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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 343 records · Page 19Linked to original sources
USGS2002

Landscape ecology of plague in the American southwest, September 19-20, 2000, Fort Collins, Colorado

During September 19-20, 2000, a workshop titled "Landscape Ecology of Plague in the American Southwest" was held in Fort Collins, Colorado. The workshop was funded by the U.S. Geological Survey (USGS)-Earth Surface Processes Team and sponsored by the USGS National Wildlife Health Center. Forty scientists and natural resource managers and administrators representing 8 federal agencies, 4 state agencies, 6 universities, and other local agencies and nongovernment organizations met to discuss historical and current status of plague in the United States, current activities in plague surveillance, research, and management in wildlife, and research and information needs relative to plague control and management. Eleven individual presentations on plague history, status, and trends; diagnostic technologies; epizootiological studies and observations; and control and management strategies and studies, followed by a panel discussion on the impact of plague on wildlife and ecosystems, led the way to extensive group discussions on important plague-related questions, issues and problems. Workshop attendees participated in identifying important research and information needs relevant to control and management of plague in wildlife, and in the process, established new cooperative and collaborative partnerships and enhanced existing relationships upon which future research and information needs can be met. The proceedings from this workshop are intended to be used by the natural resource managers and researchers from the various participating agencies, research facilities, as well as other stakeholders to aid in the development of future research and information programs and funding initiatives related to both zoonotic and sylvatic plague.

American Southwest↗
USGS1990

1986 Great Lakes Seismic refraction survey (GLIMPCE): Line A - refraction mode

In the fall of 1986, the Geological Survey of Canada (GSC), the United States Geological Survey (USGS), two Canadian universities -- University of Western Ontario and University of Saskatchewan, and four American universities -- Northern Illinois University, Southern Illinois University, University of Wisconsin-Madison and University of Wisconsin-Oshkosh participated in a major deep seismic experiment in Lake Superior under the GLIMPCE (Great Lakes International Multidisciplinary Program on Crustal Evolution) umbrella. This Open-File Report presents the seismic sections for line A, which was shot specifically for refraction recording. The main target for study by this line was the Mid-Continent Rift System. All recording stations, 31 in total (26 land stations and 5 OBSs), recorded energy from shots fired every two minutes (333 m spacing) by a tuned airgun array towed by a contracted ship along line A in Lake Superior. These data are the densest such data ever recorded in the continental North America over such distances. It is also unique since coincident seismic reflection and refraction are available.

Lake Superior↗
USGS2015

Desert wetlands—Archives of a wetter past

Scientists from the U.S. Geological Survey (USGS) are finding evidence of a much wetter past in the deserts of the American Southwest using a most unlikely source—wetlands. Wetlands form in arid environments where water tables approach or breach the ground surface. Often thought of as stagnant and unchanging, new evidence suggests that springs and wetlands responded dynamically to past episodes of abrupt climate change. Multiple cycles of deposition, erosion, and soil formation show that wetlands in the southwestern United States expanded and contracted many times during the past 35,000 years or so, before disappearing altogether as the last glacial period came to a close. USGS scientists are now studying the deposits to determine how closely conditions in the desert were tied to regional and global climate patterns in the past, and what it might mean for the fragile ecosystems in light of anticipated climate change in the future.

Nevada↗
USGS2000

Geology in the 1996 USGS seismic-hazard maps, central and eastern United States

The current (1996) national probabilistic seismic-hazard maps utilize information about geologic structure and tectonics of the central and eastern U.S. to compensate for uncertainty that arises from the short seismicity record. Geology was incorporated into the maps mainly as seven source zones that are delineated in three distinct ways. The North American stable continental region is divided into two large zones, the sparsely seismic Precambrian craton and the more active Phanerozoic rim. Five other source zones are much smaller - the Wabash Valley source zone is within the craton, whereas the Reelfoot Rift, eastern Tennessee, Charleston, and Charlevoix source zones are in the Phanerozoic rim of the continent. We document these zones and explain and justify their use. The seven zones provide a foundation from which we suggest a criterion for including more geology in future maps.

Seismological Research Letters↗
USGS1996

Strategic plan for the U.S. Geological Survey 1996 to 2005

During the past two decades profound changes have swept across the scientific, social, and political landscape in which the U.S. Geological Survey (the USGS) functions and to which it is inextricably linked. Core values that were institutionally forged and universally embraced in the past have been vigorously challenged and even vigorously assaulted. Political, economic, and societal forces that coalesced in 1995 threatened the very existence of the U.S. Geological Survey an organization that we long believed to be vital and important to the well-being of the American people and to the advancement of the earth sciences. The near abolishment of the USGS was averted largely by our customers. It was their understanding of the value of our work and their demand that we continue to provide our products and services that ensured our near-term survival.

