Volcanoes of the Three Sisters region, Oregon Cascades Public Deposited

http://ir.library.oregonstate.edu/concern/defaults/79407z51r

Gerald W. Williams Collection

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  • During Pliocene time a cluster of basaltic and basaltic andesite shield volcanoes was built in the Three Sisters region. Included in this cluster are the North Sister, Little Brother, Husband, Wife, Sphinx and Broken Top, the radial dikes and conduit fillings of which have been laid bare by glacial erosion. The view that this arcuate line of peaks marks the rim of a caldera formed by decapitation of an enormous central volcano, Mount Multnomah, is shown to be erroneous. During the Pleistocene, andesites and dacites were erupted, principally by the Middle and South Sisters, while new basaltic cones were growing elsewhere. During Recent time, still other cones of basaltic lava and scoria were formed and vast flows were poured from some of them, notably from the Belknap Craters near McKenzie Pass, while showers of pumice and viscous domes of obsidian were erupted by neighboring vents. Some of these eruptions ended only a few centuries ago; nowhere in the High Cascades has there been more volcanic activity within the last millennium. Taken as a whole, the magmatic history closely resembles that of the Crater Lake region and the post-Miocene activity of other parts of the Cascade Range farther south.
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  • Master files scanned at 600 ppi (256 Grayscale) using Capture Perfect 3.0 on a Canon DR-9080C in TIF format. PDF derivative scanned at 300 ppi (256 B&W, 256 Grayscale), using Capture Perfect 3.0, on a Canon DR-9080C. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
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  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2009-04-20T23:14:47Z (GMT) No. of bitstreams: 1 Vol_Thr_Sis_Reg_Ore_Cas.pdf: 1504609 bytes, checksum: e161174f5e0d271a8d5022f26eb02d7c (MD5)
  • description.provenance : Made available in DSpace on 2009-04-20T23:14:47Z (GMT). No. of bitstreams: 1 Vol_Thr_Sis_Reg_Ore_Cas.pdf: 1504609 bytes, checksum: e161174f5e0d271a8d5022f26eb02d7c (MD5) Previous issue date: 1944
  • description.provenance : Submitted by Anna Opoien (aoscanner@gmail.com) on 2009-04-18T01:58:56Z No. of bitstreams: 1 Vol_Thr_Sis_Reg_Ore_Cas.pdf: 1504609 bytes, checksum: e161174f5e0d271a8d5022f26eb02d7c (MD5)

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