clause in its original state Constitution. At the outbreak of the American Civil War , regular U.S. troops were withdrawn and sent east to aid the Union . Volunteer cavalry recruited in California were sent north to Oregon to keep peace and protect the populace. The First Oregon Cavalry served until June 1865. Beginning in the 1880s,
1100-590: A round trip of 16.4 mi (26.4 km) and an elevation gain of 4,757 ft (1,450 m). South Sister is the easiest of the three to climb, and has a trail all the way to the summit. The standard route up the south ridge runs for 12.6 mi (20.3 km) round trip, rising from 5,446 ft (1,660 m) at the trailhead to 10,363 ft (3,159 m) at its summit. It is a popular climb during August and September, with up to 400 people each day. Oregon Oregon ( / ˈ ɒr ɪ ɡ ən , - ɡ ɒ n / ORR -ih-ghən , -gon )
1210-541: A sudden avalanche; this flash flood reached the Cascade Lakes Scenic Byway . Concerned about the hazard of similar flooding events, scientists in the 1980s from the U.S. Geological Survey (USGS) identified that Carver Lake on South Sister could flood and breach its natural dam , producing a large mudflow that could endanger wilderness visitors and the town of Sisters. Studies at Collier Lake and Diller Lake suggested that both had breached their dams in
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#17328010769691320-689: A third of the Three Sisters Wilderness, and this area is known as the Alpine Crest Region. Rising from about 5,200 ft (1,600 m) to 10,358 ft (3,157 m) in elevation, the Alpine Crest Region features the wilderness area's most-frequented glaciers, lakes, and meadows. Weather varies greatly in the area due to the rain shadow caused by the Cascade Range. Air from the Pacific Ocean rises over
1430-504: A threat to nearby life, as the proximal danger zone extends 1.2 to 6.2 mi (2 to 10 km) from the volcano's summits. During an eruption, tephra could accumulate to 1 to 2 in (25 to 51 millimetres) in the city of Bend, and mudflows and pyroclastic flows could run down the sides of the mountain, threatening any life in their paths. Eruptions from South Sister could be either explosive or effusive , though an eruption of ash with local volcanic rock accumulation and slow lava flows
1540-550: A água , Oregon. Yet another account, endorsed as the "most plausible explanation" in the book Oregon Geographic Names , was advanced by George R. Stewart in a 1944 article in American Speech . According to Stewart, the name came from an engraver's error in a French map published in the early 18th century, on which the Ouisiconsink (Wisconsin) River was spelled " Ouaricon-sint ", broken on two lines with
1650-474: Is 10,090 ft (3,075 m). Consisting primarily of basaltic andesite , it has a more mafic composition than the other two volcanoes. Its deposits are rich in palagonite and red and black cinders , and they are progressively more iron-rich the younger they are. North Sister's lava flows demonstrate similar compositions throughout the mountain's long eruptive history. The oldest lava flows on North Sister have been dated to roughly 311,000 years ago, though
1760-936: Is a state in the Pacific Northwest region of the United States. It is a part of the Western U.S. , with the Columbia River delineating much of Oregon's northern boundary with Washington , while the Snake River delineates much of its eastern boundary with Idaho . The 42° north parallel delineates the southern boundary with California and Nevada . The western boundary is formed by the Pacific Ocean . Oregon has been home to many indigenous nations for thousands of years. The first European traders, explorers, and settlers began exploring what
1870-431: Is a predominantly rhyolitic stratovolcano overlying an older shield structure. Its modern structure is no more than 50,000 years old, and it last erupted about 2,000 years ago. Although its first eruptive events from 50,000 to 30,000 years ago were predominantly rhyolitic, between 38,000 and 32,000 years ago the volcano began to alternate between dacitic /rhyodacitic and rhyolitic eruptions. The volcano built
1980-525: Is considered most likely. The Three Sisters area does not have fumarole activity, although there are hot springs west of South Sister. From 1986 to 1987, the USGS surveyed the Three Sisters vicinity with tilt-leveling networks and electro-optical distance meters, but South Sister was not the subject of close geodetic analysis until the early 2000s. In 2001, scientists inferred magmatic activity near South Sister from InSAR satellite data that showed uplift of
2090-539: Is evidence supporting inhabitants in the region at least 15,000 years ago. By 8000 BC, there were settlements throughout the state, with populations concentrated along the lower Columbia River, in the western valleys, and around coastal estuaries. During the prehistoric period , the Willamette Valley region was flooded after the collapse of glacial dams from then Lake Missoula , located in what would later become Montana . These massive floods occurred during
2200-461: Is in this region of the state. Typical of a western state, Oregon is home to a unique and diverse array of wildlife. Roughly 60 percent of the state is covered in forest, while the areas west of the Cascades are more densely populated by forest, making up around 80 percent of the landscape. Some 60 percent of Oregon's forests are within federal land. Oregon is the top timber producer of
2310-536: Is less viscous ; it produces lava flows and is less prone to explosive eruptions than silicic magma. The region was active in the Pleistocene, with eruptions between about 650,000 and about 250,000 years ago from an explosively active complex known as the Tumalo volcanic center . This area features andesitic and mafic cinder cones such as Lava Butte , as well as rhyolite domes . Cinder cones accumulate from