Report↗
USGS2021

Detrital zircon record of magmatism and sediment dispersal across the North American Cordilleran arc system (28-48°N)

As zircon U-Pb geochronology has become a leading method in sediment provenance studies and basin analysis over the past 20 years, the volume of detrital zircon data made available in published literature has enabled researchers to go beyond source-to-sink provenance studies to explore increasingly complex geologic problems. In this review, we utilize the growing body of detrital zircon data acquired from Jurassic-Paleocene forearc and foreland basin strata of the North American Cordillera to investigate the Mesozoic to earliest Cenozoic evolution of the arc and its associated basins between 28°N and 48°N. Our compilation includes 830 detrital zircon samples (101,898 individual ages) from 70 studies published between 2000 and 2020. For comparative purposes, we also compile 1307 igneous zircon U-Pb ages that characterize the magmatic history of the arc. We place primary emphasis on detrital zircon ages between 251 and 56 Ma that we infer to be uniquely derived from magmatic sources in the arc. Informed by existing knowledge of magmatic, structural, and sedimentological processes that acted on the orogen, we investigate spatial and temporal trends in these “arc-derived zircon” to establish a detrital record of arc magmatism, investigate source-to-sink relationships between the arc and adjacent basins, and discuss controls on sediment dispersal across the orogen. Our review shows that compilations of detrital zircon data from the Cordilleran forearc and foreland basin systems are excellent proxies for arc magmatism because the basins are enriched in arc-derived zircon and compilations provide space- and time-integrated records of crystallization ages. The compiled detrital zircon data support a history of continuous arc magmatism throughout Mesozoic and earliest Cenozoic time, characterized by low-volume magmatism from Triassic-Early Jurassic time (~251–174 Ma) and episodic higher-volume magmatism from Middle Jurassic-Late Cretaceous time (~174–66 Ma). These trends elucidate the initiation and timing of magmatic events at the orogen-scale and corroborate our understanding of cyclic arc behavior. Detrital zircon distributions are spatially and temporally variable both within and across basins, which we discuss relative to topographic development of the orogen and attendant responses of sediment dispersal systems. Detrital zircon distributions in the forearc signal rapid transfer of sediment from the arc to basins dominantly via fluvial processes. In contrast, detrital zircon distributions across the foreland reflect the presence of topographic barriers in the hinterland region of the arc that effectively isolated parts of the foreland. The presence of hinterland topography in turn highlights the important role of ash-fall events in delivering arc-derived zircon to the foreland, underscoring the need to consider ash-fall processes in paleodrainage reconstructions. These broad regional trends, and in general the close linkage between orogenic process and sediment dispersal, emerge from our compilation because it averages out much of the local variability observed in studies of more limited geographic or temporal extent.

North American Cordilleran arc system↗
USGS1989

Lower Permian sediment-gravity-flow sequence, eastern California

The Lower Permian (middle Wolfcampian) Zinc Hill sequence, a 65- to 110-m-thick series of beds in the Owens Valley Group in east-central California, comprises sediment-gravity-flow deposits consisting of carbonate sediment that originated on, and siliciclastic sediment that may have been generally ponded behind, a carbonate shelf to the east and northeast. Thickness patterns and paleocurrent indicators show that the sediment forming this sequence was transported primarily southeastward and deposited in a southeast-trending, lobe-shaped body. Evidently, the sediment was carried from the shelf by sediment-gravity flows that travelled westward down the slope and then turned southeastward upon reaching a southeast-trending basin at the base of the slope. Data derived from the study of this basin, which paralleled the shelf edge and is thought to have formed parallel to a southeast-oriented segment of the Early Permian continental margin, constitute one of the most important arguments favoring a Pennsylvanian to Early Permian age of truncation of the western North American continental margin.

