South Sister's northwest summit, basaltic andesite lava and scoria cap the volcano.
By Volcano Hazards Program
2007 (approx.)
Detailed Description
Lost Creek Glacier and its cirque are in the center, and Eugene Glacier and its cirque are toward the bottom left. Fingerlike lobes of dacite lava dribble down northwest ridge atop fragmental deposit and beneath capping agglutinate. The entire edifice visible here was built between 30 and 20 ka.
Sources/Usage
Public Domain.
Hildreth et al., 2013
Related
Eruption History for South Sister
South Sister is the southernmost and tallest of the Three Sisters. Early eruptions began between 50 to 45 ka, when South Sister produced numerous rhyolite lava flows and domes. Between 37 and 30 ka, the broad cone was built of rhyolite to andesite domes and flows, and construction of the cone ended with an explosive eruption that left pyroclastic deposi
Related
Eruption History for South Sister
South Sister is the southernmost and tallest of the Three Sisters. Early eruptions began between 50 to 45 ka, when South Sister produced numerous rhyolite lava flows and domes. Between 37 and 30 ka, the broad cone was built of rhyolite to andesite domes and flows, and construction of the cone ended with an explosive eruption that left pyroclastic deposi