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#17328010769692420-786: Is now Oregon's Pacific coast in the early to mid-16th century. As early as 1564, the Spanish began sending vessels northeast from the Philippines , riding the Kuroshio Current in a sweeping circular route across the northern part of the Pacific. In 1592, Juan de Fuca undertook detailed mapping and studies of ocean currents in the Pacific Northwest, including the Oregon coast as well as the strait now bearing his name. The Lewis and Clark Expedition traversed Oregon in
2530-473: Is now allowed in Oregon, gas stations are not required to offer it and many currently do not. New Jersey is the only state remaining where self serve gas stations are not allowed. Oregon is 295 miles (475 km) north to south at longest distance, and 395 miles (636 km) east to west. With an area of 98,381 square miles (254,810 km ), Oregon is slightly larger than the United Kingdom . It
2640-730: Is one of North America's largest rivers, and one of two rivers to cut through the Cascades (the Klamath River in southern Oregon is the other). About 15,000 years ago, the Columbia repeatedly flooded much of Oregon during the Missoula Floods ; the modern fertility of the Willamette Valley is largely the result. Plentiful salmon made parts of the river, such as Celilo Falls , hubs of economic activity for thousands of years. Today, Oregon's landscape varies from rain forest in
2750-487: Is probable some still move into eastern Oregon from Idaho. Oregon is home to what is considered the largest single organism in the world, an Armillaria solidipes fungus beneath the Malheur National Forest of eastern Oregon. Oregon has several National Park System sites , including Crater Lake National Park in the southern part of the Cascades, John Day Fossil Beds National Monument east of
2860-460: Is rounded down phonetically, from Ouve água —Oragua, Or-a-gon, Oregon—given probably by the same Portuguese navigator that named the Farallones after his first officer, and it literally, in a large way, means cascades: "Hear the waters." You should steam up the Columbia and hear and feel the waters falling out of the clouds of Mount Hood to understand entirely the full meaning of the name Ouve
2970-602: Is the most dangerous climb of the three peaks, and is often informally called the "Beast of the Cascades". One of its peaks, Little Brother, can be safely scrambled . The first recorded ascent of North Sister was made in 1857 by six people, including Oregon politicians George Lemuel Woods and James McBride , according to a story published in Overland Monthly in 1870. Today, the common trail covers 11 mi (18 km) round-trip, gaining 3,165 ft (965 m) in elevation. Middle Sister can also be scrambled, for
3080-469: Is the ninth largest state in the U.S. Oregon's highest point is the summit of Mount Hood, at 11,249 feet (3,429 m), and its lowest point is the sea level of the Pacific Ocean along the Oregon Coast. Oregon's mean elevation is 3,300 feet (1,006 m). Crater Lake National Park , the state's only national park, is the site of the deepest lake in the U.S. at 1,943 feet (592 m). Oregon claims
3190-484: Is the state's highest point. Oregon's only national park, Crater Lake National Park , comprises the caldera surrounding Crater Lake , the deepest lake in the U.S. The state is also home to the single largest organism in the world, Armillaria ostoyae , a fungus that runs beneath 2,200 acres (8.9 km ) of the Malheur National Forest . Oregon's economy has historically been powered by various forms of agriculture, fishing, logging, and hydroelectric power. Oregon
3300-450: Is the thickest and largest glacier in the region, descends along the north side of Middle Sister, cutting into the west side of North Sister. Erosion from Pleistocene and Holocene glaciation exposed a plug near the center of Middle Sister. South Sister, also known as "Charity", is the tallest volcano of the trio, standing at 10,363 ft (3,159 m). The eruptive products range from basaltic andesite to rhyolite and rhyodacite . It
3410-606: Is the third-most populous city in Oregon, with 175,535 residents. Portland , with 652,503, ranks as the 26th among U.S. cities. The Portland metropolitan area , which includes neighboring counties in Washington, is the 25th largest metro area in the nation, with a population of 2,512,859. Oregon is also one of the most geographically diverse states in the U.S., marked by volcanoes, abundant bodies of water, dense evergreen and mixed forests, as well as high deserts and semi-arid shrublands . At 11,249 feet (3,429 m), Mount Hood
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3520-605: Is the top lumber producer of the contiguous U.S. , with the lumber industry dominating the state's economy during the 20th century. Technology is another one of Oregon's major economic forces, beginning in the 1970s with the establishment of the Silicon Forest and the expansion of Tektronix and Intel . Sportswear company Nike, Inc. , headquartered in Beaverton , is the state's largest public corporation with an annual revenue of $ 46.7 billion. The origin of
3630-420: Is unusual relative to nearby peaks. The Three Sisters form the leading edge of a rhyolitic crustal-melting anomaly, which might be explained by a combination of mantle flow (movement of Earth's solid silicate mantle layer caused by convection currents) and decompression that has generated similar melting and rhyolitic volcanism nearby for the past 16 million years. The three mountains were also shaped by
