Conference Papers
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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse almost 5,000 conference papers authored by our scientists and refine search by topic, location, year, and advanced search.
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Young (<7 Ma) gold deposits and active geothermal systems of the Great Basin: Enigmas, questions, and exploration potential
Young gold systems in the Great Basin (£ 7 Ma), though not as well studied as their older counterparts, comprise a rapidly growing and in some ways controversial group. The gold inventory for these systems has more than doubled in the last 5 years from roughly 370 tonnes (12 Moz) to 890 tonnes (29 Moz). Although these deposits are characterized by low grades, tonnages can be high and stripping rat
Authors
Mark F. Coolbaugh, Peter G. Vikre, James E. Faulds
The role of soil fertility in restoring Louisiana's coastal prairie
Studies have shown that soil nutrients, especially nitrogen (N), play an important role in the reestablishment of native prairie plant species. Soil N favors early succession species while long-lived native perennials compete favorably in N poor soils and numerous restoration studies have employed carbon additions in the form of sawdust and/or sucrose to immobilize soil nitrogen. However, this tec
Authors
Larry K. Allain
Hydrothermal alteration of the Late Eocene Caetano ash-flow caldera, north-central Nevada: A field and ASTER remote sensing study
Geologic mapping and analysis of ASTER remote sensing data were used to define the effects of a large hydrothermal system in the 12–18 by 22 km Caetano caldera. The caldera formed at ~33.8Ma during eruption of >1100km3 of the rhyolitic Caetano Tuff that left a 1 km deep basin which was partly filled by a lake. Magma resurgence resulted in shallow(<1 km) emplacement of the Redrock Canyon granite po
Authors
David John, Barnaby W. Rockwell, Christopher D. Henry, Joseph Colgan
Self calibration of small and medium format digital cameras
The knowledge of a camera’s interior orientation parameters are a prerequisite for the camera to be used in any precision photogrammetric project. Historically, the interior orientation parameters have been determined by analyzing the measured ground 3D coordinates of photo-identifiable targets, and their 2D (image) coordinates from multiple images of these targets. Camera self calibration, on the
Authors
Donald Moe, Aparajithan Sampath, Jon Christopherson, Mike Benson
Performance of map symbol and label design with format and display resolution options through scale for the national map
Symbol and label design for U.S. topographic mapping using data from The National Map has been progressing, partly in support of research by Buttenfield and Stanislawski on hydrographic generalization, and is sponsored by CEGIS, the USGS Center of Excellence for Geospatial Information Science. The work also seeks to make the best use of GIS for map design that requires no hand-work to make custom
Authors
C. A. Brewer, C. L. Hanchett, B. P. Butterfield, E. Lynn Usery
Geological sources of radionuclides and arsenic in Triassic age rift-valley sediments (Newark Supergroup) and implications for distribution in groundwater in Mercer County, New Jersey
No abstract available.
Authors
Zoltan Szabo, Julia Barringer, Steve Spayd
A Multi-Index Integrated Change detection method for updating the National Land Cover Database
Land cover change is typically captured by comparing two or more dates of imagery and associating spectral change with true thematic change. A new change detection method, Multi-Index Integrated Change (MIIC), has been developed to capture a full range of land cover disturbance patterns for updating the National Land Cover Database (NLCD). Specific indices typically specialize in identifying only
Authors
Suming Jin, Limin Yang, George Z. Xian, Patrick Danielson, Collin G. Homer
Aquifer characteristics near cuestas and their relation to rock tensile strength
Along the northeast coast of North America, extensional tectonic processes have generated lithologic and topographic features that are common to several rift basins. A cap of igneous rock overlies sedimentary rock to form a cuesta with both rock types exposed along a steep ridge flank. Field studies investigating the near‐surface hydrogeologic properties of the caprocks at several of these sites h
Authors
Roger H. Morin, William Schulz
Mechanics and modeling of flow, sediment transport and morphologic change in riverine lateral separation zones
Lateral separation zones or eddies in rivers are critically important features for sediment storage and for a variety of roles they play in riparian and aquatic ecology. As part of a larger effort to predict the morphology of lateral separation zones in the Colorado River in Grand Canyon for a selection of sediment supply and discharge scenarios, we evaluated the performance of two modeling techni
Authors
Brandy L. Logan, Jonathan M. Nelson, Richard R. McDonald, Scott Wright
Topographic evolution of sandbars: Flume experiment and computational modeling
Measurements of sandbar formation and evolution were carried out in a laboratory flume and the topographic characteristics of these barforms were compared to predictions from a computational flow and sediment transport model with bed evolution. The flume experiment produced sandbars with approximate mode 2, whereas numerical simulations produced a bed morphology better approximated as alternate ba
Authors
Paul J. Kinzel, Jonathan M. Nelson, Richard R. McDonald, Brandy L. Logan
Trait-based approaches in the analysis of stream fish communities
Species traits are used to study the functional organization of fish communities for a range of reasons, from simply reducing data dimensionality to providing mechanistic explanations for observed variation in communities. Ecological and life history traits have been used to understand the basic ecology of fishes and predict (1) species and community responses to habitat and climate alteration, an
Authors
Emmanuel Frimpong, Paul L. Angermeier