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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 more than 82,000 reports authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Occurrence model for magmatic sulfide-rich nickel-copper-(platinum-group element) deposits related to mafic and ultramafic dike-sill complexes Occurrence model for magmatic sulfide-rich nickel-copper-(platinum-group element) deposits related to mafic and ultramafic dike-sill complexes
Magmatic sulfide deposits containing nickel (Ni) and copper (Cu), with or without (±) platinum-group elements (PGE), account for approximately 60 percent of the world’s nickel production. Most of the remainder of the Ni production is derived from lateritic deposits, which form by weathering of ultramafic rocks in humid tropical conditions. Magmatic Ni-Cu±PGE sulfide deposits are...
Authors
Klaus J. Schulz, Laurel G. Woodruff, Suzanne W. Nicholson, Robert R. Seal, Nadine M. Piatak, Val W. Chandler, John L. Mars
Occurrence of pesticides in groundwater and sediments and mineralogy of sediments and grain coatings underlying the Rutgers Agricultural Research and Extension Center, Upper Deerfield, New Jersey, 2007 Occurrence of pesticides in groundwater and sediments and mineralogy of sediments and grain coatings underlying the Rutgers Agricultural Research and Extension Center, Upper Deerfield, New Jersey, 2007
Water and sediment samples were collected from June through October 2007 from seven plots at the Rutgers Agricultural Research and Extension Center in Upper Deerfield, New Jersey, and analyzed for a suite of pesticides (including fungicides) and other physical and chemical parameters (including sediment mineralogy) by the U.S. Geological Survey. Plots were selected for inclusion in this...
Authors
Timothy J. Reilly, Kelly L. Smalling, Michael T. Meyer, Mark W. Sandstrom, Michelle Hladik, Adam R. Boehlke, Neil S. Fishman, William A. Battaglin, Kathryn Kuivila
Offshore pelagic fish community Offshore pelagic fish community
Lake Ontario’s offshore zone, as defined by Stewart et al. (2013), comprises all waters of the lake where the bottom depth is greater than 15 m excluding those in embayments. When the lake is thermally stratified during June-October, the offshore pelagic zone includes the upper-warm and middle-cool layers of water which serve as important habitat for Alewife and other prey fishes, and...
Authors
Michael Connerton, Jana Lantry, Maureen Walsh, M. E. Daniels, James Hoyle, James Bowlby, James H. Johnson, Daniel Bishop, Ted Schaner
One hundred volatile years of volcanic gas studies at the Hawaiian Volcano Observatory One hundred volatile years of volcanic gas studies at the Hawaiian Volcano Observatory
The first volcanic gas studies in Hawai‘i, beginning in 1912, established that volatile emissions from Kīlauea Volcano contained mostly water vapor, in addition to carbon dioxide and sulfur dioxide. This straightforward discovery overturned a popular volatile theory of the day and, in the same action, helped affirm Thomas A. Jaggar, Jr.’s, vision of the Hawaiian Volcano Observatory (HVO)...
Authors
A.J. Sutton, Tamar Elias
One-Water Hydrologic Flow Model (MODFLOW-OWHM) One-Water Hydrologic Flow Model (MODFLOW-OWHM)
The One-Water Hydrologic Flow Model (MF-OWHM) is a MODFLOW-based integrated hydrologic flow model (IHM) that is the most complete version, to date, of the MODFLOW family of hydrologic simulators needed for the analysis of a broad range of conjunctive-use issues. Conjunctive use is the combined use of groundwater and surface water. MF-OWHM allows the simulation, analysis, and management...
Authors
Randall T. Hanson, Scott Boyce, Wolfgang Schmid, Joseph D. Hughes, Steffen W. Mehl, Stanley A. Leake, Thomas Maddock, Richard G. Niswonger
Origins and delineation of saltwater intrusion in the Biscayne aquifer and changes in the distribution of saltwater in Miami-Dade County, Florida Origins and delineation of saltwater intrusion in the Biscayne aquifer and changes in the distribution of saltwater in Miami-Dade County, Florida
Intrusion of saltwater into parts of the shallow karst Biscayne aquifer is a major concern for the 2.5 million residents of Miami-Dade County that rely on this aquifer as their primary drinking water supply. Saltwater intrusion of this aquifer began when the Everglades were drained to provide dry land for urban development and agriculture. The reduction in water levels caused by this...