California↗
USGS2014

Appendix B—The work of the United States Geological Survey and cooperating agencies on ground water for war purposes

A report by O. E. MEINZER, published as Appendix B of the annual report of the Committee for 1942–43 [Trans. Amer. Geophys. Union, Part II, pp. 418–420, 1943], describes in some detail the previous work of the United States Geological Survey and cooperating agencies on ground water for war purposes. The geologists from the staff of the Geological Survey listed in that report and several other ground‐water geologists have served in the Army during the past year on water‐supply assignments. Only sketchy and unofficial information is as yet available concerning the activities of these geologists, but it is believed that they are now all engaged in overseas theaters of warfare and that their services in water‐supply and other technical work are of substantial value. In this service they have been supported by ground‐water maps and reports furnished by the Geological Survey for the different theaters.

Eos, Transactions, American Geophysical Union↗
USGS1982

Limits to northward drift of the Paleocene Cantwell Formation, central Alaska

Volcanic rocks of the Paleocene Cantwell Formation in central Alaska apparently originated at a paleolatitude of 83°N (α 95 = 9.7°), as indicated by paleomagnetic results. When compared with the Paleocene pole for the North American craton, the 95% confidence limits of the results suggest that terranes north of the Denali fault have moved no more than 550 km northward relative to the North American craton since Paleocene time.

Geology↗
USGS2001

Forest fragmentation and bird community dynamics: Inference at regional scales

With increasing fragmentation of natural areas and a dramatic reduction of forest cover in several parts of the world, quantifying the impact of such changes on species richness and community dynamics has been a subject of much concern. Here, we tested whether in more fragmented landscapes there was a lower number of area-sensitive species and higher local extinction and turnover rates, which could explain higher temporal variability in species richness. To investigate such potential landscape effects at a regional scale, we merged two independent, large-scale monitoring efforts: the North American Breeding Bird Survey (BBS) and the Land Use and Land Cover Classification data from the U.S. Geological Survey. We used methods that accounted for heterogeneity in the probability of detecting species to estimate species richness and temporal changes in the bird communities for BBS routes in three mid-Atlantic U.S. states. Forest breeding bird species were grouped prior to the analyses into area-sensitive and non-area-sensitive species according to previous studies. We tested predictions relating measures of forest structure at one point in time (1974) to species richness at that time and to parameters of forest bird community change over the following 22-yr-period (1975–1996). We used the mean size of forest patches to characterize landscape structure, as high correlations among landscape variables did not allow us to disentangle the relative roles of habitat fragmentation per se and habitat loss. As predicted, together with lower species richness for area-sensitive species on routes surrounded by landscapes with lower mean forest-patch size, we found higher mean year-to-year rates of local extinction. Moreover, the mean year-to-year rates of local turnover (proportion of locally new species) for area-sensitive species were also higher in landscapes with lower mean forest-patch size. These associations were not observed for the non-area-sensitive species group. These results suggest that landscape structure may influence forest bird communities at regional scales through its effects on the total number of species but also on the temporal rates of change in community composition. Evidence for higher rates of local extinction and turnover in more fragmented landscapes suggests that bird communities function as metapopulations at a regional scale, and points out the importance of colonizations and recolonizations from surrounding landscapes to local community dynamics. Further, our results illustrate that the methods used to estimate the community parameters can be a powerful statistical tool in addressing questions relative to the dynamics of communities.

Ecology↗
USGS2005

Geology of the Payette National Forest and vicinity, west-central Idaho

Before the Late Cretaceous, the eastern and western parts of the geologically complex Payette National Forest, as divided by the Salmon River suture, had fundamentally different geologic histories. The eastern part is underlain by Mesoproterozoic to Cambrian(?) rocks of the Laurentian (Precambrian North American) continent. Thick Mesoproterozoic units, which are at least in part equivalent in age to the Belt Supergroup of northern Idaho and western Montana, under-went Mesoproterozoic metamorphic and deformational events, including intrusion of Mesoproterozoic plutons. During the Neoproterozoic to early Paleozoic, the western edge of Laurentia was rifted. This event included magmatism and resulted in deposition of rift-related Neoproterozoic to Lower Cambrian(?) volcanic and sedimentary rocks above Mesoproterozoic rocks. The western part of the forest is underlain by upper Paleozoic to lower Mesozoic island-arc volcanic and sedimentary rocks. These rocks comprise four recognized island-arc terranes that were amalgamated and intruded by intermediate-composition plutons, probably in the Late Jurassic and Early Cretaceous, and then sutured to Laurentia along the Salmon River suture in the Late Cretaceous. The Salmon River suture formed as a right-lateral, transpressive fault. The metamorphic grade and structural complexity of the rocks increase toward the suture from both sides, and geochemical signatures in crosscutting plutonic rocks abruptly differ across the crustal boundary. Having been reactivated by younger structures, the Salmon River suture forms a north-trending topographic depression along Long Valley, through McCall, to the Goose Creek and French Creek drainages. During the last stages of metamorphism and deformation related to the suture event, voluminous plutons of the Idaho batholith were intruded east of the suture. An older plutonic series is intermediate in composition and preserved as elongated and deformed bodies near the suture and as parts of roof pendants to younger intrusions to the east. A younger magma series consists of undeformed, marginally peraluminous plutons that formed east of the suture after accretion. After suture-related compression, crustal extension resulted in voluminous volcanic and plutonic rocks of the Eocene Challis magmatic complex on the east side of the forest. Extension, from the Late Cretaceous to post-Miocene, uplifted the area of the Idaho batholith relative to the western part of the forest and formed dominant highlands along the Snake River. Extensional basins also formed such that, in the Miocene, the Columbia River Basalt Group and related basaltic lavas flowed over most of the lower elevations on the western side of the forest and redirected erosional debris into north-trending, fault-controlled drainages and young sedimentary basins.

