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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 43.979°N
  • 121.688°W

  • 2763 m
    9063 ft

  • 322090
  • Latitude
  • Longitude

  • Summit

  • Volcano

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Basic Data

Volcano Number

Last Known Eruption



5800 BCE

2763 m / 9063 ft


Volcano Types

Pyroclastic cone(s)

Rock Types

Andesite / Basaltic Andesite
Basalt / Picro-Basalt

Tectonic Setting

Subduction zone
Continental crust (> 25 km)


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Geological Summary

The 25-km-long Mount Bachelor volcanic chain consists of a symmetrical late-Pleistocene to Holocene stratovolcano SE of South Sister volcano and a roughly N-S-trending chain of scoria cones and small shield volcanoes. The youthful basaltic-andesite and basaltic Mount Bachelor volcanic chain was formed in four eruptive episodes dating back to about 18,000-15,000 years before present (BP). Construction of the NNW-SSE scoria cone chain south of Mount Bachelor was completed by about 12,000 years BP. The 2763-m-high Mount Bachelor (formerly known as Bachelor Butte) on the north topographically dominates the chain and is one of its youngest features. The latest activity from the chain produced early Holocene or latest Pleistocene lava flows on the east side of Sparks Lake erupted from scoria cones on the NNE flank and lava flows from Egan scoria cone on the north flank of Mount Bachelor that slightly preceded the eruption of the Mazama ash from Crater Lake about 7700 years ago.


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Hildreth W E, 2007. Quaternary magmatism in the Cascades--geologic perpectives. U S Geol Surv Prof Pap, 1744: 1-125.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Luedke R G, Smith R L, 1982. Map showing distribution, composition, and age of late Cenozoic volcanic centers in Oregon and Washington. U S Geol Surv Map, I-1091-D.

Peterson N V, Groh E A, 1966. Lunar Geological Field Conference guidebook. Oregon Dept Geol Min Ind, 51 p.

Peterson N V, Groh E A, Taylor E M, Stensland D E, 1976. Geology and mineral resources of Deschutes County Oregon. Oregon Dept Geol Min Ind Bull, 89: 1-62.

Scott W E, Gardner C A, 1992. Geologic map of the Mount Bachelor volcanic chain and surrounding area, Cascade Range, Oregon. U S Geol Surv Misc Invest Ser Map, I-1967, 1:50,000 geol map.

Scott W E, Gardner C A, 1990. Field trip guide to the central Oregon High Cascades, Part 1: Mount Bachelor-South Sister area. Oregon Geol, 52: 99-140.

Scott W E, Gardner C A, Sarna-Wojcicki A M, 1989. Guidebook for field trip to the Mount Bachelor-South Sister-Bend area, central Oregon High Cascades. U S Geol Surv Open-File Rpt, 89-645: 1-68.

Williams H, 1957. A geologic map of the Bend Quadrangle, Oregon and a reconnaissance geologic map of the central portion of the High Cascade Mountains. Oregon Dept Geol Min Ind, 1:125,000 and 1:250,000 scale.

Wood C A, Kienle J (eds), 1990. Volcanoes of North America. Cambridge, England: Cambridge Univ Press, 354 p.

Eruptive History

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
5800 BCE ± 750 years Unknown Confirmed   Magnetism North flank (Egan cone)

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Bachelor Butte


Feature Name Feature Type Elevation Latitude Longitude
Dry Butte Pyroclastic cone 43° 49' 0" N 121° 39' 0" W
Egan Pyroclastic cone 2158 m 44° 0' 0" N 121° 41' 0" W
Klak Butte Pyroclastic cone 43° 52' 0" N 121° 37' 0" W
Kwohl Butte Shield volcano 2243 m 43° 58' 0" N 121° 41' 0" W
Lolah Butte Pyroclastic cone 43° 50' 0" N 121° 41' 0" W
Lolo Butte Pyroclastic cone 43° 51' 0" N 121° 37' 0" W
Lookout Mountain Shield volcano 1894 m 43° 48' 0" N 121° 42' 0" W
Lumrun Butte Pyroclastic cone 43° 50' 0" N 121° 41' 0" W
Pistol Butte Pyroclastic cone 43° 49' 0" N 121° 33' 0" W
Red Crater Pyroclastic cone 1646 m 43° 57' 0" N 121° 47' 0" W
Sheridan Mountain Shield volcano 2100 m 43° 54' 0" N 121° 41' 0" W
Siah Butte Pyroclastic cone 43° 51' 0" N 121° 41' 0" W
Sitkum Butte Pyroclastic cone 43° 50' 0" N 121° 33' 0" W
Three Trappers Pyroclastic cone 43° 50' 0" N 121° 41' 0" W
Tot Mountain Pyroclastic cone 2329 m 43° 57' 0" N 121° 41' 0" W
Wake Butte Pyroclastic cone 43° 50' 0" N 121° 37' 0" W

Photo Gallery

Mount Bachelor, a symmetrical stratovolcano SW of Bend, Oregon, is seen here from the north with a neoglacial moraine in the center. No known summit eruptions have occurred during the Holocene, although Bachelor was active until the latest Pleistocene and a north flank vent produced a series of lava flows that immediately preceded the eruption of the Mazama ash about 6850 years ago.

Photo by Willie Scott, 1981 (U.S. Geological Survey).
Kwohl Butte cinder cone in the foreground is part of a 25-km-long chain of small shield volcanoes and cinder cones extending north to Mount Bachelor. South and Middle Sister volcanoes are visible to the left behind the furrowed slopes of Mount Bachelor.

Photo by Lee Siebert, 1981 (Smithsonian Institution).
Kwohl Butte cinder cone is one in a 25-km-long chain of cinder cones and small shield volcanoes south of Mount Bachelor in the central Cascade Range of Oregon. Despite the youthful appearance of the cone, geologic mapping indicates construction of the chain was completed about 12,000 years ago

Photo by Lee Siebert, 1981 (Smithsonian Institution).
Mount Bachelor, seen here from the jagged summit of Broken Top volcano to the north, is a symmetrical stratovolcano constructed during the latest Pleistocene. The only known Holocene eruptions were from a cone on the north flank. Mount Bachelor is a major downhill skiing destination of the central Oregon Cascades.

Photo by Lee Siebert, 1982 (Smithsonian Institution).
Mount Bachelor, rising 1000 m above Sparks Lake on the west, is a late Pleistocene-to-Holocene basaltic-andesite stratovolcano at the northern end of a 25-km-long chain of scoria cones and small shield volcanoes. The 2763-m-high symmetrical volcano is the site of a major ski resort SW of Bend, Oregon.

Photo by Lee Siebert, 1982 (Smithsonian Institution).

Smithsonian Sample Collections Database

The following 3 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections. Catalog number links will open a window with more information.

Catalog Number Sample Description
NMNH 112584-1 Basalt
NMNH 112584-2 Basalt
NMNH 112584-3 Pumice

Affiliated Sites

Large Eruptions of Bachelor Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
MODVOLC - HIGP MODIS Thermal Alert System Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
MIROVA Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.