Montana Rocks: A Guide to Geologic Sites Under the Big Sky

Every vista in Montana tells a geologic story, and in Montana Rocks! author Rob Thomas selects sixty of the very best geologic sites to reveal how the Big Sky state's landscapes were built, reshaped, and transformed over time.

Each carefully chosen stop is a geologic time capsule, brought to life with beautiful photographs and clear, indispensable maps that shed light on crucial details. The sites are organized chronologically, inviting armchair readers and travelers alike to journey through the state's geologic history from some of the world's oldest rocks on the Beartooth Plateau to recent rockfalls in the state's biggest city, Billings.

Sandwiched between the oldest and youngest sites are tales of ancient mountain building, fossil-rich limestone deposited in tropical seas, and torrential floods that drained ice age lakes. Glacier National Park, Montana's crown jewel, boasts four highlighted sites, while others explore volcanic ash deposits carried north from Yellowstone's colossal eruptions.

With this book in hand, readers will visit a nesting ground of dinosaurs, an earthquake-triggered landslide, crystal-bearing weathered granite, and thrust faults that carried entire mountains over younger rocks, bringing Montana's long and complex geologic history into focus.

Author: Robert C. Thomas
Publisher: Geological Society of America
Published: 06/06/2026
Pages: 160
Binding Type: Paperback
Weight: 0.95lbs
Size: 8.30h x 8.90w x 0.40d
ISBN: 9780813741277

About the Author
Thomas, Robert C.: - Rob Thomas is a professor of geology in the heart of Yellowstone Country at The University of Montana Western in Dillon, Montana. He has co-led numerous GeoVentures fieldtrips in Yellowstone for the Geological Society of America; spent over twenty-five years teaching geology field courses and camps, including many years with the Yellowstone-Bighorn Research Association geology field camp; and produced numerous publications, geological road signs, and public presentations about Yellowstone Country. He has received numerous awards and honors, including the prestigious U.S. Outstanding Baccalaureate College Professor of the Year Award from The Carnegie Foundation for the Advancement of Teaching and the Council for Advancement and Support of Education.Feeney, Chelsea M.: - Chelsea M. Feeney was raised at the foothills of the Blue Ridge Mountains in central Virginia and received a BS in geosciences from Virginia Tech. Her geologic pursuits led her to the Northwest where she earned her MS in geology from the University of Montana and published her first map through the Montana Bureau of Mines and Geology. She has been producing geologic maps and figures for Mountain Press Publishing Company since 2009 and owns her own custom cartography business (www.cmcfeeney.com). Chelsea lives in Moscow, Idaho, with her husband Dennis, a fellow geologist, and their two children.