South Sister volcano's NE face with stacks of andesite lava flows a...

South Sister volcano's northeast face with stacks of andesite lava ...

Detailed Description

Dipping stacks are truncated at about 3000 m (9,800 ft) elevation, forming ragged rim of a broad paleocrater. Gray, stratified, dacitic phreatomagmatic deposit 150 m thick makes up upper slopes of edifice, capped only by thin ledge of mafic agglutinate on skyline. Beneath Hodge Crest (left shoulder of edifice) is another thick, gray phreatomagmatic deposit, this one cut by many dikes that altered host fallout, which erodes into colorful spires. Little Ice Age moraines in foreground are barren and unstable.


Image Dimensions: 4200 x 2801


Hildreth et al., 2013