Mount Washington is a 10,000 plus foot high deeply eroded shield volcano in the Cascade Range of Oregon. The mountain dates to the Late Pleistocene. However, it does have a line of basaltic andesite spatter cones on its northeast flank which are approximately 1,330 years old according to carbon dating. The main peak is a volcanic plug that was heavily eroded by glaciers in the last ice age.
Mount Washington was first ascended on August 26, 1923 by Ervin McNeal, Phil Philbrook, Armin Furrer, Wilbur Watkins, Leo Harryman, and Ronald Sellars.