Fall colors and snow compliment brightly colored lichen on Miocene-age volcanic boulders on the shore of Johnson Valley Reservoir. Cloud shadows dapple the Fish Lake Hightop, one of several high plateaus in central Utah dominated by Tertiary-age volcanic rocks.
Fishlake National Forest, Sevier County, Utah. Photo by J. Lucy Jordan.
Near the base of Notch Peak, pink Jurassic-age granite intrudes much older thinly bedded gray argillite and white marble of the Cambrian-age Marjum Formation. Deep in the Earth’s crust 170 million years ago, high heat and fluids from the granite metamorphosed the surrounding rock, turning limestone into marble and shale into argillite.
House Range, Millard County, Utah. Photo by Mark Milligan.