TheCascade Range orCascades is a majormountain range of westernNorth America, extending from southernBritish Columbia throughWashington andOregon toNorthern California. It includes both non-volcanic mountains, such as many of those in theNorth Cascades, and the notablevolcanoes known as theHigh Cascades. The small part of the range in British Columbia is referred to as theCanadian Cascades or, locally, as theCascade Mountains. The highest peak in the range isMount Rainier in Washington at 14,411 feet (4,392 m).
Notable volcanoes in the US portion of the Cascades
The Cascades extend northward fromLassen Peak (also known as Mount Lassen) in northernCalifornia to the confluence of theNicola andThompson rivers inBritish Columbia. TheFraser River separates the Cascades from theCoast Mountains in Canada,[4] as does theWillamette Valley from the upper portion of theOregon Coast Range. The highest volcanoes of the Cascades, known as the High Cascades,[5] dominate their surroundings, often standing twice the height of the nearby mountains. They often have a visual height (height above nearby crestlines) of one mile or more. The highest peaks, such as the 14,411-foot (4,392 m) Mount Rainier, dominate their surroundings for 50 to 100 miles (80 to 161 km).
The northern part of the range, north of Mount Rainier, is known as theNorth Cascades in the United States but is formally named the Cascade Mountains north of theCanada–United States border, reaching to the northern extremity of the Cascades atLytton Mountain.[6] Overall, the North Cascades and Canadian Cascades are extremely rugged; even the lesser peaks are steep and glaciated, and valleys are quite low relative to peaks and ridges, so there is great localrelief.[7] The southern part of the Canadian Cascades, particularly theSkagit Range, is geologically and topographically similar to the North Cascades, while the northern and northeastern parts are less glaciated and more plateau-like, resembling nearby areas of theThompson Plateau.[4]
The range is near the Pacific Ocean and in the region'sprevailing westerly winds, so it receives significant rain and snowfall, especially on the western slopes due toorographic lift, with annual snow accumulations of up to 1,000 inches (2,500 cm) (= 83 feet (25 m)) in some areas.Mount Baker in Washington recorded a national record single-season snowfall in the winter of 1998–99 with 1,140 inches (2,900 cm) (= 95 feet (29 m)).[8] Before that year,Mount Rainier held the American record for snow accumulation at Paradise in 1978. It is not uncommon for some places in the Cascades to have over 500 inches (1,300 cm) of annual snow accumulation, such as atLake Helen, near Lassen Peak.[9] Most of the High Cascades are therefore white with snow and ice year-round. The western slopes are densely covered withDouglas-fir (Pseudotsuga menziesii),western hemlock (Tsuga heterophylla) andred alder (Alnus rubra),[10] while the drier eastern slopes feature mostlyponderosa pine (Pinus ponderosa), with somewestern larch (Larix occidentalis),mountain hemlock (Tsuga mertensiana) andsubalpine fir (Abies lasiocarpa) andsubalpine larch (Larix lyallii) at higher elevations.[11] Annual rainfall is as low as 9 inches (230 mm) on the easternfoothills due to arain shadow effect.[12]
TheColumbia Gorge marks where theColumbia River splits the Cascade Range between the states of Washington and Oregon.
Beyond the eastern foothills is anarid plateau that was largely formed 17 to 14 million years ago by the many flows of theColumbia River Basalt Group. Together, these sequences of fluidvolcanic rock form the 200,000-square-mile (520,000 km2)Columbia Plateau in eastern Washington, Oregon, and parts of western Idaho.[13]
TheColumbia River Gorge is the only major break of the range in the United States. When the Cascades began to rise 7 million years ago in the lateMiocene, the Columbia River drained the relatively low Columbia Plateau. As the range grew, erosion from the Columbia River was able to keep pace, carving out the gorge and major pass seen today. The gorge also exposes uplifted and warped layers of basalt from the plateau.[14][15]
Before European exploration, First Nations tribes named many peaks, including "Seekseekqua" forMount Jefferson (Oregon),[16] "M'laiksini Yaina" forMount McLoughlin,[16] "Tahoma", theLushootseed name for Mount Rainier,[17] and "Louwala-Clough", meaning "smoking mountain" for Mount St. Helens.[18]
In early 1792, British navigatorGeorge Vancouver exploredPuget Sound and gave English names to the high mountains he saw. Mount Baker was named for Vancouver's third lieutenant,Joseph Baker, although the first European to see it wasManuel Quimper, who named itla gran montaña del Carmelo ("GreatMount Carmel") in 1790.[19] Mount Rainier was named after AdmiralPeter Rainier. Later in 1792, Vancouver had his lieutenantWilliam Robert Broughton explore the lowerColumbia River. He namedMount Hood afterLord Samuel Hood, anadmiral of theRoyal Navy.Mount St. Helens was sighted by Vancouver in May 1792, from near the mouth of the Columbia River. It was named forAlleyne FitzHerbert, 1st Baron St Helens, a British diplomat.[20] Vancouver's expedition did not, however, name the mountain range which contained these peaks. He referred to it simply as the "eastern snowy range". Earlier Spanish explorers called itSierra Nevada, meaning "snowy mountains".[19]
