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USGS2004

Urban growth in American cities : glimpses of U.S. urbanization

The Earth's surface is changing rapidly. Changes are local, regional, national, and even global in scope. Some changes have natural causes, such as earthquakes or drought. Other changes, such as urban expansion, agricultural intensification, resource extraction, and water resources development, are examples of human-induced change that have significant impact upon people, the economy, and resources. The consequences that result from these changes are often dramatic and widespread (Buchanan, Acevedo, and Zirbes, 2002) It is the role of the U.S. Geological Survey (USGS) to provide useful and relevant scientific information both to the agencies within the Department of the Interior and to the Nation in general. In an effort to comply with this task, USGS scientists are assessing the status of, and the trends in, the Nation's land surface. This assessment provides useful information for regional and national land use decisionmaking. This knowledge can be used to deal with issues of significance to the Nation, such as quality-of-life, ecology of urban environments, ecosystem health, ecological integrity, water quality and quantity concerns, resource availability, vulnerability to natural hazards, safeguards to human health, air and land quality, and accessibility to scientific information. Results of these assessments can also be analyzed to reveal rates and trends in land use change. Results from urban growth studies provide a firm foundation for continuing research that explores the consequences of human modification of the landscape. The USGS seeks to illustrate and explain the spatial history of urban growth and corresponding land use change. Scientists are studying urban environments from a regional perspective and a time scale of decades to measure the changes that have occurred in order to help understand the impact of anticipated changes in the future. Within this booklet are pairs of images of selected urbanized regions from across the Nation. These image pairs illustrate the transformation that these areas have undergone over two decades. Specifically, they depict changes in the extent of urban land. Each change pair is composed of one image from the 1970s and one image from the 1990s. Accompanying each image pair is a brief historical geography of factors that helped facilitate major changes that have occurred since the founding of the main city and the consequences and challenges of regional urban growth. The goal of this publication is to provide an illustration of urban change that is easily understood by a broad audience. The images used throughout this booklet were generated from land cover data developed by the USGS. The data sources include the Geographic Information Retrieval and Analysis System (GIRAS) for the 1970s images and the National Land Cover Dataset (NLCD) for the 1990s images. GIRAS digital maps are based on photointerpretations completed in the mid-1970s. The NLCD is a land cover dataset for the conterminous United States based on 1992 Landsat thematic mapper (TM) satellite imagery and supplemental data (fig. 1a and fig. 1b). The USGS distributes both of these land use and land cover digital datasets. The images were developed by using a geographic information system (GIS). The GIRAS and NLCD datasets were used to identify urban land within each region. In the final images all urban areas are shown in red. A shaded-relief map of each region was used to display the topographic context of the red polygon coverage. For all of these images, urban land is defined as areas transformed into a built-up environment for human use. It includes residential areas, commercial and industrial developments, transportation features, and institutions.

Circular↗

USGS2010

Topographic Science

The mission of U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center Topographic Science is to establish partnerships and conduct research and applications that facilitate the development and use of integrated national and global topographic datasets. Topographic Science includes a wide range of research and applications that result in improved seamless topographic datasets, advanced elevation technology, data integration and terrain visualization, new and improved elevation derivatives, and development of Web-based tools. In cooperation with our partners, Topographic Science is developing integrated-science applications for mapping, national natural resource initiatives, hazards, and global change science. http://topotools.cr.usgs.gov/.

