Cascade Range in the context of Shasta County, California

Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial factor in shaping plant community, biodiversity, metabolic processes and ecosystem dynamics for montane ecosystems. Dense montane forests are common at moderate elevations, due to moderate temperatures and high rainfall. At higher elevations, the climate is harsher, with lower temperatures and higher winds, preventing the growth of trees and causing the plant community to transition to montane grasslands and shrublands or alpine tundra. Due to the unique climate conditions of montane ecosystems, they contain increased numbers of endemic species. Montane ecosystems also exhibit variation in ecosystem services, which include carbon storage and water supply.

Mount Rainier (/reɪ.ˈnɪər/ ray-NEER), also known as Tahoma, is a large active stratovolcano in the Cascade Range of the Pacific Northwest in the United States. The mountain is located in Mount Rainier National Park about 59 miles (95 km) south-southeast of Seattle. At around 14,000 feet (4,400 m) it is the highest mountain in the U.S. state of Washington, the most topographically prominent mountain in the contiguous United States, and the tallest in the Cascade Volcanic Arc.

Due to its high probability of an eruption in the near future and proximity to a major urban area, Mount Rainier is considered one of the most dangerous volcanoes in the world, and it is on the Decade Volcano list. The large amount of glacial ice means that Mount Rainier could produce massive lahars that could threaten the entire Puyallup River valley and other river valleys draining Mount Rainier, including the Carbon, White, Nisqually, and Cowlitz (above Riffe Lake). According to the United States Geological Survey's 2008 report, "about 80,000 people and their homes are at risk in Mount Rainier's lahar-hazard zones."

Broken Top is a glacially eroded complex stratovolcano. It lies in the Cascade Volcanic Arc, part of the extensive Cascade Range in the U.S. state of Oregon. Located southeast of the Three Sisters peaks, the volcano, residing within the Three Sisters Wilderness, is 20 miles (32 km) west of Bend, Oregon, in Deschutes County. Eruptive activity stopped roughly 100,000 years ago, and erosion by glaciers has since reduced the volcano's cone to where its contents are exposed. There are two named glaciers on the peak, Bend and Crook Glacier.

Diverse species of flora and fauna inhabit the area, which is subject to frequent snowfall, occasional rain, and extreme temperature variation between seasons. Broken Top and its surrounding area constitute popular destinations for hiking, climbing, and scrambling.

White Mountain Peak (or simply White Mountain), at 14,252 feet (4,344 m), is the highest peak in the White Mountains of California, the highest peak in Mono County, and the third highest peak in the state after Mount Whitney and Mount Williamson. In spite of its name, the summit block of the peak has large swaths of very dark and colorful orange scree and rock; it is composed of Mesozoic metavolcanic rock, which is igneous rock altered by rising granite.

It is the fourteenth most topographically prominent peak in the contiguous United States. White Mountain Peak is one of only two fourteeners (peaks above 14,000 feet) in California that are not in the Sierra Nevada, the other being Mount Shasta at the far northern end of the state in the Cascade Range. It is the only fourteener in the contiguous United States that is not in the Rocky Mountains, the Cascade Range, or the Sierra Nevada. It is in the Inyo-White Mountains.

Rock flour, or glacial flour, consists of fine-grained, silt-sized particles of rock, generated by mechanical grinding of bedrock by glacial erosion or by artificial grinding to a similar size. Because the material is very small, it becomes suspended in meltwater making the water appear cloudy, which is sometimes known as glacial milk.