In 1805, theLewis and Clark Expedition passed through the Cascades on the Columbia River, which for many years was the only practical way to pass that part of the range. They were the first non-indigenous people to seeMount Adams, but they thought it was Mount St. Helens. When they later saw Mount St. Helens they thought it was Mount Rainier.[21] On their return trip, Lewis and Clark spotted ahigh but distant snowy pinnacle that they named for the sponsor of the expedition, U.S. PresidentThomas Jefferson.[22] Lewis and Clark called the Cascade Range the "Western Mountains".[23]
The Lewis and Clark expedition, and the many settlers and traders that followed, met their last obstacle to their journey at theCascades Rapids in the Columbia River Gorge, a feature on the river now submerged beneath theBonneville Reservoir. Before long, the great white-capped mountains that loomed above the rapids were called the "mountains by the cascades" and later simply as the "Cascades". The earliest attested use of the name "Cascade Range" is in the writings of botanistDavid Douglas in 1825.[24][25]
In 1814,Alexander Ross, a fur trader with theNorth West Company, seeking a viable route across the mountains, explored and crossed the northern Cascades betweenFort Okanogan and Puget Sound. His report of the journey is vague about the route taken. He followed the lowerMethow River into the mountains. He might have usedCascade Pass to reach theSkagit River. Ross was the first European-American to explore the Methow River area and likely the first to explore theStehekin River and Bridge Creek region. Due to the difficulty of crossing the northern Cascades and the paucity of beaver, fur-trading companies made only a few explorations into the mountains north of the Columbia River after Ross.[26]
Exploration and settlement of the Cascades region by Europeans and Americans was accelerated by the establishment of a major trading post of theHudson's Bay Company (HBC) atFort Vancouver near today'sPortland, Oregon. From this base HBC trapping parties traveled throughout the Cascades in search of beaver and other fur-bearing animals. For example, using what became known as theSiskiyou Trail, Hudson's Bay Company trappers were the first non-natives to explore the southern Cascades in the 1820s and 1830s, establishing trails which passed nearCrater Lake,Mount McLoughlin,Medicine Lake Volcano,Mount Shasta, and Lassen Peak.[27]
The course of political history in thePacific Northwest saw the spine of the Cascade Range being proposed as a boundary settlement during theOregon Dispute of 1846. The United States rejected the proposal and insisted on the49th parallel north, which cuts across the range just north of Mount Baker. Throughout the period of dispute and up to the creation of theCrown Colony of British Columbia in 1858, the Hudson's Bay Company'sYork Factory Express route, as well the route of fur brigades, followed the Okanogan River along the east edge of the Cascades and the Columbia River through the range. Passes across the range were not well known and little used.Naches Pass was used for driving cattle and horses toFort Nisqually.Yakima Pass was also used by the Hudson's Bay Company.[28]
American settlement of the flanks of the Coast Range did not occur until the early 1840s, at first only marginally. Following theOregon Treaty the inward flux of migration from theOregon Trail intensified and the passes and back-valleys of what is now the state of Washington were explored and populated, and it was not long after that railways followed. Despite its being traversed by several major freeways and rail lines, and its lower flanks subjected to major logging in recent decades, large parts of the range remain intense and forbidding alpine wilderness. Much of the northern half of the Cascades, from Rainier north, have been preserved byU.S. national or British Columbiaprovincial parks (such asE.C. Manning Provincial Park), or other forms of protected area.[29]
The Canadian side of the range has a history that includes theFraser Canyon Gold Rush of 1858–60 and its famousCariboo Road, as well as the older Hudson's Bay Company Brigade Trail from the Canyon to the Interior, the Dewdney Trail, and older routes which connected east to theSimilkameen andOkanagan valleys.
TheBarlow Road was the first established land path for U.S. settlers through the Cascade Range in 1845, and formed the final overland link for theOregon Trail (previously, settlers had to raft down thetreacherous rapids of the Columbia River). The Road left the Columbia at what is nowHood River and passed along the south side of Mount Hood at what is nowGovernment Camp, terminating in Oregon City. There is an interpretive site there now at "The End of The Oregon Trail". The road was constructed as a toll road – $5 per wagon – and was very successful.
In addition, theApplegate Trail was created to allow settlers to avoid rafting down the Columbia River. The Trail used the path of theCalifornia Trail to north-centralNevada. From there, the Trail headed northwest into northern California, and continued northwest towards today'sAshland, Oregon. From there, settlers would head north along the established Siskiyou Trail into theWillamette Valley.
