Alaska Volcano Observatory

Oblique aerial view of Shepard mud volcano, the eastern-most of the Tolsona group of mud volcanoes located along the Glenn Highway west of Glennallen. The Tolsona Group mud volcanoes emit mostly methane, differing from the Klawasi Group mud volcanoes east of Glennallen, which emit mostly carbon dioxide. The Shepard mud volcano has been dormant since at least the 1940s. The view is roughly to the southwest.