When the sediments enter a river, they turn it grey, light brown, iridescent blue-green, or milky white. If the river flows into a glacial lake, the lake may appear turquoise in colour as a result. When appearing as any shade of blue, the colour is most commonly caused by the Tyndall Effect, with the particular hue determined by suspended particle size. When flows of the flour are extensive, a distinct layer of a different colour flows into the lake and begins to dissipate and settle as the flow extends from the increase in water flow from the glacier during snow melts and heavy rain periods. Examples of this phenomenon may be seen at Lake Pukaki and Lake Tekapo in New Zealand, Lake Louise, Moraine Lake, Emerald Lake, and Peyto Lake in Canada, Gjende lake in Norway, and several lakes (among others, Nordenskjöld and Pehoé) in Chile's Torres del Paine National Park, and many lakes in the Cascade Range of Washington State (including Diablo Lake, Gorge Lake, and Blanca Lake).

The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch 3,000 mi (4,800 km) in a straight-line distance from the northernmost part of Western Canada, to New Mexico in the Southwestern United States. Depending on differing definitions between Canada and the U.S., its northern terminus is located either in northern British Columbia's Terminal Range south of the Liard River and east of the Trench, or in the northeastern foothills of the Brooks Range/British Mountains that face the Beaufort Sea coasts between the Canning River and the Firth River across the Alaska–Yukon border. Its southernmost point is near the Albuquerque metropolitan area, adjacent to the Rio Grande rift, and north of the Sandia–Manzano Mountain Range, also near Santa Fe, New Mexico. Being the easternmost portion of the North American Cordillera, the Rockies are distinct from the tectonically younger Cascade Range and Sierra Nevada, which both lie farther to its west.

The Rockies formed 55 million to 80 million years ago during the Laramide orogeny, in which a number of plates began sliding underneath the North American plate. The angle of subduction was shallow, resulting in a broad belt of mountains running down western North America. Since then, further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks and valleys. At the end of the last ice age, humans began inhabiting the mountain range. After explorations of the range by Europeans, such as Sir Alexander Mackenzie, and Anglo-Americans, such as the Lewis and Clark Expedition, natural resources such as minerals and fur drove the initial economic exploitation of the mountains, although the range itself has never experienced a dense population.

Mount Mazama (Klamath: Tum-sum-ne) is a complex volcano in the western U.S. state of Oregon, in a segment of the Cascade Volcanic Arc and Cascade Range. The volcano is in Klamath County, in the southern Cascades, 60 miles (97 km) north of the Oregon–California border. Its collapse, due to the eruption of magma emptying the underlying magma chamber, formed a caldera that holds Crater Lake (Giiwas in the Native American language Klamath). Mount Mazama originally had an elevation of approximately 12,000 feet (3,700 m), but following its climactic eruption this was reduced to 8,157 feet (2,486 m). Crater Lake is 1,943 feet (592 m) deep, the deepest freshwater body in the U.S. and the second deepest in North America after Great Slave Lake in Canada.

Mount Mazama formed as a group of overlapping volcanic edifices such as shield volcanoes 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 12,000-foot (3,700 m) height by about 1 mile (1,600 m). Much of the edifice fell into the volcano's partially emptied neck and magma chamber, creating a caldera. The region's volcanic activity results from the subduction of the offshore oceanic plate, and is influenced by local extensional faulting. Mazama is dormant, but the U.S. Geological Survey says eruptions on a smaller scale are likely, which would pose a threat to its surroundings.

The Northwestern United States, also known as the American Northwest or simply the Northwest, is an informal geographic region of the United States. The region consistently includes the states of Oregon, Washington, Idaho, Montana and Wyoming. Some sources include Southeast Alaska in the Northwest. The related but distinct term Pacific Northwest generally excludes areas from the Rockies eastward, whereas the term "Inland Northwest" excludes areas west of the Cascades.

The Northwestern United States is a subportion of the Western United States (which is, itself, even more ambiguous). In contrast, states included in the neighboring regions (Southwestern United States and Great Plains) and Utah are not simultaneously considered part of both regions.