3740-562: The -sint below, so there appeared to be a river flowing to the west named " Ouaricon ". According to the Oregon Tourism Commission , present-day Oregonians / ˌ ɒr ɪ ˈ ɡ oʊ n i ə n z / pronounce the state's name as "or-uh-gun, never or-ee-gone". After being drafted by the Detroit Lions in 2002, former Oregon Ducks quarterback Joey Harrington distributed "Orygun" stickers to members of
3850-532: The Seattle Weekly Gazette reported that one of the Three Sisters emitted some fire and smoke. In the late 19th century, there was extensive wool production in eastern Oregon. Shepherds led their herds of 1,500 to 2,500 sheep to the Three Sisters. They arrived in eastern foothills near Whychus Creek by May or June, and then climbed to higher pastures in August and September. By the 1890s, the area
3960-574: The Cascade Range at an elevation of over 8,000 feet (2,400 m). It is on the east slopes of North Sister , an extinct shield volcano . In August 2020 the Oregon Glaciers Institute reported that Thayer Glacier no longer has active, moving ice. This article about a glacier in the United States is a stub . You can help Misplaced Pages by expanding it . This Deschutes County , Oregon state location article
4070-580: The Cascade Volcanoes . These volcanoes, including the Three Sisters, were fed by magma chambers resulting from the subduction of the Juan de Fuca tectonic plate under the western edge of the North American tectonic plate . Each of the three volcanoes formed at different times from several variable magmatic sources. The amount of rhyolite present in the lavas of the younger two mountains
4180-739: The Columbia Plateau , the High Desert , and the Blue Mountains . Oregon lies in two time zones . Most of Malheur County is in the Mountain Time Zone , while the rest of the state lies in the Pacific Time Zone . Western Oregon's mountainous regions, home to three of the most prominent mountain peaks of the U.S. including Mount Hood, were formed by the volcanic activity of the Juan de Fuca Plate ,
4290-519: The Columbian black-tailed deer , mule deer , Roosevelt elk , and American black bear . Bobcats , cougars , coyotes , wolverines , martens , badgers , weasels , bald eagles , and several hawk species are many of the predators throughout the Three Sisters area. The Three Sisters area was occupied by Amerindians since the end of the last glaciation, mainly the Northern Paiute to
4400-648: The D River as the shortest river in the world, though the state of Montana makes the same claim of its Roe River . Oregon is also home to Mill Ends Park (in Portland), the smallest park in the world at 452 square inches (0.29 m ). Oregon is split into eight geographical regions. In Western Oregon : Oregon Coast (west of the Coast Range ), the Willamette Valley, Rogue Valley , Cascade Range and Klamath Mountains ; and in Central and Eastern Oregon :
4510-934: The Kingdom of Great Britain . The term referred to the then-mythical River of the West (the Columbia River). By 1778, the spelling had shifted to Oregon . Rogers wrote: ... from the Great Lakes towards the Head of the Mississippi, and from thence to the River called by the Indians Ouragon ... One suggestion is that this name comes from the French word ouragan ("windstorm" or "hurricane"), which
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4620-597: The Lewis and Clark and Astor Expeditions. Few stayed permanently such as Étienne Lussier, often referred to as the first "European" farmer in the state of Oregon. Evidence of the French Canadian presence can be found in numerous names of French origin such as Malheur Lake , the Malheur , Grande Ronde , and Deschutes Rivers , and the city of La Grande . Furthermore, many of the early pioneers first came out West with
4730-515: The Miocene or early Pliocene epochs. Naming this ancient volcano Mount Multnomah , Hodge theorized that it had collapsed to form a caldera just as Mount Mazama collapsed to form Crater Lake . In the 1940s, Howel Williams completed an analysis of the Three Sisters vicinity and concluded that Multnomah had never existed, instead demonstrating that each volcano in the area possessed its own individual eruptive history. Williams' 1944 paper defined
4840-763: The North West Company and the Hudson's Bay Company before heading South of the Columbia for better farmland as the fur trade declined. French Prairie by the Willamette River and French Settlement by the Umpqua River are known as early mixed ancestry settlements. The Lewis and Clark Expedition traveled through northern Oregon also in search of the Northwest Passage . They built their winter fort in 1805–1806 at Fort Clatsop , near
4950-815: The Ponderosa Pine/Bitterbrush Woodland ecoregion . This ecoregion has less precipitation than the western slopes and has soil derived from Mazama Ash (ash erupted from Mount Mazama). Stream flow changes little throughout the year due to the region's volcanic hydrogeology . These slopes support nearly pure stands of ponderosa pine. Understory vegetation includes greenleaf manzanita and snowberry at higher elevations and antelope bitterbrush at lower elevations. Mountain alder , stream dogwood , willows , and sedges grow along streams . Local fauna includes birds such as blue and ruffed grouse , small mammals like pikas , chipmunks , and golden-mantled ground squirrels , and larger species like
5060-662: The Three Sisters Wilderness at the boundary of Lane and Deschutes counties and the Willamette and Deschutes national forests, they are about 10 miles (16 kilometers) south of the nearest town, Sisters . Diverse species of flora and fauna inhabit the area, which is subject to frequent snowfall, occasional rain, and extreme temperature variation between seasons. The mountains, particularly South Sister, are popular destinations for climbing and scrambling . Although they are often grouped together as one unit,
