Editors: J. Michael Timmons and Karl E. Karlstrom
Carved in the last 6 million years by the Colorado River and its tributaries, Grand Canyon is one of the premier geologic landscapes in the world. Three series of rocks are visible in the canyon walls. (1) The horizontal sedimentary rock layers that make up the upper strata throughout the Canyon are Paleozoic in age, deposited between ca. 525•270 Ma, and represent multiple episodes of marine incursion and retreat from the continental interior. (2) The tilted rock layers, well preserved in fault blocks of eastern Grand Canyon, are Mesoproterozoic rocks of the 1.2 to 0.75 Ga Grand Canyon Supergroup that reveal discrete episodes of sedimentation and tectonism. (3) In the depths of Grand Canyon, the oldest rocks are the igneous and metamorphic rocks known as Vishnu basement rocks that record the formation and modification of the region’s continental crust from 1840 to 1660 Ma. Illustrated with numerous color photographs and accompanied by the most detailed geologic map of eastern Grand Canyon to date, this volume provides an easy-to-understand summary of the geologic stories encoded by rocks and landscapes of Grand Canyon.