The Painted Desert area is covered by the "Chinle formation", a very soft layer of earth consisting mainly of mud, sandstone, and volcanic ash. The softness allows for fantastic erosion effects as well as colorful staining by mineralized water flows and mineral deposits over the eons. As the Painted Desert erodes, the fossilized artifacts from the Triassic era (220 million years ago) become exposed, most notably the remains of an ancient conifer forest.
