The steep summit pinnacle of Mount Jefferson, seen here from the south, is one of the most dramatic summits of a Cascade Range volcano. Jefferson has been inactive since the late Pleistocene, allowing glacial erosion to remove much of the original summit and exposing the more erosion-resistant rocks that cooled slowly in the central conduit.

Photo by Lee Siebert, 1996 (Smithsonian Institution).

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

Keywords: erosion

Jefferson