The Three Sisters Wilderness is a wilderness area in the Cascade Range, within the Willamette and Deschutes National Forests in Oregon, 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 in 1964 and is named for the Three Sisters volcanoes. The wilderness boundary encloses the Three Sisters as well as Broken Top, which is southeast of South Sister.

Three Sisters was designated as a UNESCO Biosphere Reserve under the Man and the Biosphere Programme in 1976, and was one of 17 reserves in the United States withdrawn from the programme in June 2017.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 to the north, while the Waldo Lake Wilderness shares the southern boundary. 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 features, the most notable being the Cascades which are stratovolcanoes having formed around 1.6 million years ago. Numerous cinder cones have formed on their flanks as well as many lava flows that contain hundreds of lava tubes.

thumb|upright|[[Proxy Falls in the wilderness]]

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 Broken Top—just to the south at — there are 14 glaciers offering one of the best examples of the effects of glaciation in the Pacific Northwest. Collier Glacier, between North and Middle Sister, is the largest glacier in Oregon.) emerge in the Wilderness.

Vegetation

Forest cover in the Three Sisters Wilderness includes Douglas fir, Pacific silver fir, subalpine fir, mountain hemlock, western hemlock, lodgepole pine and ponderosa pine. A large area of the wilderness above timberline contains alpine meadows.

Recreation

thumb|Hikers in the wilderness south of South Sister

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.

See also

thumb|Topographic map of area

  • List of Oregon Wildernesses
  • List of U.S. Wilderness Areas
  • Wilderness Act

References

  • Three Sisters Wilderness - Willamette National Forest
  • Three Sisters Wilderness - Deschutes National Forest
  • Wilderness.net Wilderness information
  • TopoQuest map of the Three Sisters