Northern California (commonly shortened to NorCal) is a geocultural region that comprises the northern portion of the U.S. state of California, spanning the northernmost 48 of the state's 58 counties. Northern California in its largest definition is determined by dividing the state into two regions, the other being Southern California. The main northern population centers include the San Francisco Bay Area (anchored by the cities of San Jose, San Francisco, and Oakland), the Greater Sacramento area (anchored by the state capital Sacramento), the Redding, California, area south of the Cascade Range, and the Metropolitan Fresno area (anchored by the city of Fresno). Northern California is coterminous with the natural range of the coast redwood and the giant sequoia, with many well-known old-growth forests and smaller groves. It contains most of the Sierra Nevada, including Yosemite Valley and part of Lake Tahoe, Mount Shasta (the second-highest peak in the Cascade Range after Mount Rainier in Washington), and most of the Central Valley, one of the world's most productive agricultural regions. Northern California is also home to Silicon Valley, the global headquarters for several of the largest most powerful companies in the world, including Alphabet Inc. (Google), Apple, Meta, and Nvidia.

The Northern California Megaregion, one of the 11 megaregions of the United States is centered in Northern California, and extends from Metropolitan Fresno north to Greater Sacramento, and from the Bay Area east across the Nevada state line to encompass the entire Lake Tahoe–Reno area.

Mount Hood, also known as Wy'east, is an active stratovolcano in the Cascade Range and is a member of 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 50 miles (80 km) east-east-southeast of Portland, on the border between Clackamas and Hood River counties, and forms part of the Mount Hood National Forest. Much of the mountain outside the ski areas is part of the Mount Hood Wilderness. With a summit elevation of 11,249 feet (3,429 m), it is the highest mountain in the U.S. state of Oregon and is the fourth highest in the Cascade Range. Ski areas on the mountain include Timberline Lodge ski area which offers the only year-round lift-served skiing in North America, Mount Hood Meadows, Mount Hood Skibowl, Summit Ski Area, and Cooper Spur ski area. Mt. Hood attracts an estimated 10,000 climbers a year.

The peak is home to 12 named glaciers and snowfields. Mount Hood is considered the Oregon volcano most likely to erupt. The odds of an eruption in the next 30 years are estimated at between 3 and 7%, so the U.S. Geological Survey (USGS) characterizes it as "potentially active", but the mountain is informally considered dormant.

The Pacific Crest Trail (PCT), officially designated as the Pacific Crest National Scenic Trail, is a long-distance hiking and equestrian trail closely aligned with the highest portion of the Cascade and Sierra Nevada mountain ranges, which lie 100 to 150 miles (160 to 240 km) east of the U.S. Pacific coast. The trail's southern terminus is next to the Mexico–United States border, just south of Campo, California, and its northern terminus is on the Canada–US border, upon which it continues unofficially to the Windy Joe Trail within Manning Park in British Columbia; it passes through the states of California, Oregon, and Washington.

The Pacific Crest Trail is 2,653 mi (4,270 km) long and ranges in elevation from roughly 110 feet (34 m) above sea level near the Bridge of the Gods on the Oregon–Washington border to 13,153 feet (4,009 m) at Forester Pass in the Sierra Nevada. The route passes through 25 national forests and 7 national parks. Its midpoint is near Chester, California (near Mt. Lassen), where the Sierra and Cascade mountain ranges meet. The overall elevation gain for the Pacific Crest Trail is approximately 489,000 ft (149,000 m).

Johnson Creek is a 25-mile (40 km) tributary of the Willamette River in the Portland metropolitan area of the U.S. state of Oregon. Part of the drainage basin of the Columbia River, its catchment consists of 54 square miles (140 km) of mostly urban land occupied by about 180,000 people as of 2012. Passing through the cities of Gresham, Portland, and Milwaukie, the creek flows generally west from the foothills of the Cascade Range through sediments deposited by glacial floods on a substrate of basalt. Though polluted, it is free-flowing along its main stem and provides habitat for salmon and other migrating fish.

