South Sister volcano viewed northward from east shore of Sparks Lak...

South Sister volcano viewed northward from east shore of Sparks Lak...

Detailed Description

Visible are five rhyolitic units of different ages: Unforested 2-ka rhyolite of "Devils chain" rests on forested 35-ka flow lobe from adjacent Devils Hill dome. Three pale-gray spurs form sharp salients that extend to elevations only 550 m below darker andesitic summit of South Sister. Each spur is a petrographically distinctive rhyolite lava, and they yield ages of (from left to right) 51 ka, 30–24 ka, and 35 ka. On skyline, South Sister summit and Hodge Crest are separated by cirque of Lewis Glacier.

Details

Image Dimensions: 2130 x 1382

Source:


Hildreth et al., 2013