Larch Mountain (Multnomah County, Oregon)

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This article is about the extinct volcano in Multnomah County. For the mountain in the Northern Oregon Coast Range, see Larch Mountain (Washington County, Oregon).
Larch Mountain
Larch Mountain-Oregon from Washough-Washington.JPG
Larch Mountain, as seen from Washougal, Washington.
Elevation 4,061 ft (1,238 m) NAVD 88[1]
Prominence 975 ft (297 m)[2]
Location Multnomah County, Oregon, U.S.
Range Cascades
Coordinates 45°31′58″N 122°05′16″W / 45.532756064°N 122.087797881°W / 45.532756064; -122.087797881Coordinates: 45°31′58″N 122°05′16″W / 45.532756064°N 122.087797881°W / 45.532756064; -122.087797881[1]
Topo map USGS Multnomah Falls
Type Shield volcano[3]
Volcanic field Boring Lava Field
Easiest route paved road (June–October)
hiking trails (November–May)

Larch Mountain is an extinct volcano[4] near Portland, Oregon. The name is misleading, as no western larch (a large deciduous, coniferous tree) can be found there.[5] It received that name when early lumbermen sold the Noble Fir wood as larch. The peak can be reached between May and November on paved Larch Mountain Road, 16 miles (26 km) east of Corbett, Oregon, although the road is closed during the winter and spring months,.[6] From the north side of the large summit parking lot, hiking trails lead around the volcano's caldera to Sherrard Point[7] with an outstanding view of nearby Mount Hood, Mount Adams, Mount Jefferson, Mount Rainier near Seattle and Mount St. Helens, an active volcano. Distance plaques are provided, showing the distance to said volcanoes.[8] Another trail leads 6.8 miles (10.9 km) north to the foot of Multnomah Falls near the Columbia River, visiting many lesser waterfalls along the way, many of which emanate from the mountain.

Larch Mountain is the remnant of an ancient shield volcano, with broad slopes covering tens of square kilometers. It is currently the tallest peak in the Boring Lava Field, a volcanic field active during the Plio-Pleistocene time frame. The volcano is composed mainly of andesites, in contrast to the rest of the region, which is composed of basalt.[9] Sherrard Point at the pinnacle is the eroded remains of the original volcanic plug.[8]


See also[edit]


  1. ^ a b "Larch Reset". NGS data sheet. U.S. National Geodetic Survey. Retrieved 2008-11-18. 
  2. ^ "Larch Mountain, Oregon". Retrieved 2008-04-01. 
  3. ^ "Larch Mountain, Boring Lava Field, Oregon". USGS Cascades Volcano Observatory. Retrieved 2008-04-01. 
  4. ^ Cascades Volcano Observatory (2014-06-11). "The Boring Volcanic Field — Hills of the Portland Basin". USGS. Retrieved 2015-02-21. All existing Boring Volcanic centers are extinct, but the Boring Volcanic Field presumably is not. Since activity started 2.6 million years ago, it is rare that 50,000 years passed without an eruption. The probability of an eruption in the Portland/Vancouver metro area however, is very low. 
  5. ^ Reed, Ione (December 25, 1971). "What, Indeed, Is in a Name?". Eugene Register-Guard. p. 8. Retrieved 30 April 2015. 
  6. ^ "Larch Mountain Picnic Area". United States Forest Service. Retrieved 11 August 2015. 
  7. ^ "Sherrard Point". Geographic Names Information System. United States Geological Survey. Retrieved 2008-11-16. 
  8. ^ a b Hart, Steve (26 February 2015). "Sherrard Point". Retrieved 11 August 2015. 
  9. ^ Evarts, Russell C.; Conrey, Richard M.; Fleck, Robert J.; Hagstrum, Jonathan T. (2010). "The Boring Volcanic Field of the Portland-Vancouver area, Oregon and Washington: Tectonically anomalous forearc volcanism in an urban setting". pp. 253–270. doi:10.1130/2009.fld015(13).