The north flank of North Sister contains young scoria cones that have produced lava flows during the past few thousand years, seen here covered with light snow. Yapoah cone, the symmetrical snow-covered cone in the center of the photo, produced a lava flow about 2,600-2,900 years ago that traveled beyond the margin of the photo for 13 km to the NE.

Photo by Lee Siebert, 1995 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Keywords: stratovolcano | scoria cone

Three Sisters