5170-820: The United States Geological Survey improved monitoring in the immediate area. The Three Sisters are at the boundary of Lane and Deschutes counties and the Willamette and Deschutes national forests in the U.S. state of Oregon, about 10 miles (16 kilometers) south of the nearest town of Sisters . The three peaks are the third-, fourth-, and fifth-highest in Oregon, and contain 16 named glaciers. Their ice volume totals 5.6 billion cubic feet (160 million cubic metres). The Sisters were named Faith, Hope and Charity by early settlers, but are now known as North Sister, Middle Sister and South Sister, respectively. The Three Sisters Wilderness covers an area of 281,190 acres (1,137.9 km), making it
5280-432: The forced relocation of the native population to Indian reservations in Oregon . The first Oregon proposition for a railroad in Oregon was made in 1850 by H. M. Knighton, the original owner of the townsite of St. Helens . Knighton asserted that this would fulfill his township's belief that it should be the supreme metropolitan seaport in that area upon the Columbia River, as opposed to Portland. He suggested building
5390-519: The last glacial period and filled the valley with 300 to 400 feet (91 to 122 m) of water. By the 16th century, Oregon was home to many Native American groups, including the Chinook , Coquille (Ko-Kwell), Bannock , Kalapuya , Klamath , Klickitat , Molala , Nez Perce , Shasta , Takelma , Umatilla , and Umpqua . The first Europeans to visit Oregon were Spanish explorers led by Juan Rodríguez Cabrillo , who sighted southern Oregon off
5500-406: The Cascades, Lewis and Clark National Historical Park on the north coast, and Oregon Caves National Monument near the south coast. Other areas that were considered for potential national park status in the 20th century include the southern Oregon Coast, Mount Hood, and Hells Canyon to the east. Thayer Glacier Thayer Glacier is in the U.S. state of Oregon . The glacier is situated in
5610-548: The Coast Range to barren desert in the southeast, which still meets the technical definition of a frontier . Oregon's geographical center is further west than any of the other 48 contiguous states (although the westernmost point of the lower 48 states is in Washington). Central Oregon 's geographical features range from high desert and volcanic rock formations resulting from lava beds . The Oregon Badlands Wilderness
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#17328010769695720-648: The Collier Glacier. According to sources, the Prouty Glacier is sometimes considered to be larger than the Collier glacier. When Little Ice Age glaciers retreated during the 20th century, water filled in the spaces left behind, forming moraine-dammed lakes , which are more common in the Three Sisters Wilderness than anywhere else in the contiguous U.S. The local area has a history of flash floods , including an event on October 7, 1966, caused by
5830-492: The Devils Hill eruptive cycle consisted of explosive ash eruptions followed by viscous rhyolitic lava flows. Unlike the previous eruptive period, it was caused by the intrusion of a dike of new silicic magma that erupted from 20 vents on the southeast side and from a smaller line on the north side. These eruptions generated pyroclastic flows and lava domes from vents on the northern, southern, eastern, and southeastern sides of
5940-705: The Forest Service decided to reclassify the area as a wilderness area and removed the old-growth forest of the French Pete Creek basin, despite protests of local environmental activists. The area became part of the National Wilderness Preservation System when the Wilderness Act of 1964 was passed, but the area still excluded the French Pete Creek basin. Responding to environmental mobilization throughout
6050-421: The Hudson's Bay Company, reversed the Hudson's Bay Company's long-standing policy of discouraging settlement because it interfered with the lucrative fur trade. He directed that some 200 Red River Colony settlers be relocated to HBC farms near Fort Vancouver, (the James Sinclair expedition), in an attempt to hold Columbia District. Starting in 1842–1843, the Oregon Trail brought many new American settlers to
6160-455: The North Sister summit, while the Thayer Glacier is on its eastern slope. The Collier Glacier is nestled between North Sister and Middle Sister and flows to the northwest. The Renfrew and Hayden Glaciers are on the northwestern and northeastern slopes of Middle Sister, respectively, while the Diller Glacier is on its southeastern slope. The Irving , Carver and Skinner Glaciers lie between Middle Sister and South Sister. Finally, around
6270-418: The Oregon Country. Oregon's boundaries were disputed for a time, contributing to tensions between the U.K. and the U.S., but the border was defined peacefully in the 1846 Oregon Treaty . The border between the U.S. and British North America was set at the 49th parallel . The Oregon Territory was officially organized on August 13, 1848. Settlement increased with the Donation Land Claim Act of 1850 and
6380-534: The Pacific Northwest was particularly affected by the 1973 oil crisis , with Oregon suffering a substantial shortage. In 1972, the Oregon Beverage Container Act of 1971, popularly called the Bottle Bill, became the first law of its kind in the United States. The Bottle Bill system in Oregon was created to control litter. In practice, the system promotes recycling, not reusing, and the collected containers are generally destroyed and made into new containers. Ten states currently have similar laws. In 1994, Oregon became
