St. Peter’s Dome in the Jemez Mountains. Photo Courtesy PEEC
PEEC NEWS RELEASE
The Pajarito Environmental Education Center (PEEC) invites geology enthusiasts and curious explorers to join a full-day Geologic Tour to St. Peter’s Dome from 8 a.m.–5 p.m., Saturday, September 6, 2025. Led by renowned geologists, Fraser and Cathy Goff, this guided excursion into the southeastern Jemez Mountains offers a rare opportunity to discover the stunning volcanic features and geologic history of this rugged and remote region.
Participants will carpool from the Los Alamos Nature Center, departing at 8 a.m., and returning by 5 p.m. The group will explore St. Peter’s Dome, a prominent faulted block of volcanic rock uplifted 6 to 10 million years ago along the Pajarito fault zone, the western edge of the Rio Grande rift. Stops will include spectacular views, volcanic domes, obsidian-bearing debris, avalanche and lahar (mudflow) deposits, and evidence of dramatic faulting.
The tour includes two short hikes (~200 meters round-trip each) and one longer hike (~2 km round-trip) on the Boundary Peak Trail. Participants should plan to arrive at PEEC by 7:30 a.m., to check in and arrange carpooling. High-clearance, 4-wheel drive vehicles are required for the rough and poorly maintained Forest Service roads toward the end of the route. Drivers should be prepared with basic safety supplies, including tow straps, a shovel, and a small first aid kit.
This tour is designed especially for non-geologists who enjoy the outdoors and are interested in learning more about the dynamic forces that shaped the Jemez Mountains and the Pajarito Plateau.
Registration is required, and space is limited.
Admission is $55 for PEEC members and $70 for non-members.
Note: High clearance 4WD vehicles required; bring lunch, water, and hiking essentials.
For more information, visit PEEC’s website at peecnature.org/events. Stay connected on social media for updates on each week’s activities.
About the Trip Leaders:
Fraser Goff is the author of Valles Caldera: A Geologic History and the lead author of the Geologic Map of the Valles Caldera. He worked at Los Alamos National Laboratory for 26 years and has studied geothermal systems and volcanoes around the world.
Cathy Goff is an accomplished geologist and geochemist with a broad background in volcanic and geothermal research across the western U.S., Latin America, Japan, and Europe. Together, the Goffs helped produce the geologic map of Mount Taylor volcano (2019) for the New Mexico State Map Program.
About PEEC
PEEC was founded in 2000 to serve the community of Los Alamos. It offers people of all ages a way to enrich their lives by strengthening their connections to our canyons, mesas, mountains, and skies. PEEC operates the Los Alamos Nature Center at 2600 Canyon Road, holds regular programs and events, and hosts several interest groups, from birding to hiking to butterfly watching. PEEC activities are open to everyone; however, members receive exclusive benefits such as discounts on programs and gift shop merchandise. Annual memberships start at $35. To learn more, visit peecnature.org/support/membership/.