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The Volcanoes of Lewis and Clark

Mount Jefferson, Oregon
 
Mount Jefferson as seen from Highway 97


Mount Jefferson, Oregon:
Mount Jefferson (10,495 feet) is a prominent feature of the landscape seen from highways east and west of the Cascades. Mount Jefferson is one of thirteen major volcanic centers in the Cascade Range. It has erupted repeatedly for hundreds of thousands of years, with its last eruptive episode during the last major glaciation which culminated about 15,000 years ago.


Eruptive History:
Geologic evidence shows that Mount Jefferson is capable of large explosive eruptions. The largest such eruption occurred between 35,000 and 100,000 years ago, and caused ash to fall as far away as the present-day town of Arco in southeast Idaho. Most of the upper 3,200 feet of Mount Jefferson is less than 100,000 years old, with much of it younger than the explosive event described above. This upper cone is composed largely of dacite lava flows and domes, many of which appear to have been emplaced when glaciers on the volcano were much large than at present. It is likely that during growth of the domes, material was shed off to form pyroclastic flows and lahars, but if so, that record has been largely removed by glacial erosion. The youngest lava flows in the Mount Jefferson area are basaltic lava flows from Forked Butte and an unnamed butte south of Bear Butte. Both of these flows postdate the large eruption of Mount Mazama (Crater Lake) of about 7,600 years.


Recent History:
During the last few centuries, several small lakes were formed on the flanks of Mount Jefferson when small tributary valleys becamed dammed by glacial moraines (ridges of sediment left behind by glaciers). Several of these moraines have breached during the 20th century, producing local floods and small lahars.


Lewis and Clark:
On March 30, 1806, the Lewis and Clark spotted and named Mount Jefferson, after the then current President of the United States who had funded their expedition. " ... we made 22 Miles only to day the wind and a Strong current being against us all day, with rain. discovered a high mountain S E. Covered with Snow which we call Mt. Jefferson ..." [Clark, March 30, 1806]


Map, the Volcanoes of Lewis and Clark, click to enlarge Map, 1814, Lewis and Clark on the Columbia, click to enlarge Map, 1814, Lewis and Clark on the Columbia, click to enlarge Map, 1833, Illman and Pilbrow, Columbia River, click to enlarge Map, 1841, Wilkes, Columbia River with Mounts St. Helens, Hood, and Jefferson, click to enlarge Map, 1849, Alexander Ross's Columbia River, click to enlarge Map, 1853, Washington and Oregon and the Columbia River, click to enlarge Map, 1855, Columbia River, Vancouver to the Pacific, click to enlarge Map, 1855, Columbia River, Cascade Range to Walla Walla, click to enlarge Map, 1860, Columbia River, Washington, Oregon, click to enlarge NASA Image, 1994, Columbia River, Mount Hood, and Mount Jefferson, click to enlarge NASA Image, 1985, Detroit Lake and Mount Jefferson, click to enlarge Image, Mount Jefferson, Oregon, as seen from Highway 97 Image, 2003, Mount Jefferson, Oregon, as seen from Columbia Shores area, Washington Image, 2003, Mount Jefferson, Oregon, from Blurock Landing, Washington Image, 2004, Mount Jefferson, Oregon, as seen from Columbia Shores area, Washington
  1. Map, "Lewis and Clark Volcano Sitings"

  2. 1814 Map, Lewis and Clark's map of the Columbia River (section of original). (Click to enlarge.) Includes three of the five volcanoes Lewis and Clark saw and commented on. While the journals mention the expedition seeing Mount Adams, it does not appear on their map. Mount Jefferson is to the south (bottom) and off the map. From the "Nicholas Biddle/Paul Allen" 1814 publication. Original Map: "A Map of Lewis and Clark's Track, Across the Western Portion of North America, From the Mississippi to the Pacific Ocean". From: History of the expedition under the command of Captains Lewis and Clark : to the sources of the Missouri, thence across the Rocky Mountains and down the river Columbia to the Pacific Ocean : performed during the years 1804-5-6 : by order of the government of the United States / prepared for the press by Paul Allen. Philadelphia : Bradford and Insskeep, 1814. Harold B. Lee Library, Brigham Young University #upbover maps37. -- Brigham Young University, Harold B. Lee Library Website, 2004.

  3. 1814 Map, Lewis and Clark's map of the Columbia River (section of original). (Click to enlarge.) Map includes three of the five volcanoes Lewis and Clark saw and commented on. While the journals mention the expedition seeing Mount Adams, it does not appear on their map. Mount Jefferson is just visible to the south (bottom) and Mount Rainier is to the north but off the map. From the "Nicholas Biddle/Paul Allen" 1814 publication. Original Map: "A Map of Lewis and Clark's Track, Across the Western Portion of North America, From the Mississippi to the Pacific Ocean". From: History of the expedition under the command of Captains Lewis and Clark : to the sources of the Missouri, thence across the Rocky Mountains and down the river Columbia to the Pacific Ocean : performed during the years 1804-5-6 : by order of the government of the United States / prepared for the press by Paul Allen. Philadelphia : Bradford and Insskeep, 1814. Harold B. Lee Library, Brigham Young University #upbover maps37. -- Brigham Young University, Harold B. Lee Library Website, 2004.

