Alaska Volcano Observatory

Oblique aerial view of the summit of Tolsona No. 2 mud volcano, the western-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 view is roughly to the northwest.