Angular unconformity atop Mount Everts, Yellowstone National Park

An unconformity at the top of Mount Everts is located where the Huckleberry Ridge Tuff, 2.1 million years old, lies directly on top of Cretaceous sediments that are ~60 million years old and greater.  Right at the unconformity are conspicuous orange and black colors.  The orange is oxidation of the sedimentary unit where it is in contact with the ash, which was hot when it was deposited.  The black layer is a chilled margin of the ash flow, which cooled quickly upon emplacement.  Canary Spring, part of the Mammoth Hot Springs terraces, lies in the foreground.