Authors
Scott T. Prinos, Michael A. Wacker, Kevin J. Cunningham, David V. Fitterman
Overview of the potential and identified petroleum source rocks of the Appalachian basin, eastern United States Overview of the potential and identified petroleum source rocks of the Appalachian basin, eastern United States
The Appalachian basin is the oldest and longest producing commercially viable petroleum-producing basin in the United States. Source rocks for reservoirs within the basin are located throughout the entire stratigraphic succession and extend geographically over much of the foreland basin and fold-and-thrust belt that make up the Appalachian basin. Major source rock intervals occur in...
Authors
James L. Coleman, Robert T. Ryder, Robert C. Milici, Stephen Brown
Pacific Continental Shelf Environmental Assessment (PaCSEA): aerial seabird and marine mammal surveys off northern California, Oregon, and Washington, 2011-2012 Pacific Continental Shelf Environmental Assessment (PaCSEA): aerial seabird and marine mammal surveys off northern California, Oregon, and Washington, 2011-2012
Marine birds and mammals comprise an important community of meso- and upper-trophic-level predators within the northern California Current System (NCCS). The NCCS is located within one of the world’s four major eastern boundary currents and is characterized by an abundant and diverse marine ecosystem fuelled seasonally by wind-driven upwelling which supplies nutrient-rich water to...
Authors
Josh Adams, Jonathan J. Felis, John W. Mason, John Y. Takekawa
Palila abundance estimates and trends Palila abundance estimates and trends
The palila (Loxioides bailleui) population was surveyed annually during 1998−2014 on Mauna Kea Volcano to determine abundance, population trend, and spatial distribution. In the latest surveys, the 2013 population was estimated at 1,492−2,132 birds (point estimate: 1,799) and the 2014 population was estimated at 1,697−2,508 (point estimate: 2,070). Similar numbers of palila were detected...
Authors
Paul C. Banko, Kevin W. Brink, Richard Camp
Palila restoration research, 1996−2012 Palila restoration research, 1996−2012
The Palila Restoration Project was initiated in 1996 by the U.S. Geological Survey to assist government agencies mitigate the effects of realigning Saddle Road (Highway 200) through Palila Critical Habitat (U.S. Fish and Wildlife Service 1998, Federal Highway Administration 1999). Ecological research on the palila (Loxioides bailleui), an endangered Hawaiian forest bird, carried out by...
Authors
Paul C. Banko, Chris Farmer, Carter T. Atkinson, Kevin W. Brinck, Richad Camp, Colleen Cole, Raymond Canner, Steve Dougill, Daniel Goltz, Elizabeth Gray, Steven C. Hess, Jennifer Higashino, Susan I. Jarvi, Luanne Johnson, Leona Laniawe, Megan Laut, Linda Miller, Christopher J. Murray, Daniel Nelson, David L. Leonard, Peter Oboyshi, Leanne Patch-Highfill, David D. Pollock, Kalei Rapozo, Marla Schwarzfeld, John Slotterback, Robert M. Stephens
Palila Restoration Research, 1996−2012. Summary and management implications Palila Restoration Research, 1996−2012. Summary and management implications
The Palila Restoration Project was initiated in 1996 by the U.S. Geological Survey to assist government agencies mitigate the effects of realigning Saddle Road (Highway 200) through Palila Critical Habitat (U.S. Fish and Wildlife Service 1998, Federal Highway Administration 1999). Ecological research on the palila (Loxioides bailleui), an endangered Hawaiian forest bird, carried out by...
Authors
Paul C. Banko, Chris Farmer, Steve Dougill, Luanne Johnson
Particle-tracking investigation of the retention of sucker larvae emerging from spawning grounds in Upper Klamath Lake, Oregon Particle-tracking investigation of the retention of sucker larvae emerging from spawning grounds in Upper Klamath Lake, Oregon
This study had two objectives: (1) to use the results of an individual-based particle-tracking model of larval sucker dispersal through the Williamson River delta and Upper Klamath Lake, Oregon, to interpret field data collected throughout Upper Klamath and Agency Lakes, and (2) to use the model to investigate the retention of sucker larvae in the system as a function of Williamson River...
Authors
Tamara M. Wood, Susan A. Wherry, David C. Simon, Douglas F. Markle