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Carving Grand Canyon’s inner gorge: A test of steady incision versus rapid knickzone migration
A recent study posits that much of the 240-m-deep inner gorge of Grand Canyon was carved between 500 and 400 ka via passage of a migrating knickzone with incision rates of ~1600 m/Ma during that time period; this was based on dating of a ca. 500 ka travertine deposit perched on the rim of the inner gorge, near Hermit Rapid, and a ca. 400 ka...
Crow, Ryan S.; Karlstrom, Karl E.; Crossey, Laura J.; Polyak, Victor; Asmerom, Yemane; McIntosh, William C. Geoelectric hazard maps for the Pacific Northwest
Maps of extreme value, horizontal component geoelectric field amplitude are constructed for the Pacific Northwest United States (and parts of neighboring Canada). Multidecade long geoelectric field time series are calculated by convolving Earth surface impedance tensors from 71 discrete magnetotelluric survey sites across the region with...
Love, Jeffrey J.; Lucas, Greg M.; Kelbert, Anna; Bedrosian, Paul A. Outburst floods provide erodability estimates consistent with long-term landscape evolution
Most current models for the landscape evolution over geological timescales are based on semi-empirical laws that consider riverbed incision proportional to rock erodability (dependent on lithology) and to the work performed by water flow (stream power). However, the erodability values obtained from these models are entangled with poorly known...
Garcia-Castellanos, Daniel; O'Connor, Jim E. Breaching of strike-slip faults and successive flooding of pull-apart basins to form the Gulf of California seaway from ca. 8–6 Ma
The geologic record of the formation of marine basins during continental rifting is uncommonly preserved. Using GIS-based paleotectonic maps, we show that marine basin formation in the Gulf of California–Salton trough oblique rift (Mexico and the United States) occurred in a stepwise manner as crustal thinning lowered elevations within the Gulf of...
Umhoefer, Paul J.; Darin, Michael H.; Bennett, Scott E. K.; Skinner, Lisa A.; Dorsey, Rebecca J.; Oskin, Michael E. Geochemical characterization and modeling of regional groundwater contributing to the Verde River, Arizona between Mormon Pocket and the USGS Clarkdale gage
We use synoptic surveys of stream discharge, stable isotopes, and dissolved noble gases to identify the source of groundwater discharge to the Verde River in central Arizona. The Verde River more than doubles in discharge in Mormon Pocket over a 1.4 km distance that includes three discrete locations of visible spring input to the river and other...
Beisner, Kimberly R.; Gardner, W. Payton; Hunt, Andrew G. Rapid 3-D analysis of rockfalls
Recent fatal and damaging rockfalls in Yosemite National Park indicate the need for rapid response data collection methods to inform public safety and assist with management response. Here we show the use of multiple-platform remote sensing methods to rapidly capture pertinent data needed to inform management and the public following a several...
Stock, Greg M.; Guerin, A.; Avdievitch, Nikita N.; Collins, Brian D.; Jaboyedoff, Michel Against the current— The Mojave River from sink to source: The 2018 Desert Symposium field trip road log
The Mojave River evolved over the past few million years by “fill and spill” from upper basins near its source in the Transverse Ranges to lower basins. Each newly “spilled into” basin in the series? sustained a long-lived lake but gradually filled with Mojave River sediment, leading to spill to a yet lower elevation? basin. The Mojave River...
Miller, David M.; Reynolds, R.E.; Groover, Krishangi D.; Buesch, David C.; Brown, H. J.; Cromwell, Geoffrey; Densmore, Jill; Garcia, A.L.; Hughson, D.; Knott, J.R.; Lovich, Jeffrey E. World distribution of uranium deposits
Deposit data derived from IAEA UDEPO (http://infcis.iaea.org/UDEPO/About.cshtml) database with assistance from P. Bruneton (France) and M. Mihalasky (U.S.A.). The map is an updated companion to "World Distribution of Uranium Deposits (UDEPO) with Uranium Deposit Classification, IAEA Tech-Doc-1629". Geology was derived from L.B. Chorlton,...
Fairclough, M. C.; Irvine, J. A.; Katona, L. F.; Simmon, W. L.; Bruneton, P.; Mihalasky, Mark J.; Cuney, M.; Aranha, M.; Pylypenko, O.; Poliakovska, K. Assessing rockfall susceptibility in steep and overhanging slopes using three-dimensional analysis of failure mechanisms
Rockfalls strongly influence the evolution of steep rocky landscapes and represent a significant hazard in mountainous areas. Defining the most probable future rockfall source areas is of primary importance for both geomorphological investigations and hazard assessment. Thus, a need exists to understand which areas of a steep cliff are more likely...
Matasci, Battista; Stock, Greg M.; Jaboyedoff, Michael; Carrea, Dario; Collins, Brian D.; Guérin, Antoine; Matasci, G.; Ravanel, L. Crustal structure and quaternary acceleration of deformation rates in central Washington revealed by stream profile inversion, potential field geophysics, and structural geology of the Yakima folds
Post‐Miocene tectonic uplift along fault‐cored anticlines within central Washington produced the Yakima Fold Province, a region of active NNE‐SSW shortening in the Cascadian backarc. The relative timing and rate of deformation along individual structures is coarsely defined yet imperative for seismic hazard assessment. In this work, we use...
Staisch, Lydia M.; Blakely, Richard J.; Kelsey, Harvey; Styron, Richard; Sherrod, Brian
Assessment of undiscovered oil and gas resources of the Susitna Basin, southern Alaska, 2017
The U.S. Geological Survey (USGS) recently completed an assessment of undiscovered, technically recoverable oil and gas resources in the Susitna Basin of southern Alaska. Using a geology-based methodology, the USGS estimates that mean undiscovered volumes of about 2 million barrels of oil and nearly 1.7 trillion cubic feet of gas may be found in...
Stanley, Richard G.; Potter, Christopher J.; Lewis, Kristen A.; Lillis, Paul G.; Shah, Anjana K.; Haeussler, Peter J.; Phillips, Jeffrey D.; Valin, Zenon C.; Schenk, Christopher J.; Klett, Timothy R.; Brownfield, Michael E.; Drake, Ronald M.; Finn, Thomas M.; Haines, Seth S.; Higley, Debra K.; Houseknecht, David W.; Le, Phuong A.; Marra, Kristen R.; Mercier, Tracey J.; Leathers-Miller, Heidi M.; Paxton, Stanley T.; Pearson, Ofori N.; Tennyson, Marilyn E.; Woodall, Cheryl A.; Zyrianova, Margarita V.
A time-lapse gravity survey of the Coso geothermal field, China Lake Naval Air Weapons Station, California
We have conducted a gravity survey of the Coso geothermal field to continue the time-lapse gravity study of the area initiated in 1991. In this report, we outline a method of processing the gravity data that minimizes the random errors and instrument bias introduced into the data by the Scintrex CG-5 relative gravimeters that were used. After...
Phelps, Geoffrey; Cronkite-Ratcliff, Collin; Blake, Kelly