  4. 1833 Map (section of original), Columbia River. (Click to enlarge). Includes Mount Hood and Mount Jefferson. Note: Mount Baker is depicted (upper middle) but Mounts Adams, Rainier and St. Helens are missing. The Columbia River is shown as "Oregon River" at its mouth and "Columbia or Oregon R." further inland. "Wappatoo Valley" is labeled. Also shows Fort Clatsop ("F. Clatsop or F. George"), the Willamette River ("Multnomah R."), Sandy River ("Quicksand R."), John Day River ("R.La Page"), Walla Walla River ("Wallwullah R."), Snake River ("Lewis R."), and the Yakima River ("Tapete R."). Original Map: Oregon Territory, 1833. Creator: Illman & Pilbrow, published by Illman & Pilbrow, New York. Comments: Illman & Pilbrow is the engraving firm which copyrighted and published this map, the actual artist is unknown. Washington State University Digital Maps Collection #WSU323. University of Washington Digital Maps Collection #UW104. -- Washington State University Early Washington Maps Digital Collection Website, 2004

  5. 1841 Map (section of original), Columbia River, east. (Click to enlarge). Includes Mount St. Helens, Mount Hood, and Mount Jefferson. Mount Adams is depicted but not named. From Wilkes, 1841, the U.S. Exploring Expedition. -- Washington State University Early Washington Maps Digital Collection Website, 2004

  6. 1849 Map (section of original), Alexander Ross's Columbia River. (Click to enlarge). Original Map: Map of the Columbia to illustrate Ross's adventures. Author: Alexander Ross; Publication Date: 1849; Publisher: London, Smith, Elder and Co., 1849. Washington State University Archives #WSU478. -- Washington State University Early Washington Maps Digital Collection Website, 2004

  7. 1853 Map, Washington and Oregon and the Columbia River, from the Clearwater River to the Snake River and down the Columbia River to the Pacific Ocean (section of original). (Click to enlarge). Includes: Clearwater River (Kooskooski), Lapwai Creek (Lapwai R.), Snake River (Saptin or Lewis R.), Columbia River (Columbia R.), Yakima River (Yakima R.), Walla Walla River (Wallawalla R.), Umatilla River (Umatilla R.), Willow Creek (Quesnells R.), John Day River (John Day's R.), Deschutes River (Fall R.), Willamette River (Willammette R.), and Cowlitz River (Cowlitz R.). Original Map: "Map of California, Oregon, Washington, Utah, and New Mexico (1853)", by Thomas Cowperthwait & Co. Washington State University Archives #WSU22. -- Washington State University Library Collections Website, 2003

  8. 1855 Map, Columbia River from Vancouver to the Pacific (section of original). (Click to enlarge). Includes Mount Rainier, Mount St. Helens, Mount Adams, Mount Hood (depicted but not named), and Mount Jefferson. Original Map: "Map of Oregon and Washington Territories: showing the proposed Northern Railroad route to the Pacific Ocean, by John Disturnell, 1855. University of Washington Archives #UW155. -- University of Washington Library Collections Website, 2002

  9. 1855 Map, Columbia River from Cascade Range to Walla Walla (section of original). (Click to enlarge). Includes Mount Adams, Mount St. Helens, Mount Hood (depicted but not named), and Mount Jefferson. Original Map: "Map of Oregon and Washington Territories: showing the proposed Northern Railroad route to the Pacific Ocean, by John Disturnell, 1855. University of Washington Archives #UW155. -- University of Washington Library Collections Website, 2002

  10. 1860 Map, Columbia River, Washington State, and Oregon (section of original). (Click to enlarge). Original Map: Map of Oregon, Washington, and British Columbia, (1860). This map dates between March 2nd, 1861 (when the Dakota Territory was formed) and March 4th, 1863 (when the Idaho Territory was formed from eastern Washington and western Dakota) Nearing retirement from a thirty year long and rather successful career, S. Augustus Mitchell printed this map showcasing Oregon, the Territory of Washington, and British Columbia. Washington became a territory in 1853, arguing that distances to Willamette Valley kept them from obtaining a voice in the Oregon territorial government. As this map shows, when it split from Oregon proper the Washington territory included parts of Wyoming and Montana and all of Idaho. Territorial government for Idaho would not be approved until 1863. When Mitchell retired he left the business for his son to manage. Washington State University Archives #WSU7. -- Washington State University Archives, 2004

  11. 1994, NASA Image, Columbia River looking north, with Mount Hood and Mount Jefferson (Click to enlarge). View from space - Columbia River, Mount Hood, and Mount Jefferson, north-looking low-oblique photograph, NASA Earth from Space #STS068-262-032. -- NASA Earth from Space Website, 2002

  12. 1985, Detroit Lake, Oregon, with Mount Jefferson in the background. (Click to enlarge). Photograph Date: 1985. -- U.S. Army Corps of Engineers Archives Collection, 2003

  13. Image, Mount Jefferson, Oregon, as seen from Eastern Oregon. (Click to enlarge). Image taken from Highway 97. Photographer: Lyn Topinka. -- USGS Cascades Volcano Observatory Photo Archives, 2004

  14. 2003, Mount Jefferson, Oregon, with Portland International Airport in the foreground. (Click to enlarge). On March 30, 1806, Lewis and Clark named Mount Jefferson. Copyright © 2003 Lyn Topinka, private archives, used with permission.

  15. 2003, Mount Jefferson, Oregon (circled), as seen from Blurock Landing, Washington. (Click to enlarge). Blurock Landing is across the Columbia River from the mouth of the Willamette River, Oregon. From this location on the Columbia River Lewis and Clark spotted five volcanoes. Copyright © 2003 Lyn Topinka, private archives, used with permission.

  16. 2004, Mount Jefferson, Oregon, as seen from the Columbia Shores area, Washington. (Click to enlarge). On March 30, 1806, at this campsite, Lewis and Clark named Mount Jefferson. Copyright © 2004 Lyn Topinka, private archives, used with permission.



Excerpts from: Walder, et.al., 1999
 

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06/29/04, Lyn Topinka