The trunks of the large ponderosa pine tree at the left and the smaller birch to the right in the Lost Creek valley NE of Lassen Peak were bent over by a mudflow from an eruption in May 1915. After the eruption vertical growth of the trees resumed. The mudflows traveled 50 km from the volcano, destroying bridges, farmlands, and farm buildings.

Photo by Lee Siebert, 1982 (Smithsonian Institution).

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

Lassen Volcanic Center