Fact Sheet↗

USGS1968

Subsurface geology of the Silent Canyon caldera, Nevada Test Site, Nevada

Deep drilling in the vicinity of Silent Canyon on eastern Pahute Mesa, Nevada, has revealed a Tertiary volcanic section locally thicker than 14,000 feet. The area drilled covers most of the Silent Canyon caldera and some of the surrounding area. The caldera is rudely elliptical in plan and measures 10 by 14 miles. Except on its east edge, the caldera is completely obscured by younger volcanic rocks, including ash-flow sheets from several other centers. The structure, originally inferred from surface mapping and a 20-mgal gravity low, has been confirmed by drilling at 21 sites. Petrographic, chemical, and magnetic studies of more than 4,000 feet of drill core have revealed a complex sequence of volcanic rocks. Precaldera rocks include thick talc-alkalic lavas and tuffs. Peralkaline lavas and tuffs of the Silent Canyon center include the Belted Range Tuff (13-14 m.y.), eruption of which resulted in caldera collapse. The Belted Range Tuff has been downdropped 5,000-7,000 feet in the caldera. Subsequently, the depression was partially filled in the eastern part by genetically related peralkaline lavas and tuffs and in the western part by later calc -alkaline lavas and tuffs apparently genetically unrelated to the peralkaline rocks of the Silent Canyon center. Renewed subsidence probably occurred during their eruption. Isopach maps of younger tuffs show that the caldera was topographically low during deposition of later (12.5-7 m.y.) ash-flow sheets from other volcanic centers.

Nevada↗

USGS1977

Slope angle distribution of coal beds with strippable reserves

Slope angles were determined in representative strip mining areas of Arizona, Colorado, Illinois, Kentucky, Maryland, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wyoming by personnel of the U.S. Geological Survey to provide the Strip Mining Task Force, assembled by the Council of Environmental Quality, with data relating to the slope angle distribution of coal beds with strippable reserves. For the purpose of this study, slope determinations were made for 22 counties (table 1), selected by the Strip Mining Task Force, for coal beds known to contain strippable reserves as reported by Bureau of Mines Information Circular 8531, "Strippable Reserves of Bituminous Coal and Lignite in the United States." Available geologic maps that delineated coal bed outcrop lines on a topographic base were utilized for most slope angle determinations and coal resource reports provided additional data concerning the areas likely to contain recoverable coal reserves in the selected beds. The angles of slopes along which these coal beds occur were determined by measuring the spacing of topographic contour lines and were assigned to the appropriate slope categories selected for this purpose by the Strip Mining Task Force as follows: (A) 0-10°, (B) 10°-15°, (C) 15°-20°, (D) 20°-25°, and (E) 25°+. The overall sampling technique and measurement procedure are described in the following section and modification to this approach, necessitated by the availability and distribution of data, are described for each county. A list of source material used in compiling slope angles, slope distribution tables, and histograms are also included for each county.

Open-File Report↗

USGS2005

Analysis of multi-temporal geospatial data sets to assess the landscape effects of surface mining

Geospatial data sets, especially digital elevation data, have proven useful for characterizing and analyzing land surface conditions. Digital elevation models are routinely used for describing the morphology of the land surface in terms of slope gradient and aspect. Additionally, the elevation data are useful for deriving parameters that describe the local drainage conditions such as watersheds and stream channels. When the element of time is added to the analysis through the use of multi-temporal topographic data, the effects of changes to the physical shape of the land surface may be studied. Such is the case with analysis of historical (pre-mining) and recent (post-mining) topographic and other geospatial data sets, including land cover maps derived from remote sensing. Nationwide geospatial data sets now exist with the required spatial and temporal resolution that allow for assessment of the effects of surface mining operations. Changes to the local landscape morphology are readily identified, and the effects to the surface drainage features are quantifiable, such as changes to local relief and drainage pattern and the total length of affected streams. Additionally, the visual impact of the movement of rock and soil materials may be assessed through viewshed analysis. Examples in both Appalachian and Western coalfields show the usefulness of analyzing detailed historical and recent geospatial data sets to better map and describe the effects of surface mining.

