2017 Friends of the Pleistocene Guidebook Northern Owens Valley 7 – 9 October 2017 Trip Leaders Fred M. Phillips, Drew Levy, Paul Hancock Dedicated to the memories of Alfred Knopf, Elliot Blackwelder, Paul Bateman, and Clem Nelson “we stand on the shoulders of giants…” 2 Table of Contents Logistics 4 Day 1 5 Road Log: Cedar Flat to Waucoba embayment 5 Stop 1.1 The Waucoba embayment 9 Waucoba Lake beds by De Masi et al. 9 Waucoba faulting by Phillips and Kirby 16 Road Log: Waucoba embayment to Chalfant Valley 23 Stop 1.2 Chalfant Valley 27 Bishop tuff at Chalfant Valley by Hildreth and Fierstein 27 Reactivated Laramide shear by Bartley et al. 31 Alluvium of Black Canyon by Phillips and Jayko 40 Slip partitioning on the WMFZ by Phillips 47 Tectonic geomorphology of the White Mountains by Katona and Knott 55 Road Log: Chalfant Valley to Fish Slough 62 Stop 1.3 Fish Slough History of aquatic species by Sada and Bacon 63 Tectonic significance of Fish Lake fault by Phillips 71 Road Log: Fish Slough to Round Valley 73 Stop 1.4 Round Valley 74 Tectonics of the Sierra Nevada frontal fault zone by Levy 75 Tectonic warping of surfaces in the Owens Valley by Pinter The Round Valley fault by Phillips 87 Day 2 94 Road Log: Cedar Flat to Bishop Creek 94 Stop 2.1 Bishop Creek 97 Glaciation of Bishop Creek by Phillips 97 Road Log: Bishop Creek to Owens River Gorge 108 Stop 2.2 Owens River Gorge 109 (Re)incision of Owens River Gorge by Hildreth 110 Road Log: Owens River Gorge to Long Valley 116 Stop 2.3 Long Valley 116 Pleistocene Long Valley Lake by Hildreth 117 Road Log: Long Valley to Convict Lake 122 Stop 2.4 Convict Creek 123 Cosmogenic glacial chronology for Convict Lake by Putnam and Hatchett 124 Day 3 133 3 Road Log: Cedar Flat to Warren Bench 133 Stop 3.1 Warren Bench 134 Faulting of the Coyote Warp by Phillips 135 Road Log: Warren Bench to Crater Mountain 141 Stop 3.2 Crater Mountain 141 Holocene slip on the Owens Valley fault by Haddon et al. 142 Long-term slip on the OVF by Kirby and Phillips 150 Road Log: Crater Mountain to Poverty Hills 154 Stop 3.3 Poverty Hills 154 Quantifying distributed extension across the Owens Valley by Kirby and Phillips 154 References for Road Log 162 Description and Logistics Locality: The Owens Valley is a deep trough between the Sierra Nevada on the west and the White/Inyo Mountains on the east. The valley is tectonically very active, with most of the dislocation being accommodated on transtensional systems of faults. The climate fluctuations of the Pleistocene left a major imprint on the area, including impressive moraines at canyon mouths and evidence of extensive pluvial lakes. Scope: The 2017 trip will examine mountain-front faulting along both the White Mountains and Sierra Nevada and the valley-center Owens Valley fault. We will visit early Pleistocene lacustrine exposures in the Waucoba embayment, see new evidence for mid-to-late Pleistocene lakes in Long Valley, and inspect dated moraines at Bishop Creek and in Long Valley. The area is the source of the widely distributed Bishop Tuff and we will visit the source area in Long Valley and extensive exposures of the ignimbrite sheet, as well as other minor volcanic centers. The last time there was a Pacific Cell FOP in the northern Owens Valley was in 1971! The headquarters for the 2017 Pacific FOP will be the USFS Cedar Flat campground The campground has pit toilets (which we will supplement with porta- potties), but no running water. It is 12 miles east of the small town of Big Pine down a winding mountain road, so come prepared with water, ice and all necessary supplies. It is at 2250 m (7400 feet), so expect nights to be cool, possibly below freezing. Hopefully we will have glorious fall weather for the field trips, but if a cold front comes through it is not impossible we could be snowed on, and if there is a heat wave it could be up in the 90’s. In other words, be prepared for anything. Vehicles: The routes for Days 1 and 2 should be passable for passenger cars with reasonable clearance (not low-slung sports cars!). That for Day 3 will involve dirt roads with some projecting boulders and several ~2 foot-deep stream crossings, so high clearance vehicles are required. Plan on car pooling on Day 3 with somebody who has a high-clearance vehicle if you do not! In general, parking a large number of vehicles and walking back and forth from them to the actual stop sites are the number-one waste of time on FOP trips, so please make every attempt to car pool if you are in a vehicle that has only one or two people in