DESCRIPTION:
Mount Bailey and Vicinity, Oregon

[Map,23K,InlineGIF]
Map, Southern Oregon Cascades
-- Modified from: Hoblitt, et.al., 1987, USGS Open-File Report 87-297

Mount Bailey is the southernmost volcano in a north-south-trending volcanic chain 10 kilometers long that rises west of Diamond Lake. Bailey is about the same age as Diamond Peak, 43 kilometers north: less than 100,000 years but greater than 11,000 years old, on the basis of glacial evidence and morphologic comparisons with dated volcanoes. Like Diamond Peak, Bailey consists of a tephra cone surrounded by basaltic andesite lava. Bailey is slightly smaller (8-9 cubic kilometers) than Diamond Peak, and minor andesite erupted from the summit cone in its late stages, whereas Diamond Peak eruptions were never more siliceous than basaltic andesite.

The Mount Bailey chain includes Rodley Butte and other cinder cones to the north, all of which are similar in age (based on morphology) and magmatically related (on the basis of mineralogy, chemistry, and close spatial association of the vents). Volcanism along the Bailey chain migrated spatially from north to south while it evolved chemically. Basaltic andesite (55% SiO2) was erupted from the vents north of Rodley Butte, whereas basaltic andesite and finally andesite (58-59% SiO2) were erupted from the Mount Bailey volcano. ...

Several large basaltic shield volcanoes along the range (High Cascade Range) have steep-sided summit cones, such as Three-Fingered Jack, Mount Washington and North Sister, Mount Bachelor, Diamond Peak, Mount Bailey, and Mount Thielsen, and Mount McLoughlin. A few of these volcanoes contain rocks as silicic as andesite and may have been constructed during several eruptive episodes. These peaks rival the major composite cones in size but contrast with them in origin and structure. Most are composed of central scoria and tuff cones intruded by numerous dikes and one or more plugs. Thin lava flows intertongue with the scoria and mantle the central cone, and more voluminous lava flows typically extend beyond the base of the central cone. No evidence suggests that these volcanoes formed during highly explosive eruptions. Most lava flows and thick tephra-fall deposits are restricted within a few kilometers of vents, and scoriaceous tephras are typically not traceable farther than 20 kilometers from vents.

Mount Bailey, (Diamond Lake Ranger District; Umpqua National Forest) While the current name is not of Native American origin, (actually, this mountain was originally know as Old Baldy, and was probably mistakenly wrote down as Old Bailey), this mountain was known as Youxlokes to the Klamath, which meant "Medicine Mountain". According to legend, medicine men and priests often feasted on the summit and communed with the upper world.

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