Kentucky↗

USGS2010

Terrestrial Ecosystems of the Conterminous United States

The U.S. Geological Survey (USGS), with support from NatureServe, has modeled the potential distribution of 419 terrestrial ecosystems for the conterminous United States using a comprehensive biophysical stratification approach that identifies distinct biophysical environments and associates them with known vegetation distributions (Sayre and others, 2009). This standardized ecosystem mapping effort used an ecosystems classification developed by NatureServe (Comer and others, 2003). The ecosystem mapping methodology was developed for South America (Sayre and others, 2008) and is now being implemented globally (Sayre and others, 2007). The biophysical stratification approach is based on mapping the major structural components of ecosystems (land surface forms, topographic moisture potential, surficial lithology, isobioclimates and biogeographic regions) and then spatially combining them to produce a set of unique biophysical environments. These physically distinct areas are considered as the fundamental structural units ('building blocks') of ecosystems, and are subsequently aggregated and labeled using the NatureServe classification. The structural footprints were developed from the geospatial union of several base layers including biogeographic regions, isobioclimates (Cress and others, 2009a), land surface forms (Cress and others, 2009b), topographic moisture potential (Cress and others, 2009c), and surficial lithology (Cress and others, in press). Among the 49,168 unique structural footprint classes that resulted from the union, 13,482 classes met a minimum pixel count threshold (20,000 pixels) and were aggregated into 419 NatureServe ecosystems using a semiautomated labeling process based on rule-set formulations for attribution of each ecosystem. The resulting ecosystems are those that are expected to occur based on the combination of the bioclimate, biogeography, and geomorphology. Where land use by humans has not altered land cover, natural vegetation assemblages are expected to occur, and these are described in the ecosystems classification. The map does not show the distribution of urban and agricultural areas - these will be masked out in subsequent analyses to depict the current land cover in addition to the potential distribution of natural ecosystems. This map depicts the smoothed and generalized image of the terrestrial ecosystems dataset. Additional information about this map and any data developed for the ecosystems modeling of the conterminous United States is available online at: http://rmgsc.cr.usgs.gov/ecosystems/.

Scientific Investigations Map↗

USGS1994

Reconnaissance geologic mapping of a portion of the rain‐forest‐covered Guiana Shield, Northwestern Brazil, using SIR-B and digital aeromagnetic data

This paper documents the result of an integrated analysis of spaceborne radar (SIR-B) and digital aeromagnetic data carried out in the heavily forested Guiana Shield. The objective of the research is to interpret the geophysical data base to its limit to produce a reconnaissance geologic map as an aid to ground work planning in a worst‐case setting. Linear geomorphic features were identified based on the interpretation of the SIR-B image. Digital manipulation of aeromagnetic data allowed the development of a color‐shaded relief map of reduced‐to‐pole magnetic anomalies, a terrace‐magnetization map, and a map showing the location of maximum values of the horizontal component of the pseudogravity gradient (magnetization boundary lines). The resultant end product was a reconnaissance geologic map where broad terrane categories were delineated and geologic faults with both topographic and magnetic expression were defined. The availability of global spaceborne radar coverage in the 1990s and the large number of existing digital aeromagnetic surveys in northwestern Brazil indicate that this approach can be potentially useful for reconnaissance geologic mapping elsewhere in the Guiana Shield.

Geophysics↗

USGS2024

Parsimonious high-resolution landslide susceptibility modeling at continental scales

Landslide susceptibility maps are fundamental tools for risk reduction, but the coarse resolution of current continental-scale models is insufficient for local application. Complex relations between topographic and environmental attributes characterizing landslide susceptibility at local scales are not transferrable across areas without landslide data. Existing maps with multiple susceptibility classifications under-represent landslide potential in moderate and gently sloping terrain. We leverage an extensive landslide database ( N = 613,724), a high-resolution digital elevation model (10-m), and high-performance computing resources, to develop a new nationwide susceptibility map for the contiguous United States, Hawaii, Alaska, and Puerto Rico. We calculate four alternative linear and nonlinear thresholds of topographic slope and relief using an objective split-sample calibration. We down-sample our results to a 90-m grid to account for uncertainty in the digital elevation model and landslide position, and evaluate these thresholds' ability to differentiate areas of greater susceptibility. The less conservative nonlinear model optimally balances our priorities of capturing observed landslides (99%) while minimizing area covered by susceptible terrain (43%). Independent evaluation with four statewide landslide inventories ( N = 172,367) reinforces our model selection but highlights spatially variable performance. Therefore, we propose a novel approach to susceptibility classification using the concentration of landslide-prone terrain within each down-sampled grid. While landslides are possible within any cells containing susceptible terrain, those with the highest concentration capture the majority of observed landslides. Our new map characterizes landside susceptibility more consistently than prior models; our transparent classification approach also provides flexibility for accommodating different tolerances in risk reduction measures.