6490-562: The Pacific coast in 1543. Sailing from Central America on the Golden Hind in 1579 in search of the Strait of Anian during his circumnavigation of the Earth , the English explorer and privateer Sir Francis Drake briefly anchored at South Cove, Cape Arago , just south of Coos Bay , before sailing for what is now California. Martín de Aguilar , continuing separately from Sebastián Vizcaíno 's scouting of California, reached as far north as Cape Blanco and possibly to Coos Bay in 1603. Exploration continued routinely in 1774, starting with
6600-416: The Three Sisters Wilderness, leaving the area closed until May 2013. In August 2017, officials closed 417 sq mi (1,080 km) in the western half of the Three Sisters Wilderness, including 24 mi (39 km) of the Pacific Crest Trail , to the public because of 11 lightning-caused fires, including the Milli Fire . As a result of the increasing incidence of fires, public officials have factored
6710-547: The Three Sisters reflect their location in central Oregon's Cascade Range. The westside slopes from 3,000 to 6,500 ft (910 to 2,000 m) lie in the Western Cascade Montane Highlands ecoregion , where precipitation is abundant. Forests here consist predominantly of Douglas-fir and western hemlock , with minor components of mountain hemlock , noble fir , subalpine fir , grand fir , Pacific silver fir , red alder , and Pacific yew . Vine maples , rhododendron , Oregon grape , huckleberry , and thimbleberry grow beneath
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#17328010769696820-407: The West, although the periodic fluctuations in the U.S. building industry have hurt the state's economy on multiple occasions. Portland, in particular, experienced a population boom between 1900 and 1930, tripling in size; the arrival of World War II also provided the northwest region of the state with an industrial boom, where Liberty ships and aircraft carriers were constructed. During the 1970s,
6930-448: The abundance of fur-bearing animals in the area. Also in 1811, New Yorker John Jacob Astor financed the establishment of Fort Astoria at the mouth of the Columbia River as a western outpost to his Pacific Fur Company ; this was the first permanent European settlement in Oregon. In the War of 1812 , the British gained control of all Pacific Fur Company posts. The Treaty of 1818 established joint British and American occupancy of
7040-412: The airfall of many pyroclastic rock fragments of various sizes, while the viscous rhyolite domes extrude onto the surface like toothpaste. The Tumalo volcano spread ignimbrites and plinian deposits in ground eruptions across the area, similar to the eruption of Vesuvius that destroyed Pompeii . These deposits spread from Tumalo to the town of Bend . Basaltic lava flows from North Sister overlay
7150-468: The area of uplift. The hundreds of small earthquakes subsided after several days. According to a 2011 study, this swarm may have initiated a significant decrease in the peak uplift rate. GPS and satellite observations showed that the rate of uplift west of South Sister gradually decreased from 2001 to 2020. A small increase in the uplift rate began in the same area between 2020 and 2021, and small earthquake swarms were recorded in 2021 and 2022. The ecology of
7260-419: The basic outline of the Three Sisters vicinity, though he lacked access to chemical techniques and radiometric dating . Over the past 70 years, scientists have published several reconnaissance maps and petrographic studies of the Three Sisters, including a detailed geological map published in 2012. Neither North nor Middle Sister is likely to resume volcanic activity. An eruption from South Sister would pose
7370-403: The botanist David Douglas reported snow-covered peaks visible from the Willamette Valley . As the Willamette Valley was gradually colonized in the 1840s, Euro-Americans approached the summits from the west and probably named them individually at that time. Explorers, such as Nathaniel Jarvis Wyeth in 1839 and John Frémont in 1843, used the Three Sisters as a landmark from the east. The area
7480-403: The changing climate of the Pleistocene epoch, during which multiple glacial periods occurred and glaciers eroded the mountains. The Three Sisters form the center of a region of closely grouped volcanic peaks. This is in contrast to the typical 40-to-60 mi (64-to-97 km) spacing between volcanoes elsewhere in the Cascades. Among the most active volcanic areas in the Cascades and one of
7590-429: The crater rim significantly steeper. The slopes of South Sister contain small glaciers, including the Lost Creek and Prouty glaciers. When the first geological reconnaissance of the Three Sisters region was published in 1925, its author, Edwin T. Hodge, suggested that the Three Sisters and five smaller mountains in the present-day wilderness area were the remains of an enormous collapsed volcano that had been active during
7700-426: The cumulative magma intrusion as 50 to 70 million cubic metres (1.8 × 10 ^ to 2.5 × 10 ^ cu ft) in volume. Beginning in 2001, the Cascades Volcano Observatory conducted field surveys and installed two new monitoring stations near the Three Sisters, including a GPS station and seismometer at The Husband, a peak west of the Three Sisters. In 2004, this seismometer detected an earthquake swarm in
7810-465: The early 1800s, and the first permanent European settlements in Oregon were established by fur trappers and traders. In 1843, an autonomous government was formed in the Oregon Country , and the Oregon Territory was created in 1848. Oregon became the 33rd state of the U.S. on February 14, 1859. Today, with 4.2 million people over 98,000 square miles (250,000 km ), Oregon is the ninth largest and 27th most populous U.S. state. The capital, Salem ,