it. Directions: The 2017 Pacific Cell FoP will be headquartered at the USFS Cedar Flat Group Campsite in Inyo National Forest. To reach Cedar Flat, drive either north or south 4 on U.S. 395 to reach Big Pine, in the northern Owens Valley. Drive to the north end of Big Pine. Turn right on California State Highway 168. This intersection is easy to spot because it is marked by both a Giant Sequoia tree and a giant American flag. Drive 12.5 miles east on 168 (in 2.2 miles you reach the intersection with the Death Valley/Saline Valley Road; continue straight on 168, do not turn off toward Death Valley). The road proceeds up a narrow and twisty canyon before emerging onto the broad expanse of Cedar Flat. In 12.5 miles from the US 395 intersection you will see the sign for the Cedar Flat Group Camp with the turnoff on the north side of 168. The coordinates of this intersection are 37.27674 N and -118.1512 E. Driving ~0.3 mile north on a gravel road you encounter three group camp sites: Camp Nelson, Camp Noren, and Camp Ferguson. All three sites have been reserved for the FOP. When you arrive, please check in at the FOP headquarters to receive your guidebook and T-shirt. Note that the Cedar Flat facility does not have running water. Vault toilets and port-a- potties will be provided. The nearest point for resupply is Big Pine, 12 miles to the west. Make sure you have adequate water, food, gasoline, and other supplies for the trip before you leave Big Pine. You are completely responsible for your own provisions while on the trip. Regulations and Safety Inyo National Forest is currently under fire restrictions, so no open fires except in specifically constructed structures at the Cedar Flat Group Camps. We do not have any permits for digging or sample collection, so do not excavate anything (except maybe a poop hole) and do not collect rocks, soil, etc. Bring at least a gallon of water per person per day (remember that no water is provided at Cedar Flat CG). Never drive off the recognized road or across vegetation. We will have to turn across traffic, or into high-speed traffic, numerous times on this trip. Other drivers are not expecting a slow-moving caravan. EXERCISE EXTREME AWARENESS AND CAUTION WHEN GETTING ONTO OR OFF OF HIGH-SPEED HIGHWAYS. On the daily trips don’t drive by yourself. Carpool with somebody else to avoid slow stops, congestion, and pollution. Day 3 will require high-clearance vehicles. Road Log Day 1 Cedar Flat to Horton Creek: Sedimentary Records of Climate and Tectonics from 3 to 0.5 Ma, and Active Faulting, in the Northern Owens Valley The field trip will depart from Cedar Flat Group Camp at 8:00 AM, Saturday, October 7. 5 Summary: The northern Owens Valley is a region of dramatic topography and active volcanism. These characteristics stem from its role as a locus of transtensional strain associated with the transform plate boundary on the west coast of North America. Approximately two-thirds of the total strain between the stable North American craton and the east side of the San Andreas Fault is accomplished in the 100 km between Piper Peak, on the east side of Fish Lake Valley, and Wheeler Crest, on the west side of Owens Valley. Unfortunately, neither the history of strain accumulation nor the mechanisms by which faults accommodate the strain are currently very well understood. On the first day of the 2017 Friends of the Pleistocene Field Trip we will examine sedimentary deposits (lacustrine, fluvial, and alluvial fan) in the Waucoba embayment and along the front of the White Mountains between Black Canyon and Piute Canyon that contain a record of the opening of the Owens Valley during the Plio-Pleistocene. We will also see fault scarps and faulted mountain fronts that contain clues to the geometry and kinematics of the faults that are largely responsible for the accumulation of tectonic strain across the region. Prior to ~12 Ma the region was apparently a low-relief upland of moderate elevation (perhaps ~2.5 km) that stretched from the central Sierra Nevada to central Nevada (Phillips, 2008; Jayko, 2009; Henry et al., 2012). Both thermochronology (Stockli et al., 2003; Lee et al., 2009) and 40Ar/39Ar dating of regional-scale volcanic eruptions (Phillips et al., 2011) indicate that the Owens Valley area was extended during two pulses that began at 11.8 and 3.4 Ma. During the Miocene pulse the extension was oriented east-west, whereas by the time of the Pliocene pulse the extension vector had shifted to northwest-southeast (Jones et al., 2004; McQuarrie and Wernicke, 2005).