Idaho↗
USGS2020

2018 and 2023 U. S. National Seismic Hazard Models

During 2017-2018, the National Seismic Hazard Model (NSHM) was updated by incorporating (1) new median ground motion models, new estimates of their epistemic uncertainties and aleatory variabilities, and new soil amplification factors for the central and eastern U.S., (2) amplification of long-period ground motions in deep sedimentary basins in the Los Angeles, San Francisco, Seattle, and Salt Lake City areas, (3) an updated seismicity catalog, which includes new earthquakes that occurred between 2012 and 2017, and (4) improved computer code and implementation details. Results show significantly increased ground shaking in many (but not all) locations across the central and eastern U.S., and increased ground shaking in the four urban areas (listed above) that overlie deep sedimentary basins in the western U.S. During 2019-2023, the NSHM will consider additional updates for the 2023 NSHM including: 3D simulations in urban areas of Los Angeles and Seattle, additional soil amplification models for other urban areas (e.g., eastern and southern coastal plains of the U.S., Reno, and Las Vegas), non-ergodic ground motion models that reconsider epistemic and aleatory uncertainty, topographic amplification, and new geological and geodetic models for faults. These maps will be considered by the Building Seismic Safety Council, American Society of Civil Engineers, and International Building Code committees for inclusion in upcoming building codes. Due to population growth, more people live and work in areas of moderate or high seismic hazard than ever before, leading to higher risk of undesirable consequences from future ground shaking.

conterminous United States↗
USGS1988

Codes for the identification of aquifer names and geologic units in the United States and the Caribbean outlying areas

This standard provides codes to be used for the identification of aquifer names and geologic units in the United States, the Caribbean and other outlying areas. Outlying areas include Puerto Rico, the Virgin Islands, American Samoa, the Midway Islands, Trust Territories of the Pacific Islands, and miscellaneous Pacific Islands. Each code identifies an aquifer or rock-stratigraphic unit and its age designation. The codes provide a standardized base for use by organizations in the storage, retrieval, and exchange of ground-water data; the indexing and inventory of ground-water data and information; the cataloging of ground-water data acquisition activities; and a variety of other applications.

Circular↗
USGS1985

Codes for the identification of aquifer names and geologic units in the United States and the Caribbean outlying areas

This standard provides codes to be used for the identification of aquifer names and geologic units in the United States, the Caribbean and other outlying areas. Outlying areas include Puerto Rico, the Virgin Islands, American Samoa, the Midway Islands, Trust Territories of the Pacific Islands, and miscellaneous Pacific Islands. Each code identifies an aquifer or rock-stratigraphic unit and its age designation. The codes provide a standardized base for use by organizations in the storage, retrieval, and exchange of ground-water data; the indexing and inventory of ground-water data and information; the cataloging of ground-water data acquisition activities; and a variety of other applications.

