Global Volcanism Program | Image GVP-03358
A roadcut at Golden Gate, north of Mammoth, cuts through the Huckleberry Ridge Tuff, the deposit produced by the gigantic eruption that created Yellowstone's first caldera about 2 million years ago. The 2500 cu km Huckleberry Tuff, one of the world's largest Quaternary eruptions, consists of welded tuffs and voluminous airfall deposits found as far away as southern California. The eruption created the 75-km-wide Island Park caldera, which extends from SE-Idaho into central Yellowstone.
Photo by Lee Siebert, 1994 (Smithsonian Institution).
This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.