Full Title: Cambrian Earth systems in western Laurentia and Tonto Group of the western Grand Canyon Region
Endorsed by: GSA’s Geochronology Division
Led by: Carol Dehler, Karl Karlstrom, Stephen Rowland
Date: Wed.-Sat. 15–18 Oct. 2025
Time: 5:00 p.m. (first day); 12 p.m (last day)
Location: Las Vegas, Nevada, USA
CEUs: 2.4
Explore the iconic Cambrian Tonto Group strata in westernmost Grand Canyon and near Las Vegas to discuss results of new research and implications for long-standing questions about Cambrian Earth systems. Topics include the Sauk transgressions, the Great Unconformity, Cambrian subsidence mechanisms, a sequence stratigraphy re-interpretation of Eddie McKee’s classic Tonto Group stratigraphy, new biochronology, precise geochronology, and C-isotope chemostratigraphy. How do new datasets from the Grand Canyon inform understanding of the Cambrian Earth System and its rapid, ever-shrinking Time Scale? Cost includes transportation (mini vans), one night in Las Vegas (double occupancy) and two nights at the Dude Ranch (double occupancy) which includes meals, snacks and water, and boat usage.
This field trip will begin and end in Las Vegas, Nevada (Wed. pm and Sat. pm, respectively). Accommodation for the first night (Day 1): meet at the Best Western Inn Plus near the McCarren Airport on Wednesday night. Thursday and Friday (Days 2 and 3) will consist of two full days of field presentations and observations with overnight accommodation in shared cabins at Grand Canyon Western Ranch. The first full day (Day 2), we will slowly climb the steep Spirit Mountain (700 vertical feet), beginning at the Great Unconformity, and slowly moving through the Tapeats sheet sands, the heterolithic Bright Angel Formation, and the lower members of the Muav Formation. This is a rugged and difficult hike involving uneven ground, talus, and small cliffs. The second full day (Day 3) will be filled with shorter stops along the main road through the Cambrian section, where we will examine charismatic members of the Bright Angel Formation, intraformational unconformities, various members of the Muav Formation, and the contact with the Frenchman Mountain Dolostone. Friday afternoon will be spent at Grand Canyon West, where we will experience commanding views of the Grand Canyon stratigraphy from the Skywalk glass bridge, returning to Grand Canyon Western Ranch for the night. As we return to the Las Vegas area on Saturday morning (Day 4), there will be a morning field stop at Frenchman Mountain where we will examine key facies and surfaces in the Tonto Group and the relationship with the underlying basement. The field trip sites for Days 2 and 3 are close to Grand Canyon Western Ranch or Grand Canyon West/Skywalk, where there are restrooms, seating, food, and water available. The initial drive to Grand Canyon Western Ranch is ~2 hours from Las Vegas. Driving around the field area will involve 15 to ~1 hour in the vehicles at a time. Presentations will be given in English and the evenings will be discussion rich.
By purchasing this item, you are buying a seat on an in-person geological field trip.
Please review these Field Safety Documents. You will be contacted to provide your consent to these forms after purchasing a field trip.
Learn more about this and other GSA Connects 2025 events.
For additional information, please contact Rebecca Taormina, rtaormina@geosociety.org, GSA Field Trip and Short Program Coordinator.
Product Code: FT25CN404
Product Category: FTRIP