Prior to European settlement, the watershed was heavily forested and was used by Native Americans of the Chinook band for fishing and hunting. In the 19th century, non-Native American settlers cleared much of the land for farming, and the stream is named for one of these newcomers, William Johnson, who in 1846 built a water-powered sawmill along the creek. By the early 20th century, a rail line parallel to the stream encouraged further residential and commercial development. As urban density increased in the floodplain, seasonal floods grew more damaging. In the 1930s the Works Progress Administration of the federal government lined the lower 15 miles (24 km) of Johnson Creek with rock to control the floods. Despite this, the creek flooded 37 times between 1941 and 2006. Since the 1990s, regional planners have tried to reduce flooding by controlling stormwater runoff, creating stream meanders, reducing erosion, replacing impervious surfaces, and protecting riparian buffers.

Mount Rainier National Park (/reɪ.ˈnɪər/ ray-NEER) is a national park of the United States located in southeast Pierce County and northeast Lewis County in the U.S. state of Washington. The park was established on March 2, 1899, as the fourth national park in the United States, preserving 236,381 acres (369.3 sq mi; 956.6 km) including all of Mount Rainier, a 14,410-foot (4,390 m) stratovolcano. The mountain rises abruptly from the surrounding land with elevations in the park ranging from 1,600 feet to over 14,000 feet (490–4,300 m). The highest point in the Cascade Range, Mount Rainier is surrounded by valleys, waterfalls, subalpine meadows, and 91,000 acres (142.2 sq mi; 368.3 km) of old-growth forest. More than 25 glaciers descend the flanks of the volcano, which is often shrouded in clouds that dump enormous amounts of rain and snow.

The park has several entrances that lead to three general areas: Paradise, the Carbon River and Mowich Lake area, and Sunrise. It had over 1.6 million visitors in 2024. Mount Rainier is circled by the Wonderland Trail and is covered by glaciers and snowfields totaling about 35 square miles (91 km). Carbon Glacier is the largest glacier by volume in the contiguous United States, while Emmons Glacier is the largest glacier by area. Mount Rainier is a popular peak for mountaineering with some 10,000 attempts per year with approximately 50% making it to the summit.

The Cascade Volcanoes (also known as the Cascade Volcanic Arc or the Cascade Arc) are a number of volcanoes in a continental volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 miles (1,100 km). The arc formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River which is the northward limit of the Cascade Range proper.

Some of the major cities along the length of the arc include Portland, Seattle, and Vancouver, and the population in the region exceeds 10 million. All could be potentially affected by volcanic activity and great subduction-zone earthquakes along the arc. Because the population of the Pacific Northwest is rapidly increasing, the Cascade volcanoes are some of the most dangerous, due to their eruptive history and potential for future eruptions, and because they are underlain by weak, hydrothermally altered volcanic rocks that are susceptible to failure. Consequently, Mount Rainier is one of the Decade Volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) as being worthy of particular study, due to the danger it poses to Seattle and Tacoma. Many large, long-runout landslides originating on Cascade Volcanoes have engulfed valleys tens of kilometers from their sources, and some of the areas affected now support large populations.

The Nisqually River /nɪˈskwɑːli/ is a river in west central Washington in the United States, approximately 81 miles (130 km) long. It drains part of the Cascade Range southeast of Tacoma, including the southern slope of Mount Rainier, and empties into the southern end of Puget Sound. Its outlet was designated in 1971 as the Nisqually Delta National Natural Landmark.

The Nisqually River forms the Pierce–Lewis county line, as well as the boundary between Pierce and Thurston counties.

The Cowlitz River is a river in the state of Washington in the United States, a tributary of the Columbia River. Its tributaries drain a large region including the slopes of Mount Rainier, Mount Adams, and Mount St. Helens.

The Cowlitz has a 2,586-square-mile (6,698 km) drainage basin, located between the Cascade Range in eastern Lewis County, Washington and the cities of Kelso and Longview. The river is roughly 105 miles (169 km) long, not counting tributaries.