In the American Southwest, transitions from one ecosystem to another can be dramatic and abrupt. This certainly is true in northern Arizona, where the parched Painted Desert, shown in this enhanced satellite image in a palette of purples, adjoins Sitgreaves National Forest (shades of green), a realm of pine woodlands with abundant wildlife. Within the Painted Desert lie the Hopi Buttes, a field of ancient volcanic cones, seen here as a scattering of dark, circular shapes near the top of the photograph. The Painted Desert's spectacular colors originate with iron and manganese minerals embedded in stratified layers of siltstone, mudstone, and shale. Image courtesy of USGS.