AGU Advances↗

USGS2022

Geologic map of the Stibnite mining area, Valley County, Idaho

The Stibnite mining area, as used herein, is bounded by the map extent that includes the Yellow Pine, West End, and Hangar Flats ore bodies. Other ore bodies are nearby, but the purpose of this map is to offer a detailed (1:8,000 scale) geologic map with new cross sections in the immediate area of Stibnite, Idaho. This geologic map is very similar to the Stibnite quadrangle map (Stewart and others, 2016) particularly the units and structure descriptions, because of the overlap of map extent. The new work by the author includes: (1) the topographic lines generated from the LiDAR base (courtesy of Midas Gold Corporation); (2) additional structural measurements; (3) revision of geologic unit contact placements particular around West End and Stibnite pits among other locations; and (4) seven new cross sections. New structural measurements from field work account for 20 percent of measurements shown with the remaining from Midas Gold Corp., Smitherman (1985), and the Stibnite quadrangle map (Stewart and others, 2016). Locations of many shallow features in the cross sections are controlled by core logs of 48 drillholes provided by Midas Gold Corp. The logs include dike placement, dike to plutonic bodies relationships, metasedimentary body localities, and dips of stratigraphic units. The law of sines was used to calculate dip of contacts between metasedimentary units for each cross section. Other features at depth in the cross sections are schematic based on nearby surface features and overall geologic interpretation. The map area contains metamorphosed sediments of Neoproterozoic and Paleozoic age within the Stibnite roof pendant. This rock package is open to tightly folded and reached lower amphibolite facies metamorphism during the Cretaceous Period. Most of the metasedimentary rocks are nearly vertical to overturned and young to the southwest, except on the southwestern flank of the Garnet Creek syncline. Pulses of the Idaho batholith granitoids intruded the metasedimentary units found in the Stibnite roof pendant. Faulting with apparent reverse, normal, and/or strike-slip offset are all present within the map area. Mineralization is largely fault controlled with some stratigraphic control. Volumetrically minor dikes, sills, and small intrusions are of Eocene age, and these intrusions are mostly depicted on the cross sections. Quaternary surficial deposits occur in stream beds and glaciated areas. Field work was conducted during the summers of 2013, 2015, and 2016. For consistency with recent research, most of the Stibnite quadrangle geologic map units (Stewart and others, 2016) are used for this geologic map. Intrusive units Kqd and Tba are new. The additional geologic mapping by the authors and compilation of detailed geologic maps from Midas Gold Corp. enhanced resolution. Cross sections incorporated drill core data including rock type, unit thickness, and oriented structural measurements offering detailed subsurface control. Data access was courtesy of Midas Gold Corp. Reed S. Lewis, Russell V. Di Fiori, and Claudio Berti provided constructive reviews that significantly improved this maps and cross sections. Previous studies that focus on mineralization include Schrader and Ross (1925), Currier (1935), White (1940), Cooper (1951), Cookro and others (1988), and more recently Gillerman and others (2019). Digital map files are available online (Wintzer, 2022).

Idaho↗

USGS2023

New high resolution airborne geophysical surveys in Nevada And California for geothermal and mineral resource studies