7920-500: The early 1940s and in 1970, respectively. Other moraine-dammed lakes within the wilderness area include Thayer Lake on North Sister's east flank and four members of the Chambers Lakes group between Middle and South Sister. Before settlement of the area at the end of the 19th century, wildfires frequently burned through the local forests, especially the ponderosa pine forests on the eastern slopes. Due to fire suppression over
8030-408: The east and Molala to the west. They harvested berries, made baskets, hunted, and made obsidian arrowheads and spears. Traces of rock art can be seen at Devils Hill, south of South Sister. The first Westerner to discover the Three Sisters was the explorer Peter Skene Ogden of the Hudson's Bay Company in 1825. He describes "a number of high mountains" south of Mount Hood. Ten months later in 1826,
8140-483: The eastern slopes varies from 40 to 80 in (100 to 200 cm) in the east. Temperature extremes reach 80 to 90 degrees Fahrenheit (27 to 32 degrees Celsius) in summers and −20 to −30 °F (−29 to −34 °C) during the winters. The Three Sisters have about 130 snowfields and glaciers ranging in altitude from 6,742 to 10,308 ft (2,055 to 3,142 m) with a cumulative surface area of about 2,500 acres (10 km). The Linn and Villard Glaciers are north of
8250-473: The expedition of the frigate Santiago by Juan José Pérez Hernández , and the coast of Oregon became a valuable trade route to Asia. In 1778, British captain James Cook also explored the coast. French Canadians , Scots , Métis , and other continental natives (e.g. Iroquois ) trappers arrived in the late 18th and early 19th centuries, soon to be followed by Catholic clergy. Some traveled as members of
8360-499: The first U.S. state to legalize physician-assisted suicide through the Oregon Death with Dignity Act . A measure to legalize recreational use of marijuana in Oregon was approved on November 4, 2014, making Oregon only the second state at the time to have legalized gay marriage , physician-assisted suicide, and recreational marijuana. Self service gasoline was banned in Oregon from 1951 until August 2023. Although self-serve
8470-480: The glacier from 1910 to 1994. In the 1930s, the Three Sisters were part of a proposed National Monument . To maintain its authority over the region, the Forest Service decided to create a 191,108-acre (773 km) primitive area in 1937. The following year, at the instigation of Forest Service employee Bob Marshall , it was expanded by 55,620 acres (225 km) in the French Pete Creek basin. In 1957,
8580-516: The ground surface in an area centered approximately 3 mi (4.8 km) west of the mountain. The data showed a maximum of approximately 130 mm (5.1 in) of uplift from 1995 to 2001. The inflation episode was probably caused by the accumulation of magma or hot water and gases about 6 to 7 km (3.7 to 4.3 mi) underground. A 2002 study inferred that the inflation was due to intruding magma, likely of basaltic to rhyolitic composition, into an existing magma reservoir. A 2011 study described
8690-487: The growth of railroads expanded the state's lumber , wheat , and other agricultural markets, and the rapid growth of its cities. Due to the abundance of timber and waterway access via the Willamette River, Portland became a major force in the lumber industry of the Pacific Northwest , and quickly became the state's largest city. It would earn the nickname "Stumptown", and would later become recognized as one of
8800-496: The lower 48 states. Moose have not always inhabited the state but came to Oregon in the 1960s; the Wallowa Valley herd numbered about 60 as of 2013 . Gray wolves were extirpated from Oregon around 1930 but have since found their way back; most reside in northeast Oregon, with two packs living in the south-central part. Although their existence in Oregon is unconfirmed, reports of grizzly bears still turn up, and it
8910-780: The main crest of the Cascade Range, stretching from the Columbia River almost to the border with California . In 1905, administration of the Reserve was moved from the United States General Land Office to the United States Forest Service . The Reserve was renamed the Cascade National Forest in 1907. In 1908, the forest was split: the eastern half became the Deschutes National Forest, while
9020-608: The media as a reminder of how to pronounce the name of his home state. The stickers are sold by the University of Oregon Bookstore . While there is considerable evidence that Paleo-Indians inhabited the region, the oldest evidence of habitation in Oregon was found at Fort Rock Cave and the Paisley Caves in Lake County . Archaeologist Luther Cressman dated material from Fort Rock to 13,200 years ago, and there
9130-477: The most dangerous port cities in the United States due to racketeering and illegal activities at the turn of the 20th century. In 1902, Oregon introduced direct legislation by the state's citizens through initiatives and referendums , known as the Oregon System . On May 5, 1945, six civilians were killed by a Japanese balloon bomb that exploded on Gearhart Mountain near Bly . They remained
9240-452: The most densely populated volcanic centers in the world, the Three Sisters region includes nearby peaks such as Belknap Crater , Mount Washington , Black Butte , and Three Fingered Jack to the north, and Broken Top and Mount Bachelor to the south. Most of the surrounding volcanoes consist of mafic (basaltic) lavas; only South and Middle Sister have an abundance of silicic rocks such as andesite , dacite , and rhyodacite . Mafic magma
