Field Camp ‘26, one week in!

SEOE Geology Field Campers map intrusive relationships in the Benton Range, California.

Wednesday, May 20, 2026, North Roberts Mountain, Nevada

All is well at the USC School of the Earth, Ocean and Environment Geology Field Camp. In stark contrast to our start last year in which flight delays had us up for more than 24 hours as we rerouted through Denver, this year was smooth sailing to Sacramento. There, we picked up our SUVs and joined our gear van, The Badger, at Spanish Flat campground on Lake Berryessa in the California Coast Ranges between Winters and Napa, where JD Ross and Chase Robinson had done a splendid job setting up camp, having arrived a few days prior after a 3000 mile journey across the country with the vast majority of our gear and luggage. After setting up personal tents, taking a few dips and casts in the lake, we settled down for a supper of camp shakshuka (cooked on a griddle instead of in an oven) and an early bedtime, ready to start field camp proper.

Griddle Shakshuka — supper one of Field Camp ‘26.

The following day gifted us perfect weather as we visited classic localities of the Franciscan complex that recorded the subduction of Pacific realm oceanic lithosphere beneath North America starting in the late Jurassic. In contrast to last year when the tide tables required a visit to Rodeo Cove first thing, this year we began at Ring Mountain on the Tiburon Peninsula, where we examined blocks of blueschist, eclogite, greenschist and peridotite that outcrop amongst a sea of serpentinite. We proceeded on to Rodeo Cove to examine bedded chert and litharenites before ending the field day examining pillow basalts scraped from the ocean floor at Point Bonita in the Marin Headlands, with lovely views of the Golden Gate Bridge, San Francisco, as well as marine and avian wildlife of the most biogeographically unique part of our transect of the North American Cordillera that we will pursue over the next month.

Field campers examine deformed blueschist of the Franciscan melange at the classic Turtle Rock locality on Ring Mountain, Tiburon Peninsula, California.

Friday May 15 gave us similarly excellent weather as we examined sedimentary rocks of the Jurassic and Cretaceous Great Valley Group at the mouth of Lake Berryessa and along Cache Creek on the eastern edge of the Coast Ranges in the northern Sacramento Valley. Homoclinally dipping tabular beds provided great opportunities for students to practice their attitude measurements using pocket transits, as they compiled lithologic data for the second of three geologic units the students describe in their subduction triad assignment. Returning to camp after a grocery re-supply in Winters, we began breaking down camp in anticipation of a long drive the following day across the Great Valley, up the western slope of the Sierra Nevada and then down its east side to the Benton Ranges.

Students complete a unit description of the Jurassic-Cretaceous Great Valley Group along Cache Creek in the eastern Coast Ranges of California.

Our journey to the Benton Range went flawlessly, with stops to examine auriferous (gold-bearing) Eocene braided stream deposits on the western slope en route to Donner Pass at the crest of the northern Sierra Nevada. The weather at Donner Pass was spectacular — warm, clear and no breeze, giving us plenty of time to examine and discuss the enclave-bearing tonalites of the Lake Mary pluton — one of hundreds of felsic intrusive rocks that compose the Sierra Nevada batholith. Last year we were rushed off the outcrop after less than 15 minutes by a wintry mix of snow, hail and rain, so it was especially nice to have a time for an extended discussion of how subduction zones work, and what the geology we have studied captures (and doesn’t capture) those processes. Following a stop to see Miocene tuffs in depositional contact with mid-Cretaceous batholithic plutons at Donner Summit, we descended town to Truckee and Lake Tahoe and made our way along the range front of the eastern Sierra — with a short stop at Mono Lake — to the Benton Range where we set up camp and enjoyed a quick meal of tomato penne with baguette before retiring for the night at our first of many wild camps.

Field campers examine enclaves captured within the Lake Mary tonalite at McGlashan Point on Donner Pass, California.

Sunday May 17 started beautifully in the Benton Range, with backlit views of the White Mountains to the east, and the sun-bathed snowy High Sierra to the west. Students began their first map project, reconstructing the order of intrusive events through crosscutting map relationships between hornfels-grade metasedimentary rocks, pegmatitic granodiorite, and porphyritic, mafic and silicic dikes. By mid-day the wind had picked up, keeping temperatures cool, albeit adding a bit of stress as students learned to navigate mapping in windy conditions. Around mid-afternoon, a significant haboob approached from the northeast, obscuring view of the 12,000’+ White Mountains just a few kilometers away, and converging with winds howling down from the eastern Sierra. As the wind continued to pick up, those passing through camp reported over our radios that tents were beginning to move, and gear was taking flight. We retreated, while those in camp did what they could to batten down the hatches and secure personal tents. As winds continued to increase to something in the 60-70 knot range, we scrambled to weigh down tent stakes with rocks and tent interiors with humans and luggage. Nonetheless, three tents collapsed with exploded rain-flys, and others suffered minor tears. With winds projected to continue into the early hours of the morning, for only the second time in field camp history, we made the decision to abandon camp, packing up in pursuit of the solace of the Motel 6 in Bishop, where we were lucky to book rooms despite the start of Bishop’s Mule Days festival the following day. Battered and exhausted we enjoyed meals cooked not by us, and hot showers, and sleep with a roof over our heads.

The Great Benton Haboob of ‘26 left its mark on the gear and souls of SEOE Geology Field Camp.

After a visit to the Chalfant quarry to examine the Bishop Tuff on Monday morning, students enjoyed a partial day-off in Bishop where they caught up on laundry and visited bookstores, and the staff re-supplied for our upcoming transect of Nevada. We left Bishop in the mid-afternoon for a brief stopover camp along Peavine Creek canyon in the Toiyabe Range north of Tonopah, en route to our next more permanent camp in the North Roberts Mountains in central Nevada. With a restful — low-wind! — camp along the creek, our field confidence and joy for the wilderness returned quickly. Today we made our way to Camp Four near the mouth of Kelley Creek Canyon in the North Roberts Mountains, west of Alpha, stopping briefly at the Bartine Hot Springs for a conversation about hydrothermal circulation and tectonic settings, and of course a quick restorative soak. Onward.

A brief respite — and discussion of hydrothermal magmatic systems — at Bartine hot springs en route to Camp Four in central Nevada.