The Three Sisters Wilderness is a

wilderness area Wilderness or wildlands (usually in the plural) are Earth's natural environments that have not been significantly modified by human activity, or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally ...

in the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington (state), Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as m ...

, within the Willamette and

Deschutes National Forest The Deschutes National Forest is a United States national forest (NF) located in Central Oregon, in parts of Deschutes, Klamath, Lake, and Jefferson counties. It was established in 1908, with border changes following in 1911 and 1915. The f ...

s in

Oregon Oregon ( , ) is a U.S. state, 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 (state), Washington, while t ...

, United States. It comprises , making it the second-largest wilderness area in Oregon, after the Eagle Cap Wilderness. It was established by the

United States Congress The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, ...

in 1964 and is named for the Three Sisters volcanoes. The wilderness boundary encloses the Three Sisters as well as

Broken Top 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 ...

, which is southeast of South Sister.Three Sisters Wilderness
- Wilderness.net Three Sisters was designated as a

UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) with the aim of promoting world peace and International secur ...

Biosphere Reserve under the

Man and the Biosphere Programme Man and the Biosphere Programme (MAB) is an intergovernmental scientific program, launched in 1971 by UNESCO, that aims to establish a scientific basis for the 'improvement of relationships' between people and their environments. MAB engages w ...

in 1976, and was one of 17 reserves in the United States withdrawn from the programme in June 2017. Oregon Route 242 separates the Three Sisters Wilderness from the

Mount Washington Wilderness The Mount Washington Wilderness is a National Wilderness Preservation System, wilderness area located on and around Mount Washington (Oregon), Mount Washington in the central Cascade Range of Oregon in the United States. The wilderness was esta ...

to the north, while the

Waldo Lake Wilderness Waldo Lake Wilderness is a wilderness area surrounding Waldo Lake in the central Oregon Cascades. Located within the Willamette National Forest, it was established in 1984 and consists of . Geography Ninety-eight percent of the Waldo Lake ...

shares the southern boundary. The three peaks were known by pioneers as Faith, Hope and Charity. Nearby landmarks include The Husband, The Wife, and the Little Brother.

Geology

Many types of landforms make up the wilderness area, but the most common are

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

features, the most notable being the Cascades which are

stratovolcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...

es having formed around 1.6 million years ago. Numerous

cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...

s have formed on their flanks as well as many

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

s that contain hundreds of

lava tube A lava tube, more rarely called a pyroduct, is a 'roofed conduit through which molten lava travels away from its vent'. If lava in the tube drains out, it will leave an empty cave. Lava tubes are common in low-viscosity volcanic systems. La ...

Topography

The Three Sisters Wilderness ranges in elevation from . The Three Sisters—North Sister at , Middle Sister at , and South Sister at — are found in the eastern portion of the Wilderness. Including

—just to the south at — there are 14 glaciers offering one of the best examples of the effects of

glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...

in the Pacific Northwest. Collier Glacier, between North and Middle Sister, is the largest

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

in Oregon. The headwaters of the Wild and Scenic

Whychus Creek Whychus Creek is a tributary of the Deschutes River in Deschutes and Jefferson counties in the U.S. state of Oregon. Formerly named ''Squaw Creek'', considered derogatory in the 21st century, it was renamed in 2006. Explorer John C. Frémo ...

(formerly Squaw Creek) emerge in the Wilderness.

Climate

Vegetation

Forest cover in the Three Sisters Wilderness includes

Douglas fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is the tallest tree in the Pinaceae family. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Or ...

Pacific silver fir ''Abies amabilis'', commonly known as the Pacific silver fir, is a fir native to the Pacific Northwest of North America, occurring in the Pacific Coast Ranges and the Cascade Range. It is also commonly referred to in English as the white fir, red ...

, subalpine fir,

mountain hemlock ''Tsuga mertensiana'', known as mountain hemlock, is a species of hemlock native to the west coast of North America, found between Southcentral Alaska and south-central California. Description ''Tsuga mertensiana'' is a large evergreen conifer ...

western hemlock ''Tsuga heterophylla'', the western hemlock or western hemlock-spruce, is a species of hemlock native to the northwest coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern ...

lodgepole pine ''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpin ...

and

ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine, is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is t ...

. A large area of the wilderness above timberline contains alpine meadows.Three Sisters Wilderness
- Willamette National Forest

Recreation

Popular recreational activities in the Three Sisters Wilderness include camping, hiking, climbing and fishing. South Sister and Middle Sister are not technically difficult climbs, but summiting North Sister requires technical expertise and equipment. More than of trails cross the wilderness, including of the

Pacific Crest Trail 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 ...

. The French Pete Trail and its surrounding old-growth forest, a nationwide political issue in the 1970s, are located on the western edge of the wilderness near Cougar Reservoir.

References

External links

Three Sisters Wilderness
- Willamette National Forest
Three Sisters Wilderness
- Deschutes National Forest
Wilderness.net Wilderness information

TopoQuest map of the Three Sisters
{{Authority control Former biosphere reserves of the United States Protected areas of Deschutes County, Oregon IUCN Category Ib Protected areas of Lane County, Oregon Wilderness areas of Oregon Willamette National Forest Deschutes National Forest 1964 establishments in Oregon Protected areas established in 1964