9350-500: The mountain is cone-shaped. The eastern side has been heavily eroded by glaciation, while the western face is mostly intact. Of the Three Sisters, Middle Sister has the largest ice cover. The Hayden and Diller glaciers continue to cut into the east face, while the Renfrew Glacier sits on the northwestern slope. The large but retreating Collier Glacier , which contains 700 million cubic feet (20 × 10 ^ m) of ice and
9460-595: The mouth of the Columbia River, staying at the encampment from December until March. British explorer David Thompson also conducted overland exploration. In 1811, while working for the North West Company, Thompson became the first European to navigate the entire Columbia River. Stopping on the way, at the junction of the Snake River, he posted a claim to the region for Great Britain and the North West Company. Upon returning to Montreal , he publicized
9570-526: The oldest reliably dated deposits are approximately 119,000 years old. Estimates place the volcano's last eruption at 46,000 years ago, in the Late Pleistocene . North Sister possesses more dikes than any similar Cascade peak, caused by lava intruding into pre-existing rocks. Many of these dikes were pushed aside by the intrusion of a 980 ft (300 m)-wide volcanic plug . The dikes and plug were exposed by centuries of erosion. At one point,
9680-539: The only people on American soil whose deaths were attributed to an enemy balloon bomb explosion during World War II . The bombing site is now located in the Mitchell Recreation Area . Industrial expansion began in earnest following the 1933–1937 construction of the Bonneville Dam on the Columbia River. Hydroelectric power , food, and lumber provided by Oregon helped fuel the development of
9790-460: The past century, the forests have become overgrown, and at higher elevations, they are further susceptible to summertime fires, which threaten surrounding life and property. In the 21st century, wildfires have been larger and more common in the Deschutes National Forest. In September 2012, a lightning strike caused a fire that burned 41 square miles (110 km) in the Pole Creek area within
9900-410: The region after the law was passed were forced to leave, and those who did not comply were arrested and beaten. They received no less than twenty and no more than thirty-nine stripes across the back if they still did not leave. This process could be repeated every six months. Slavery played a major part in Oregon's history and even influenced its path to statehood. The territory's request for statehood
10010-637: The region west of the Rocky Mountains to the Pacific Ocean. By the 1820s and 1830s, the Hudson's Bay Company dominated the Pacific Northwest from its Columbia District headquarters at Fort Vancouver (built in 1825 by the district's chief factor, John McLoughlin , across the Columbia from present-day Portland ). In 1841, the expert trapper and entrepreneur Ewing Young died leaving considerable wealth and no apparent heir, and no system to probate his estate. A meeting followed Young's funeral, at which
10120-492: The role of wildfire into planning, including organizing prescribed fires with scientists to protect habitats at risk while minimizing adverse effects on air quality and environmental health. The Three Sisters join several other volcanoes in the eastern segment of the Cascade Range known as the High Cascades, which trends north–south. The High Cascades are the most recent volcanic arc in the Pacific Northwest, which forms
10230-653: The second-largest wilderness area in Oregon. Designated by the United States Congress in 1964, it borders the Mount Washington Wilderness to the north and shares its southern edge with the Waldo Lake Wilderness . The area includes 260 mi (420 km) of trails and many forests, lakes, waterfalls, and streams, including the source of Whychus Creek . The Three Sisters and nearby Broken Top account for about
10340-647: The state of Oregon, Congress passed the Endangered American Wilderness Act of 1978 , which led to the reinstatement of French Pete Creek and its surroundings in the Three Sisters Wilderness Area. The Oregon Wilderness Act of 1984 further expanded the wilderness with the addition of 38,100 acres (154 km) around Erma Bell Lakes. The Three Sisters are a popular climbing destination for hikers and mountaineers . Due to extensive erosion and rockfall, North Sister
10450-421: The state's name is uncertain. The earliest geographical designation "orejón" (meaning "big ear") comes from the Spanish historical chronicle Relación de la Alta y Baja California (1598), written by Rodrigo Montezuma of New Spain ; here it refers to the region of the Columbia River as it was encountered by the first Spanish scouts. The " j " in the Spanish phrase " El Orejón " was eventually corrupted into
10560-476: The summit of South Sister, in a clockwise direction, are the Prouty , Lewis , Clark , Lost Creek , and Eugene Glaciers . The Collier Glacier, despite a 4,900 ft (1,500 m) retreat and a 64% loss of its surface area between 1910 and 1994, is generally considered to be the largest glacier of the Three Sisters at 160 acres (0.65 km). Eliot Glacier on Mount Hood is now two-and-a-half times larger than
10670-417: The three mountains have their own individual geology and eruptive history. Neither North Sister nor Middle Sister has erupted in the last 14,000 years, and it is considered unlikely that either will ever erupt again. South Sister last erupted about 2,000 years ago and could erupt in the future, threatening life within the region. After satellite imagery detected ground inflation near South Sister in 2001,
