Cascade Range

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The Cascade Range is a mountainous region famous for its chain of tall volcanoes called the High Cascades that run north-south along the west coast of North America from British Columbia to the Shasta Cascade area of northern California. The small part of the range in British Columbia is called the Cascade Mountains.

The Cascades (as they are called for short) are part of the Pacific Ring of Fire, the ring of volcanoes around the Pacific Ocean. All of the known historic eruptions in the contiguous United States have been from Cascade volcanoes. The two most recent were Lassen Peak in 1914 to 1921 and Mount St. Helens in 1980.

Contents

1 History 2 Geography 3 Human uses 4 High Cascades 5 Protected areas 5.1 National parks 5.2 National monuments 6 References

History

Native Americans have inhabited the area for thousands of years and developed their own myths and legends concerning the Cascades. According to some of these tales, Mounts Baker, Jefferson, and Shasta were used as refuge from a great flood. Other stories, such as the Bridge of the Gods tale, had various High Cascades such as Hood and Adams, act as god-like chiefs who made war by throwing fire and stone at each other. St. Helens with its pre-1980 graceful appearance, was regaled as a beautiful maiden for whom Hood and Adams feuded. Native tribes also developed their own names for the High Cascades and many of the smaller peaks.

In the spring of 1792 British navigator George Vancouver entered Puget Sound and started to give English names to the high mountains he saw. Mount Baker was named for Vancouver's third lieutenant, the graceful Mount St. Helens for a famous diplomat, Mount Hood was named in honor of Samuel Hood, 1st Viscount Hood (an admiral of the Royal Navy) and the tallest Cascade, Mount Rainier, is the namesake of Admiral Peter Rainier. Vancouver's expedition did not, however, name the range these peaks belonged to. In 1805 the Lewis and Clark expedition passed through the Cascades by using the Columbia River, which for many years was the only practical way to pass that part of the range. The expedition, and the many settlers and traders that followed, met their last obstacle to their journey at the Cascades Rapids in the Columbia River Gorge, a feature on the river now submerged beneath Lake Bonneville. 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 this name is in the writings of botanist David Douglas). On their return trip Lewis and Clarke's group spotted a high but distant snowy pinnacle that they named for the sponsor of the expedition, U.S. President Thomas Jefferson.

The Barlow Trail was the first established land path for U.S. settlers through the Cascade Range in 1845, and formed the final overland link for the Oregon Trail (previously, settlers had to raft down the treacherous rapids of the Columbia River). It passes north of Mt. Hood.

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 of little-known Mount St. Helens shattered the quiet and brought the world's attention to the range. Geologists were also concerned that the St. Helens eruption would awaken other Cascade volcanoes like it did the previous century, when a total of eight erupted between 1800 and 1857. None have erupted since St. Helens, but precautions are being taken nevertheless, such as the Mount Rainier Volcano Lahar Warning System in Pierce County, Washington.[1] (http://volcanoes.usgs.gov/About/Highlights/RainierPilot/Pilot_highlight.html)

Geography

At its southern end the range is about 30 to 50 miles (50 to 80 km) wide and 4500 to 5000 feet (1370 to 1520 m) high but is higher and 80 miles (130 km) wide in northern Washington. The tallest volcanoes of the Cascades (called the High Cascades) dominate the rest of the range, often standing twice the height of the surrounding mountains and thus often have a visual height of a mile (1.6 km) or more. The tallest peaks, such as the 14,410 foot (4392 m) high Mount Rainier, dominate their surroundings for 50 to 100 miles (80 to 160 km).

The northern part of the range, north of Mount Rainier is extremely rugged, with many of the lesser peaks steep and glaciated. The valleys are quite low however, and major passes are only about 1000 m (3300 ft) high.

Because of the range's proximity to the Pacific Ocean, precipitation is substantial, especially on the western slopes, with annual accumulations of up to 150 inches (3800 mm) in some areas and heavy snowfall as low as 2000 feet (600 m). Most of the High Cascades are therefore white with snow and ice year-round. The western slopes are densely covered with Douglas-fir, Western Hemlock and Red alder, while the drier eastern slopes are mostly Ponderosa Pine, with Western Larch at higher elevations. Annual rainfall drops to 8 inches (200 mm) on the eastern foothills due to a rainshadow effect.

Beyond the foothills is an arid plateau that was created 16 million years ago as a coalescing series of layered flood basalt flows. Together these sequences of fluid volcanic rock form a 200,000 square mile (520,000 km²) region out of western Washington, Oregon, and parts of Northern California and Idaho called the Columbia River Plateau .

The gorge created by the Columbia River is the only major break in the American part of the Cascades. When the Cascades started to rise 7 million years ago in the Pliocene, the Columbia River drained the relatively low Columbia River Plateau. As the range grew, the Columbia was able to keep pace, creating the gorge and major pass seen today. The gorge also exposes uplifted and warped layers of basalt from the plateau.

Another major pass was cut by the Fraser River through mainly non-volcanic rocks in the British Columbian part of the range. This group of mountains are often called the "Coast Mountains" but are in fact structurally part of the Cascades. Mount Garibaldi and its associated group of volcanoes are in this part of the range. The country rocks here were derived from a mini-continent that grafted itself to this part of North America 50 million years ago, carrying along its own subduction zone (see Juan de Fuca Plate).

