ON THE ROCKS Presents

Geologic Wonders of Ouray: Exploring the "Switzerland of America"

September 19-21, 2025

Trip Leader: David Gonzales & Steve Cumella

Trip Coordinator: Rob Diedrich

This fall, RMAG heads back to the San Juans for an exciting two-day field trip exploring the remarkable geology of Ouray, Colorado—fondly known as the "Switzerland of America." Leading the tour are RMAG members David Gonzales, geology professor at Fort Lewis College, and Steve Cumella, a local geologist from Ouray. Attendees will examine the region’s fascinating geologic history, covering everything from Paleozoic to Cenozoic stratigraphy, Laramide to Oligocene volcanism, striking unconformities, and Pleistocene glaciation to its famous hot springs—all set against the stunning backdrop of late September’s vibrant fall foliage. Secure your spot soon—this trip is sure to fill up fast!

Trip Description

David Gonzales, professor of geology at Fort Lewis College, and Steve Cumella, a local Ouray geologist, will lead a fieldtrip to look at Ouray’s spectacular geology. Sometimes called the “Switzerland of America” the town was named for Chief Ouray, who was leader of the Ute Tribe around 1875.

A geologic history that spans 1,700 million years is exposed in the vicinity of Ouray. This chronicle presents an extensive record of events that includes uplift during the Ancestry Rocky Mountains and Laramide orogenies. Paleozoic to Cenozoic sedimentary and volcanic rocks are intruded by 65-20 Ma plutonic rocks that influenced mineralization in the area. Laramide intrusions form some impressive geologic features like the Blowout stock north of town and sheer 300-foot-thick granodiorite cliffs under the Twin Peaks west of town. Numerous granodiorite dikes and sills can be seen intruding the Paleozoic and Mesozoic rocks surrounding Ouray.

Major unconformities in the record are one of the signature features in this area, revealing significant periods of uplift related to tectonics and magmatism. Uplift in the past 35 Ma coupled with Pleistocene glaciation resulted in erosion of the deep valleys throughout the San Juan Mountains. Ouray resides in one of these valleys.

Tilting of the Paleozoic rocks during the Ancestral Rockies uplift resulted in the impressive unconformity exposed in the cliffs on the northeast side of Ouray. Another impressive unconformity can be seen in the Amphitheater east of Ouray, where a paleovalley greater than 1,000 ft deep was filled with onlapping layers of volcaniclastics of the Oligocene San Juan Formation. The greatest unconformity, at least in terms of the time span, is exposed above the Box Canyon Falls on the southwest side of Ouray. Here 1.7 Ga near-vertical quartzite beds of the Uncompahgre Formation are overlain by the gently dipping Devonian Elbert Fm.

The Ouray Hot Springs is fed by geothermal waters that moved up along the Ouray fault on the south side of town. This Ancestral Rockies-aged fault juxtaposes the 1.7 Ga Uncompahgre Formation against the Mississippian Leadville Limestone.

These and other geologic wonders will be observed during this two-day fieldtrip.

Logistics

The fieldtrip will start and finish each day at the Ouray Hot Springs parking lot and will visit various sites in and near the town of Ouray. Some of the stops will involve up to one-mile hikes on trails (some that are rocky) that gain over 400 ft in elevation, so participants should be in good physical condition and must wear sturdy hiking boots. Elevations range from 7,500 to 8,800 ft, so bring a hat, sunscreen, and a jacket in case of cool weather. Participants are encouraged to carpool during the field trip to minimize the number of vehicles; parking is very limited at some of the stops. PLEASE BRING YOUR OWN FOOD OR BEVERAGES, BECAUSE THEY WILL NOT BE PROVIDED.

Lodging 

A hotel block has been arranged at the Twin Peaks Lodge, registrants will recieve the booking links as part of their registration. Because it is peak season the rooms will be released after August 5th. 

The rate includes breakfast. 

Cost

• $125 for members
• $175 for non-members. (not a member? click here to join)
• Are you a student? email staff@rmag.org

Registration Closes September 8, 2025. 

Refunds for the September 19-21, trip are only available until September 1, 2025

If you are unable to attend, your registration for all RMAG events are transferable. RMAG members may transfer their registration to another RMAG member, and non-members can transfer their registrations to whomever they wish. Should an RMAG member wish to transfer their registration to a non-member, the non-member would need to pay the balance between the member and non-member price.

Waivers

All registrants must fill out the Waiver and Release of Liability and Medical Emergency Form. Those who fail to complete these form will not be permitted to attend the field trip.