South Sister volcano, United States
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South Sister volcano, United States
South Sister volcano, reflected in the waters of Sparks Lake, is the highest and youngest of the Three Sisters volcanoes in the central Oregon Cascades.
The summit cone of South Sister has not erupted since the very latest Pleistocene, but the light-colored rocks above the meadow at the left are part of a group of lava flows on the flank that were extruded about 2000 years ago.
South Sister is the highest and youngest of the Three Sisters volcanoes that dominate the landscape of the central Oregon Cascades.
The main edifice of 3157-m-high South Sister is constructed of andesitic and dacitic lava flows capped by a symmetrical summit cinder cone of probable latest-Pleistocene age.
The late Pleistocene or early Holocene Cayuse Crater on the SW flank of Broken Top volcano and other flank vents such as Le Conte Crater on the SW flank of South Sister mark mafic vents that have erupted at considerable distances from South Sister itself.
Late-Holocene eruptions formed a chain of dike-fed rhyodacitic lava domes and flows on the volcano's SE-to-SW flanks about 2000 years ago. Satellite radar interferometry (InSAR) data obtained by U S Geological Survey scientists detected continuing long-term slight uplift of the ground surface over a broad region centered 5 km west of South Sister volcano that began in 1997.
PHOTO SOURCE:Photo by Dave Wieprecht, 1995 (U.S. Geological Survey).
NOTE: The information regarding Volcano on this page is re-published from other sources. No claims are made regarding the accuracy of Volcano information contained here. All suggestions for corrections of any errors about Volcano photos should be addressed to the copyright owner noted below the photo.
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