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2014 Spring Break field trip: Kettleman Hills and Death Valley area, page 1
In January of this year, Assistant Professor of Integrative Biology and UCMP Curator Seth Finnegan sent an e-mail out to the museum community to gauge the interest in a Spring Break field trip. His idea was to spend a day looking at Cenozoic sections in the Central Valley, such as the Pliocene outcrops in the Kettleman Hills near Coalinga, and then to move on to the Death Valley area, where we'd spend a few days examining some classic Paleozoic marine sequences. Seth said "My intent is to provide graduate students who may not have spent much time in the field an opportunity to see fossils in their stratigraphic context, to learn some of the basics of using sedimentology and taphonomy to make paleoecological inferences, and to consider the ways in which paleontological information is filtered through the geological record."
Enough people were interested to make such a trip worthwhile, so the logistics were worked out, two four-wheel-drive vehicles were reserved, permission to visit the Kettleman Hills localities was obtained, and lodgings were arranged for in Shoshone, just south of Death Valley (for two nights; we would be camping the rest of the time).
On Sunday, March 23, all interested parties gathered at the North Berkeley BART parking lot. Some people planned to go only as far as the Kettleman Hills and would be returning to Berkeley late Monday. This group included UCMP Director Charles Marshall, his wife Swee Peck Quek and their daughter Kiri, Assistant Director for Education and Public Programs Lisa White, Senior Museum Scientist Pat Holroyd, and grad student Liz Ferrer. Those joining Seth for the whole week would be UCMP graphic designer Dave Smith and grad students Junying Lim, Winnie Hsiung, Camilla Souto, Lucy Chang, Ashley Poust, and Renske Kirchholtes; these eight went in the two rented GMC Yukons, while Charles and Lisa drove their own cars.
After a two-hour-and-45-minute drive, we reached Coalinga, then, heading west, we followed Lisa to exposures of the late Miocene Santa Margarita Formation along Los Gatos Creek Road. These are primarily light-colored sandstones with some conglomerates and occasional large boulders, all deposited when the area was a shallow shelf setting. Continuing west, Lisa pointed out some nicely bedded turbidites deep ocean, high-density sediment flow deposits from the Cretaceous Moreno Formation of the Great Valley Sequence before pulling into the somewhat remote Los Gatos Creek County Park. Serenaded by howling coyotes and hooting owls, we spent a pleasant night of camping here.
On Monday, with Lisa leading the way, we headed south of Coalinga and entered the Kettleman Hills, driving along poorly maintained oil company roads to a series of San Francisco State University localities that Lisa had frequented during her tenure there. The Kettleman Hils are a series of elongated domes or plunging anticlines and the first stop was at a thick exposure of the early Pliocene Patinopecten Zone (named for a species of scallop found in these rocks) within the Etchegoin Formation. The zone's brown sandstones are full of the sand dollar Dendraster and bivalves preserved in life position. Above the Patinopecten Zone is the younger, browner, lichen-covered Macoma Zone (Macoma is a large marine clam). These rocks and their fossils tell us that this was a shallow marine to estuarine setting during the early Pliocene.
We continued on to a good exposure of the middle Pliocene Siphonalia Zone (Siphonalia is a marine gastropod), stratigraphically just above the Macoma Zone. The rocks here are composed of brown silts and bluish sandstones. Then, leaving the oilfield, it was out to Skyline Boulevard and northeast towards route 5. We parked on the shoulder, climbed through a barbed wire fence, and hiked to the easternmost ridge of the Kettlemans, on the eastern limb of the North Dome Anticline. In the rocks we traversed here from the upper Pliocene Acila Zone (Acila is a small marine clam) of the San Joaquin Formation to the Pleistocene Amnicola Zone (Amnicola is a freshwater gastropod) of the Tulare Formation the demise of the marine basin was chronicled, with oyster beds indicating the transition from a saltwater to freshwater environment. In an upper section, a gypsum evaporite layer signaled the advent of terrestrial deposition.
At this point, Charles and his family and Lisa with Pat and Liz headed back to Berkeley, while the rest of us continued on to Bakersfield and Tehachapi, arriving at Red Rock Canyon State Park after sunset. We did not explore the park, but appreciated its badlands composed of Miocene mudstones and sandstones of terrestrial origin.
Tuesday morning's first stop was Fossil Falls Scenic Area, north of Little Lake. The falls, now dry and cutting through lava beds, mark the course of the vanished Owens River. Then it was up 395 and east on 190 towards Death Valley National Park. We stopped at the Father Crowley Vista to take in the amazing view of the Panamint Valley to the east. Across the valley was the Panamint Range, with its light-colored Paleozoic carbonates beneath darker Cenozoic lava flows. We were now in the Basin and Range Province where crustal stretching has resulted in valleys like Panamint and Death Valleys formed from downthrown blocks of land. Continuing on into the park, we set up camp at the Stovepipe Wells campground. Although it was still early in the day, we all pitched our tents in order to "claim our turf."
Back in the two Yukons, we drove out Daylight Pass Road to where the one-way Titus Canyon Road begins. After a quick stop at the short-lived ghost town of Leadfield (it survived for less than a year), we drove deeper into the canyon and stopped to look at exposures of the Bonanza King Formation. These thick Middle to Late Cambrian rocks are composed primarily of dolomite and dolomitic limestones, some with alternating light and dark layers of equal thickness. Seth pointed out that such layers have been shown in some cases to correlate with Milankovich climate cycles driven by cyclic changes in the Earth's orbital parameters. Within the Bonanza King we found trilobite hash and ripple marks, evidence of its marine origins.
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