Circular↗
USGS2019

Natural hazards and mineral commodity supply: Quantifying risk of earthquake disruption to South American copper supply

Mineral resources, and their mining and enrichment operations, are not equally distributed across Earth. The concentration of mineral supply in certain regions, owing to the geology or geography of the mineral resource, raises the level of risk related to supply disruption. Where mineral production coincides with areas prone to natural hazards, supply may be especially at risk. However, the level of risk that natural hazards pose to mineral supply has yet to be quantified on a global or regional scale. Using copper in South America as a case study, this paper offers methods for quantifying (i) the coincidence of mineral production and seismic hazards, and (ii) the Expected Annual Disruption (EAD) of the mineral supply from earthquakes. The first of these methods indicates that, of the 101 copper producing facilities in South America considered, 76 are located within an area of high seismic hazard, taken here as the area with>85% chance of exceeding Modified Mercalli Intensity VI earthquake shaking in 50 years. Collectively, the 76 facilities comprise 82%, 87%, and 91% of the 2015 South American mine production, smelter capacity, and refinery capacity, respectively. For each of the 101 facilities, the second method calculates the EAD using a full earthquake shaking hazard forecast at the location, the annualized copper production of the facility, and models of the vulnerability of that production to shaking. The EADs are summed by country, here within South America, as a demonstration of how supply risk could eventually be quantified globally. Consideration of two illustrative vulnerability models shows that future work is needed to determine percentages of disruption to mineral production for different levels of earthquake shaking. Ultimately, the methods presented herein could be applied to other mineral commodities and/or adapted for other natural hazards, and the resulting EADs could be summed. Results from these methods could be used to focus more detailed risk assessments where the risk is highest.

Resources Policy↗
USGS2012

Lidar base specification

In late 2009, a $14.3 million allocation from the American Recovery and Reinvestment Act (ARRA) for new light detection and ranging (lidar) elevation data acquisition prompted the U.S. Geological Survey (USGS) National Geospatial Program (NGP) to develop a common minimum specification for all lidar data acquired for The National Map. Released as a working draft in 2010 and formally published in 2012, the USGS–NGP Lidar Base Specification (LBS) was quickly embraced by numerous States, counties, and foreign countries as the foundation for their own lidar specifications. Prompted by a growing appreciation for the wide applicability and inherent value of lidar, a consortium of Federal agencies commissioned the National Enhanced Elevation Assessment (NEEA) study in 2010 to quantify the costs and benefits of a national lidar program. Published in 2012, the NEEA report documented a substantial return on such an investment, defined five quality levels (QL) for elevation data, and recommended an 8-year collection cycle of QL2 lidar data as the optimum balance of benefit and affordability. In response to the study, the USGS–NGP established the 3D Elevation Program (3DEP) in 2013 as the interagency vehicle through which the NEEA recommendations could be realized. Lidar is a quickly evolving technology and much has changed in the industry since the previous version of the Lidar Base Specification (LBS) was published. Lidar data have improved in accuracy and spatial resolution, the American Society for Photogrammetry and Remote Sensing has revised the geospatial accuracy standards, industry standard file formats have been expanded, additional applications for lidar have become accepted, and the need for interoperable data across collections has been realized. This revision to the LBS addresses some of those changes and provides continued guidance towards a nationally consistent lidar dataset. Note Future versions of the Lidar base specification will be released online at https://www.usgs.gov/3DEP/lidarspec .

Techniques and Methods↗
USGS2019

3D geologic framework for use with the U.S. Geological Survey National Crustal Model, Phase 1—Western United States

A 3D geologic framework is presented here as part of the U.S. Geological Survey National Crustal Model for the western United States, which will be used to improve seismic hazard assessment. The framework is based on 1:250,000 to 1:1,000,000-scale state geologic maps and depths of multiple subsurface unit boundaries. The geology at or near the Earth’s surface is based on published maps with modifications to remove discontinuities across state borders. Extrapolation of rock type and age in the subsurface is achieved by iterative stripping of units of a given age, nearest neighbor interpolation of the remaining units, and constraints on basement geology. The subsurface depth of the interfaces between units is determined by a range of models with varying quantity and quality of constraints. Bedrock depth is derived primarily from a proxy model with added geophysical constraint in some areas. The depths to the base of Cenozoic and Phanerozoic sedimentary and extrusive volcanic rocks are constrained by geophysical methods in many areas. Elsewhere, a simple method is used to estimate their subsurface depth based on the distance to the edge of the geologic units. The remaining continental units are evenly distributed above, below, and between depending on age. The oceanic crust is treated as a simple four-layer model with the added complexity of subduction beneath the North American plate along the Cascadia subduction zone. Refinements to this technique may be accomplished in future versions of the model with more specific information including the location of faults to produce discontinuities in geologic structure and additional information obtained from boreholes and geophysical studies. Further improvements to the geologic framework may be made by incorporating information from more local studies, for example, hydrogeologic studies.

Open-File Report↗