Fishlake National Forest, Piute County, Utah
Photographer: Tyler Knudsen
Storm clouds gather over Mount Belknap (12,137 feet) in the Tushar Mountains, Utah’s third-highest range. The smooth, rounded slopes of this summit ridge are composed of easily eroded volcanic ash and lava flows. The mountains are part of the eruptive center of the Marysvale volcanic field, an area of intense volcanic activity between 32 and 22 million years ago.
San Rafael Swell, Sevier County
Photographer: Robert F. Biek
Alluvial and wind-blown sediment partly conceals the Jurassic-age Entrada Sandstone in the Last Chance Desert, which occupies the axis of the Last Chance anticline. The narrow, jagged, black ridge at the center of the photo is a basaltic dike of probable late Tertiary age (3 to 5 million years old) that intrudes the Entrada Sandstone.
Arches National Park, Grand County
Photographer: William Lund
Delicate Arch is formed of Jurassic-age sandstone—the Slick Rock Member of the Entrada Sandstone (base and pedestals) and Moab Member of the Curtis Formation (bridge). With a horizontal span of 32 feet and a vertical span of 46 feet, Delicate Arch is small compared to many other natural arches, but its free-standing nature makes it unique in the world and emblematic of Utah’s spectacular red-rock geology.
Head of Sinbad, San Rafael Swell, Emery County
Photographer: J. Buck Ehler
Dutchman Arch guards the path to Devil’s Racetrack, a popular recreation trail in the San Rafael Swell. Named after a local Dutch cattleman, the arch is composed of the Jurassic-age Wingate Sandstone deposited in ancient sand dunes.
Little Cottonwood Canyon, Wasatch Range, Salt Lake County
Photographer: Valerie V. Davis
Viewed across Albion Basin from the Secret Lake trail, the southfacing slopes of the Flagstaff Mountain area reveal tilted Cambrian- to Pennsylvanian- age strata. The deformation of these rocks attests to the severe folding, faulting, and tilting undergone by this mountain range.
Photographer: Michael Vanden Berg
Windows form within the Tertiary-age Claron Formation as wind and water erode the brightly colored sandstone and siltstone into fins and hoodoos at Bryce Canyon National Park. Thor’s Hammer, the official icon of the Utah Geological Survey, is visible in the lower-right corner.