Global Volcanism Program | Image GVP-03065
The Three Sisters volcanoes form the most prominent landmarks of the central Oregon Cascades. All three volcanoes ceased erupting during the Pleistocene, but flank vents of South Sister to the left and North Sister to the right have erupted in the past few thousand years.
Photo by Lee Siebert, 1995 (Smithsonian Institution).
This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.