With the exception of the 1915 eruption of remote Lassen Peak in Northern California, the range was quiet for more than a century. Then, on May 18, 1980, the dramatic eruption ofMount St. Helens shattered the quiet and brought the world's attention to the range. Geologists were also concerned that the St. Helens eruption was a sign that long-dormant Cascade volcanoes might become active once more, as in the period from 1800 to 1857 when a total of eight erupted. None have erupted since St. Helens, but precautions are being taken nevertheless, such as theCascades Volcano Observatory and Mount Rainier VolcanoLahar Warning System inPierce County, Washington.[30]
The Cascade Range is made up of a band of thousands of very small, short-lived volcanoes that have built a platform of lava and volcanic debris. Rising above this volcanic platform are a few strikingly large volcanoes, like Mount Hood and Mount St. Helens, that dominate the landscape.[31]
The Cascade volcanoes define the Pacific Northwest section of theRing of Fire, an array of volcanoes that rim the Pacific Ocean. The Ring of Fire is also known for its frequent earthquakes. The volcanoes and earthquakes arise from a common source, namelysubduction. In this case, the denseJuan de Fuca Plate plunges beneath theNorth American Plate at theCascadia subduction zone.[32] As theoceanic slab sinks deep into the Earth's interior beneath the continental plate, high temperatures and pressures allow water molecules locked in the minerals of solid rock to escape. The water rises into the pliable mantle above the subducting plate, causing some of the mantle to melt. This newly formed magma rises toward the Earth's surface to erupt, forming a chain of volcanoes (the Cascade Volcanic Arc) above the subduction zone.[32]
Soil conditions for farming are generally good, especially downwind ofvolcanoes. This is largely because volcanic rocks are often rich inpotassium-bearing minerals such asorthoclase, and erode relatively easily. Volcanic debris, especiallylahars, also helps to spread mineral-rich volcanic material, and the storage of water in the form of snow and ice is also important for agriculture. The snow-capped mountains, such as Mt. Hood andMt. Bachelor, are used asski resorts in the late winter, while in the summer they become popularhiking andmountaineering locations. Much of their meltwater eventually flows into reservoirs, where it is used for recreation, while its potential energy is captured to generatehydroelectric power before the water is used toirrigate crops.
The Cascades harbor a largely-untapped potential forgeothermal power. TheU.S. Geological Survey Geothermal Research Program has been investigating this potential. Some of this energy is already being used in places likeKlamath Falls, Oregon, where volcanic steam is used to heat public buildings.[33] The highest recorded underground temperature found in the range is 510 °F (266 °C) at 3,075 feet (937 m) belowNewberry Volcano'scaldera floor.
Forests of large, coniferous trees (western red cedars, Douglas-firs, western hemlocks,firs,pines,spruces, and others) dominate most of the Cascade Range. Cool, wet winters and warm, dry summers (largely a result of oceanic influence) favor evergreen species, whereas mild temperatures and rich soils promote fast and prolonged growth.[34][35]
Silver fir predominates above 2500 ft, while there aremoors,meadows, andmountain hemlock/subalpine fir groves from 4500 to 6000 ft on the west side. Thetreeline is at ~6000 feet. On the east side, subalpine forests oflarch trees grade topine and interiorfir forests below 4200 ft, which grade toponderosa below 2500 ft, which in turn grades to semidesertscrub near sea level. Above 7500 ft, the landscape is barren with either no plants or onlymoss andlichen.[37]
^Straub, Kristen; Link, Paul."Columbia River Basalt Province".Digital Geology of Idaho. Idaho State University. Archived fromthe original on October 23, 2013. RetrievedNovember 3, 2013.
^Harrison, John (October 31, 2008)."Columbia River Gorge".Columbia River History. Northwest Power and Conservation Council. RetrievedNovember 9, 2013.
Beckey, Fred W. (2003).Range of Glaciers: the Exploration and Survey of the Northern Cascade Range. Portland, Oregon: Oregon Historical Society Press.ISBN978-0-87595-243-7.
Beckey, Fred W. (2008).Cascade Alpine Guide: Climbing and High Routes Rainy Pass to Fraser River. Seattle, Washington: The Mountaineers Books.ISBN978-1-59485-136-0.
Duffell, Stanley; McTaggart, Kenneth Cunningham (1951).Ashcroft Map-Area, British Columbia. Memoir (Geological Survey of Canada). Vol. 262. Ottawa, Ontario: Natural Resources Canada; E. Cloutier, King's Printer.OCLC3333133.
Ernst, Wallace Gary (2000).Earth Systems: Processes and Issues. Cambridge, England: Cambridge University Press.ISBN978-0-521-47323-1.
Harris, Stephen L. (2005).Fire Mountains of the West: The Cascade and Mono Lake Volcanoes (3rd ed.). Missoula, Montana: Mountain Press Publishing Company.ISBN978-0-87842-511-2.
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