Three Sisters (Oregon)

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Coordinates: 44°06′12″N 121°46′09″W / 44.1034490, -121.7692058

Three Sisters

South Sister from the south.
Elevation South  10,363 feet (3,159 m)[1]

Middle 10,047 feet (3,062 m)[2]
North   10,085 feet (3,074 m)[2]
Location Oregon, USA
Range Cascade Range
Prominence South  5,598 feet (1,706 m)[3]

Middle 1,127 feet (344 m)[4]
North   2,725 feet (831 m)[5]
Coordinates South  44°06′12″N 121°46′09″W / 44.1034490, -121.7692058 (South Sister)[6]

Middle 44°08′53″N 121°47′02″W / 44.1481718, -121.7839312 (Middle Sister)[7]
North   44°09′58″N 121°46′21″W / 44.1662273, -121.7725431 (North Sister)[8]
Topo map USGS South Sister and North Sister
Type Stratovolcanoes and shield volcanoes
Volcanic arc/belt Cascade Volcanic Arc
Age of rock Quaternary
Last eruption about 1600 years ago
Easiest route hiking or scrambling, plus glacier travel on some routes

The Three Sisters are three volcanic peaks of the Cascade Volcanic Arc and the Cascade Range in Oregon, each of which exceed 10,000 feet (3,048 m) in elevation. They are the third, fourth, and fifth highest peaks in the state of Oregon and are located in the Three Sisters Wilderness, about 15 mi (24 km) southwest from the nearest town of Sisters, Oregon. The three peaks have 15 named glaciers among them, nearly half of all the 35 named glaciers in Oregon. The Sisters were named Faith, Hope, and Charity by early settlers.[2]

North Sister is the oldest of the three,[9] with towering rock pinnacles and glaciers. It has not erupted since the late Pleistocene.[9] It is the most dangerous climb of the Three Sisters, due to its level of erosion, and thus rockfall.

Middle Sister is the smallest and most poorly studied. It is also the middle in age.[9] No reports on its potential for eruptions have been made.

South Sister is the youngest and tallest volcano of the trio. It is a stratovolcano which last erupted about 1600 years ago.[9] It has an uneroded summit crater about 0.25 mi (0.4 km) in diameter, which holds a small crater lake known as Teardrop Pool which is usually frozen except during the summer. This is the highest lake in Oregon. The standard climbing route up the South Ridge of South Sister is a long, steep, non-technical hike that can be easily completed in a day by reasonably fit hikers. Popular starting points are the Green Lakes or Devil's Lake trailheads.

[edit] Recent history

In 2001 a satellite discovered that there was a deforming uplift 3 miles (4.8 km) south of the South Sister. There was concern that the mountain was awakening. In 2004 an earthquake swarm occurred with the epicenter in the area of uplift. The hundreds of small earthquakes subsided over several days. As of 2007 the uplift had slowed and concern had diminished though the area was still considered potentially active.[10]

[edit] References

  1. ^ NGS Data Sheet for SOUTH SISTER. U.S. National Geodetic Survey. Retrieved on 2008-04-02.
  2. ^ a b c Cascade Volcano Observatory: Three Sisters Volcanoes, Oregon. USGS. Retrieved on 2008-04-02.
  3. ^ South Sister, Oregon. Peakbagger.com. Retrieved on 2008-04-02.
  4. ^ Middle Sister, Oregon. Peakbagger.com. Retrieved on 2008-04-02.
  5. ^ North Sister, Oregon. Peakbagger.com. Retrieved on 2008-04-02.
  6. ^ USGS GNIS: South Sister. Retrieved on 2008-04-02.
  7. ^ USGS GNIS: Middle Sister. Retrieved on 2008-04-02.
  8. ^ USGS GNIS: North Sister. Retrieved on 2008-04-02.
  9. ^ a b c d Sherrod, David R.; Edward M. Taylor, Mark L. Ferns, William E. Scott, Richard M. Conrey, and Gary A. Smith (2004). Geologic Map of the Bend 30-×60-Minute Quadrangle, Central Oregon. U.S. National Geodetic Survey. Retrieved on 2008-04-02.
  10. ^ Three Sisters, Oregon Information Statement. USGS (2007-04-11). Retrieved on 2008-04-02.

[edit] External links
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Major Cascade Volcanoes
British Columbia
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Volcanoes of Oregon
High Cascades
Western Cascades
Eastern Cascades
Basin and Range
Columbia Plateau