10780-720: The trees. Douglas-fir is dominant below 3,500 ft (1,100 m), while western hemlock dominates above. Timberline at the Three Sisters occurs at 6,500 ft (2,000 m), where the forest canopy opens and the subalpine zone begins. These forests lie in the Cascade Crest montane forest ecoregion . Mountain hemlock trees dominate the forest in this area, while meadows sustain sedges , dwarf willows , tufted hairgrass , lupine , red paintbrush , and Newberry knotweed . Tree line occurs at 7,500 feet (2,300 m). The vegetation in this harsh alpine zone consists of herbaceous and shrubby subalpine meadows. This zone has
10890-517: The volcano stood more than 11,000 ft (3,400 m) high, but erosion reduced this volume by a quarter to a third. The plug is now exposed and forms North Sister's summits at Prouty Peak and the South Horn. Middle Sister, also known as "Hope", is a basaltic stratovolcano that has also erupted more-viscous andesite, dacite, and rhyodacite. The smallest and least studied of the three, Middle Sister began eruptive activity 48,000 years ago, and it
11000-461: The volcano's northern flank, erosion from these glaciers exposed a headwall about 1,200 ft (370 m) high. During the Holocene, smaller glaciers formed, alternating between advance and retreat, depositing moraines and till between 7,000 and 9,000 ft (2,100 and 2,700 m) on the mountain. The Lewis and Clark glaciers have cirques , or glacial valleys, that made the outer walls of
11110-527: The volcano. These relatively recent, postglacial eruptions suggest the presence of a silicic magma reservoir under South Sister, one that could perhaps lead to future eruptions. Unlike its sister peaks, South Sister has an uneroded summit crater about 0.25 mi (0.40 km) in diameter that holds a small crater lake known as Teardrop Pool, the highest lake in Oregon. Its cone consists of basaltic andesite along with red scoria and tephra, with exposed black and red inner walls made of scoria. Hodge Crest,
11220-535: The western half merged in 1934 to form the Willamette National Forest. Most of the Three Sisters glaciers were described for the first time by Ira A. Williams in 1916. Collier Glacier, between North and Middle Sister, was first studied and mapped by Edwin Hodge. Ruth Hopsen Keen took a forty-year photographic record of Collier Glacier, documenting part of the 0.93 mi (1,500 m) retreat of
11330-401: The western slopes, which causes it to cool and dump its moisture as rain (or snow in the winter). Precipitation increases with elevation. Once the moisture is wrung from the air, the air descends on the eastern side of the crest, which causes it to become warmer and drier. On the western slopes, precipitation ranges from 80 to 125 in (200 to 320 centimeters) annually, while precipitation over
11440-418: The youngest Tumalo pyroclastic deposits, indicating that North Sister was active more recently than 260,000 years ago. North Sister, also known as "Faith", is the oldest and most highly eroded of the three, with zigzagging rock pinnacles between glaciers. It is a shield volcano that overlays a more ancient shield volcano named Little Brother. North Sister is 5 mi (8 km) wide, and its summit elevation
11550-724: Was applied to the River of the West based on Native American tales of powerful Chinook winds on the lower Columbia River, or perhaps from first-hand French experience with the Chinook winds of the Great Plains . At the time, the River of the West was thought to rise in western Minnesota and flow west through the Great Plains. Another suggestion comes from Joaquin Miller , who wrote in Sunset magazine in 1904: The name, Oregon,
11660-574: Was delayed several times, as members of Congress argued among themselves whether the territory should be admitted as a "free" or "slave" state. Eventually politicians from the South agreed to allow Oregon to enter as a "free" state, in exchange for opening slavery to the Southwestern U.S. Oregon was admitted to the Union on February 14, 1859, though no one in Oregon knew it until March 15. Founded as
11770-633: Was further explored by John Strong Newberry in 1855 as part of the Pacific Railroad Surveys . In 1862, to connect the Willamette Valley to the ranches of Central Oregon and the gold mines of eastern Oregon and Idaho, Felix and Marion Scott traced a route over Scott Pass. This route was known as the Scott Trail, but was superseded in the early 20th century by the McKenzie Pass Road further north. In February 1866,
11880-553: Was getting overgrazed. Despite regulatory measures, sheep grazing peaked in 1910 before being banned in the 1930s at North and Middle Sister, and in 1940 at South Sister. In 1892, President Grover Cleveland decided to create the Cascades Forest Reserve, based on the authority of the Forest Reserve Act of 1891 . Cascades Reserve was a strip of land from 20 to 60 mi (30 to 100 km) wide around
11990-483: Was primarily built by eruptions occurring between 25,000 and 18,000 years ago. One of the earliest major eruptive events (about 38,000 years ago) produced the rhyolite of Obsidian Cliffs on the mountain's northwestern flank. Thick and rich in dacite, the flows extended from the northern and southern sides. They stand in contrast to older, andesitic lava remains that reach as far as 4.3 mi (7 km) from its base. With an elevation of 10,052 ft (3,064 m),
12100-501: Was the first acting public government of the Oregon Country before annexation by the government of the United States. It was succeeded by a Second Executive Committee, made up of Peter G. Stewart , Osborne Russell , and William J. Bailey , and this committee was itself succeeded by George Abernethy , who was the first and only Governor of Oregon under the provisional government. Also in 1841, Sir George Simpson , governor of
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