Regional Field Geology Trip to eastern California

Story by Chris Van de Ven and Thom Wilch; photos by Thom Wilch

The week after graduation, geology professors Carrie Menold, Thom Wilch, and Chris Van de Ven led 15 students on the Geology 210, Regional Field Geology, trip to eastern California, primarily from Death Valley to Mono Lake. The trip started in the San Gabriel Mountains, just east of Los Angeles where we camped on the San Andreas Fault. On the way to Death Valley, we discussed playa lakes as we visited Trona and the nearby Trona Pinnacles. At the Trona Pinnacles, we examined enormous tufa towers interspersed with movie sets for “Land of the Lost.”

We camped in the Sierra Nevada at the base of Mt. Whitney (highest point on the lower 48 states) and Death Valley (at Furnace Creek, -190ft below sea level). In Death Valley, we visited Badwater (lowest elevation in North America), Ubehebe Crater, the sliding rocks of Racetrack Playa, between examining ventifacts, fault scarps, and enormous alluvial fans. We visited the bristlecone pines in the White Mountains, whose tree rings help calibrate C14 radiometric dating methods.

The trip explored Long Valley caldera and examined Bishop Tuff deposits from the enormous caldera eruption 760,000 years ago, and phreatomagmatic craters and obsidian lava domes that make up the Mono and Inyo Craters, as well as enormous moraines and active faults along the eastern Sierra Nevada range. The trip ended by viewing the tufa towers at Mono Lake and skipping rocks at Lake Tahoe.

It was a trip of extremes, from Precambrian metasediments in the White Mountains to obsidian domes only a few hundred years old along Mono Lake, from glacial moraines to volcanic craters and deposits, and from campgrounds the foot of Mt. Whitney to the bottom of Death Valley, from lush Lake Tahoe to playa lakes.

In front of rosette columnar joints (fractures) formed in the Bishop Tuff in the Owen’s River Gorge. The Bishop Tuff was erupted from the Long Valley Caldera 760,000 years ago. Ash deposits from this cataclysmic event are found throughout much of the western US -- in Texas the ash is 6 feet thick, in the Owen’s Gorge it's hundreds of feet thick. The flower pattern was created as gas escaped during cooling of massive volcanic rock. Matt Mahoney, '11, Kendall Tarrant, ’09, and Jill Fuhrman, ’09, take a break at Fossil Falls. The dry falls and potholes cut into basalt lava flows were formed by catastrophic flooding at the end of the last ice age. The water source is thought to be Owens Lake.   Will Ward, ’11, with bear sign at Whitney Portal campground in the eastern Sierra Nevadas.

Menold on the bizarre boulder “racetracks” in Death Valley National Park. The tracks are formed by high wind forces pushing boulders across the dry lake bed. “I originally was going to be an earth science major for secondary education," says Melissa Light, '10 (standing behind table), explaining that the California trip inspired her to change to a geology major. "Visiting the geology that we studied in class was really exciting and enjoyable. A personal highlight for me was Death Valley. Although it was hot... really really hot... it had some of the most gorgeous places that I have ever seen. It was also really helpful to have all of the professors there explaining things as we went along."

The group photo at Badwater, Death Valley National Park.  With a lapse rate of 5.5*/1000 feet it was a brutally hot 105*F in the shade at -282 feet below sea level.