Three Fingered Jack

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Three Fingered Jack
Three fingered jack from southwest on PCT P3025.jpeg
Southwest side of Three Fingered Jack seen from Pacific Crest Trail.
Highest point
Elevation 7,844 ft (2,391 m)  NAVD 88[1]
Prominence 2,481 ft (756 m) [2]
Coordinates 44°28′44″N 121°50′35″W / 44.478965122°N 121.843058797°W / 44.478965122; -121.843058797Coordinates: 44°28′44″N 121°50′35″W / 44.478965122°N 121.843058797°W / 44.478965122; -121.843058797[1]
Location Jefferson and Linn counties, Oregon, U.S.[3]
Parent range Cascades
Topo map USGS Three Fingered Jack
Age of rock older than 200,000 years
Mountain type Shield volcano
Volcanic arc Cascade Volcanic Arc
First ascent 1923 by E. McNeal and party[4]

Three Fingered Jack, named for its distinctive shape, is a Pleistocene volcano in the Cascade Range of Oregon. It is a deeply glaciated shield volcano and consists mainly of basaltic andesite lava.[5] Compared with other heavily glaciated volcanic peaks such as Mount Washington and Mount Thielsen, which display eroded volcanic necks, Three Fingered Jack's present summit is a narrow ridge of loose tephra supported by a dike only 10 feet (3.0 m) thick on a generally north–south axis. Radiating dikes and plugs from a series of overlapping cinder and composite cones that support this summit have been exposed by glaciation.[6]

"Jack Glacier" as seen from the Pacific Crest Trail in early Autumn.

The sole glacier is the unofficially-named Jack glacier, located in a shaded cirque on the northeast side at an unusually low altitude for the Oregon Cascades. The last cone-building eruptions were more explosive in nature than earlier shield-building eruptions, producing mostly unconsolidated strata. Cone-building eruptions ceased before the Pleistocene glacial period, allowing the expanded glacial cover to remove most of the cone.[6]

While sources disagree about who the first ascenders were affiliated with, some sources calling them "the Boys from Bend,"[7] others saying they were members of the Mazamas club,[8] one source written by one of these first ascenders clearly states who was in the party and when they climbed. Ervin McNeal, Phil Philbrook, Armin Furrer, Wilbur Watkins, Leo Harryman, and Ronald Sellars were the first to ascend Three Fingered Jack on September 3, 1923.[4]

Three Fingered Jack is located in the Mount Jefferson Wilderness and is not accessible by paved road, but can be approached by the Pacific Crest Trail.[9] It is regarded as extinct and has not been assessed for volcanic hazards.[6]

Several lakes can be found in the vicinity of Three Fingered Jack. These include Marion Lake, Mowich Lake, Duffy Lake, Santiam Lake and Wasco Lake, among others. [10]


A rare herd of mountain goats can be seen on the North face of Three Fingered Jack.
Three Fingered Jack as seen from Santiam Lake.
  1. ^ a b "Three Fingered Jack=Hayrick". NGS data sheet. U.S. National Geodetic Survey. Retrieved 2008-11-17. 
  2. ^ "Three Fingered Jack, Oregon". Retrieved 2008-04-02. 
  3. ^ "Three Fingered Jack". Geographic Names Information System. United States Geological Survey. Retrieved 2008-11-17. 
  4. ^ a b Sellars, Ronald (December 1923). "The Conquest of Mount Washington". Mazama. Portland, OR: Mazamas. 6 (4): 69–75. Retrieved February 18, 2017. 
  5. ^ "Description: Three-Fingered Jack Volcano, Oregon". USGS Cascades Volcano Observatory. Retrieved 2008-04-01. 
  6. ^ a b c Harris, pp. 163–164
  7. ^ Grubbs, p. 68
  8. ^ Thompson, Erwin N. (March 1970). "North Cascades: Basic History Data". National Park Service. Retrieved 2008-08-08. 
  9. ^ Harris, p. 165
  10. ^ "Three Fingered Jack". Retrieved 2016-10-03. 

Works cited[edit]

  • Grubbs, Bruce (1999). Hiking Oregon's Central Cascades. Guilford, Connecticut: Globe Pequot Press. ISBN 1560448733. 
  • Harris, Stephen L. (2005). Fire Mountains of the West: The Cascade and Mono Lake Volcanoes (Third ed.). Missoula, Montana: Mountain Press. ISBN 0-87842-511-X.