Colorado Rocks!: A Guide to Geologic Sites in the Centennial State

These 50 well-chosen sites—many on every geologist's bucket list—span Colorado's geologic history from 1.7-billion-year-old rocks of the Black Canyon to the constantly shifting landscape of the Great Sand Dunes.

The asteroid-produced iridium-enriched layer that marks the end of the dinosaurs is here, as are insects and petrified wood exquisitely preserved at Florissant Fossil Beds, the pure white marble used in the Lincoln Memorial, mysterious Unaweep Canyon that lacks a river, and colorful mounds of silicious sinter at Pagosa Springs. The Great Unconformity, a famous geologic feature tucked away in a few remote locations in other western states, pops up at seven of the featured sites. The late 1800s rush for precious metals produced a network of roads that crisscross the towering mountains, making Colorado's fascinating geology extremely accessible to the average sightseer.

With beautiful photographs and informative figures and maps, this guidebook will help you select a destination and head for the door.

Magdalena Sandoval Donahue grew up in northern New Mexico, fascinated by the mountains and valleys of the high desert at the southern end of the Rocky Mountains. She received a BS in Geological Sciences and a BS in Fine Arts from the University of Oregon, where she took structural geology from Marli Miller, her coauthor on this book. She obtained her MS and PhD from the University of New Mexico, and much of her research focused on the evolution of topography and mountain ranges in Colorado. She lives in Albuquerque with her husband, John, and three children. She is the author of Roadside Geology of Colorado, also published by GSA.

Marli B. Miller is a senior instructor and researcher at the University of Oregon. She completed her BA in geology at Colorado College in 1982 and her MS and PhD in structural geology at the University of Washington in 1987 and 1992, respectively. Marli teaches a variety of courses, including introductory geology, structural geology, field geology, and geophotography. In addition to numerous technical papers, she is the author of Oregon Rocks!, Roadside Geology of Oregon, Roadside Geology of Washington (with coauthor Darrel Cowan), all published by GSA as well as Geology of Death Valley National Park with coauthor Lauren A. Wright. Because she maintained an active interest in Colorado geology since college, she was thrilled to become a part of this project. Marli has two daughters, Lindsay and Megan.