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Summary of eruption dates and Volcanic Explosivity Indices (VEI).
|Start Date||Stop Date||Eruption Certainty||VEI||Evidence||Activity Area or Unit|
|5800 BCE ± 1000 years||Unknown||Confirmed||Magnetism||North flank (Egan cone)|
The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.
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.
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.