See also: Map of the Southern Oregon Cascade Range

Human uses

Soil conditions for farming are generally excellent, especially downwind of volcanoes. This is largely due to the fact that volcanic rocks are often rich in minerals such as potassium and decay easily. Volcanic debris, especially lahars, also have a leveling effect and the storage of water in the form of snow and ice is also important. Much of that water eventually flows into reservoirs where it is used for recreation before its potential energy is captured to generate hydroelectric power before being used to irrigate crops.

In addition, there is a largely untapped amount of geothermal power that can be generated from the Cascades. The USGS Geothermal Research Program has been investigating this potential. Some of this energy is already being used in places like Klamath Falls, Oregon where volcanic steam is used to heat public buildings. The highest recorded temperature found in the range is 510° F (265° C) at 3075 feet (937 m) below Newberry Caldera's floor.

High Cascades

(listed north to south)

• Mount Garibaldi (British Columbia) - heavily eroded by glaciers and has three principal peaks.
• Mount Baker (Near the United States-Canada border) - highest peak in northern Washington. It still shows some steam activity from its crater, though it is considered dormant.
• Glacier Peak (northern Washington) - secluded and relatively inaccessible peak. Contrary to its name, its glacial cover isn't that extensive.
• Mount Rainier (southeast of Tacoma, Washington) - highest peak in the Cascades, it dominates the surrounding landscape.
• Mount St. Helens (southern Washington) - Erupted in 1980, completely leveling the surrounding area and sending ash across the northwest. The northern part of the mountain was destroyed in the blast (see 1980 Mount St. Helens eruption).
• Mount Adams (east of Mount St. Helens) - the second highest peak in Washington.
• Mount Hood (northern Oregon) - the highest peak in Oregon and the most frequently climbed major peak in the Cascades.
• Mount Jefferson (northcentral Oregon) - the second highest peak in Oregon.
• Mount Washington (between Santiam and McKenzie passes) [2] (http://areas.wildernet.com/pages/area.cfm?areaname=Mount%20Washington%20Wilderness&CU_ID=144)
• Three Sisters (near the town of Bend, Oregon) - South Sister is the highest and youngest, with a well defined crater. Middle Sister is more pyramidal and eroded. North Sister is the oldest and has a crumbling rock pinnacle.
• Broken Top (to the southeast of South Sister) - contains Bend Glacier
• Newberry Volcano and Newberry Caldera - isolated caldera with two crater lakes. Very variable lavas. Flows from here have reached the city of Bend.
• Mount Bachelor (near Three Sisters) - a popular ski resort.
• Mount Bailey (north of Mount Mazama)
• Mount Thielsen (east of Mount Bailey)
• Mount Mazama (southern Oregon) - detonated thousands of years ago and now known as Crater Lake, which is a caldera formed by a catastrophic eruption which took out most of the summit. Mt. Mazama is estimated to have been about 11,000 ft. elevation prior to the blast.
• Mount McLoughlin (near Klamath Falls, Oregon) - presents a symmetrical appearance when viewed from Klamath Lake.
• Medicine Lake Volcano - a large shield volcano in northern California
• Mount Shasta (northern California) - second highest peak in the Cascades. Can be seen as far as the Sacramento Valley, 60 miles away, as it is a dominating feature of the region.
• Lassen Peak (south of Mt. Shasta) - southernmost volcano in the Cascades and the most easily climbed peak in the Cascades, it erupted 1914-1921

Protected areas

There are four U.S. National Parks in the Cascade Range and many U.S. National Monuments, U.S. National Wilderness Areas, and U.S. National Forests. Each classification protects the various glaciers, volcanoes, geothermal fields, rivers, lakes, and forests to varying degrees.

National parks

• Lassen Volcanic National Park was established in 1916 while its namesake peak was erupting. The park includes the most extensive and active thermal areas in the United States outside Yellowstone National Park.
• Crater Lake National Park preserves the remains of Mount Mazama, a large volcano that imploded thousands of years ago, forming a caldera that was later filled with Crater Lake.
• Mount Rainier National Park surrounds the Cascades' tallest volcano, Mount Rainier, which in turn is shrouded in the largest glacier system in the United States south of Alaska.
• North Cascades National Park was carved out of a primitive part of the range composed of ancient metamorphic and sedimentary rock. Mount Baker and Glacier Peak are nearby.

National monuments

• Mount St. Helens Volcanic National Monument was formed following the 1980 eruption of Mount St. Helens in order to preserve the devastated area and give scientists a chance to study its recovery.

References

• Fire Mountains of the West: The Cascade and Mono Lake Volcanoes, Stephen L. Harris, (Mountain Press Publishing Company, Missoula; 1988) ISBN 0-87842-220-X
• Fred Beckey. 1973. Cascade Alpine Guide (3 vols.) (The Mountaineers, Seattle).
• Stephen L. Harris. 1976. Fire and Ice (The Mountaineers, Seattle).
• USGS: Living With Volcanic Risk in the Cascades (http://wrgis.wr.usgs.gov/fact-sheet/fs165-97/)de:Kaskadengebirge

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