The U.S. Geological Survey (USGS) and the Department of Energy (DOE) are collaborating to acquire high-resolution airborne magnetic and radiometric data to support geologic and geophysical mapping and modeling that will assist geothermal and critical mineral studies. Coordinated with these efforts are programs supporting geologic mapping and airborne LiDAR (light detection and ranging) surveys that yield detailed surface topographic models of the terrain over the same regions spanned by the geophysical surveys. The collaboration leverages resources from the USGS and DOE to acquire large regional datasets that will provide fundamental data necessary to map surface and subsurface geology and structure to benefit mineral and resource program objectives of both agencies. Such regionally uniform datasets are important for geothermal research to assist in identifying geologically favorable settings and as invaluable inputs in predictive models targeting undiscovered resources that use knowledge-driven (e.g., play fairway analysis) or data-driven approaches (e.g., machine-learning methods) to reduce risk associated with resource exploration. These data will also serve a wide range of other related activities from hazard (earthquake, volcano, landslide, environmental) and resource (water, mineral, energy) studies, to mapping and land management. Surveys were conducted in two areas that were selected because they host substantial geothermal and mineral potential in California and Nevada. The data will aid several ongoing USGS and DOE projects aimed at characterizing geothermal and mineral systems, understanding the factors controlling their occurrence, and improving future national resource assessments. The first of these surveys (referred to as GeoDAWN) was collected over northern and western Nevada and eastern California and spans areas of major resource potential associated with the Walker Lane and western Great Basin. This includes Clayton Valley, which hosts substantial lithium brine and clay resources, and the Humboldt Mafic Complex, which constitutes a potentially important resource of critical minerals (including cobalt, rare earth elements, platinum group elements, iron, chromium, nickel, and copper). The second survey area (referred to as GeoFlight) is focused over the Salton Trough in southern California that contains some of the largest and hottest known hydrothermal systems in the world, as well as a substantial lithium brine resource that could potentially meet the nation’s lithium demand for electric vehicles. Data from both surveys will be made publicly available through USGS publications and online data repositories. Future efforts under this collaboration are presently being evaluated and may involve acquisition of other data sets such as airborne gravity, electromagnetic or hyperspectral data to address research targets.

Conference Paper↗

USGS2014

Multi-temporal mapping of a large, slow-moving earth flow for kinematic interpretation

Periodic movement of large, thick landslides on discrete basal surfaces produces modifications of the topographic surface, creates faults and folds, and influences the locations of springs, ponds, and streams (Baum, et al., 1993; Coe et al., 2009). The geometry of the basal-slip surface, which can be controlled by geological structures (e.g., fold axes, faults, etc.; Revellino et al., 2010; Grelle et al., 2011), and spatial variation in the rate of displacement, are responsible for differential deformation and kinematic segmentation of the landslide body. Thus, large landslides are often composed of several distinct kinematic elements. Each element represents a discrete kinematic domain within the main landslide that is broadly characterized by stretching (extension) of the upper part of the landslide and shortening (compression) near the landslide toe (Baum and Fleming, 1991; Guerriero et al., in review). On the basis of this knowledge, we used photo interpretive and GPS field mapping methods to map structures on the surface of the Montaguto earth flow in the Apennine Mountains of southern Italy at a scale of 1:6,000. (Guerriero et al., 2013a; Fig.1). The earth flow has been periodically active since at least 1954. The most extensive and destructive period of activity began on April 26, 2006, when an estimated 6 million m3 of material mobilized, covering and closing Italian National Road SS90, and damaging residential structures (Guerriero et al., 2013b). Our maps show the distribution and evolution of normal faults, thrust faults, strike-slip faults, flank ridges, and hydrological features at nine different dates (October, 1954; June, 1976; June, 1991; June, 2003; June, 2005; May, 2006; October, 2007; July, 2009; and March , 2010) between 1954 and 2010. Within the earth flow we recognized several kinematic elements and associated structures (Fig.2a). Within each kinematic element (e.g. the earth flow neck; Fig.2b), the flow velocity was highest in the middle, and lowest in the upper and lower parts. As the velocity of movement initiated and increased, stretching of the earth flow body induced the formation of normal faults. Conversely, decreasing velocity and shortening of the earth flow induced the formation of thrust faults. A zone with relatively few structures, bounded by strike-slip faults, was located between stretching and shortening areas. These kinematic elements indicate that the overall earth flow was actually composed of numerous linked internal earth flows, with each internal flow having a distinct pattern of structures representative of stretching and shortening (Guerriero et al., in review). These observations indicated that the spatial variation in movement velocity associated with each internal earth flow, mimicked the pattern of movement for the overall earth flow. That is, the earth flow displayed a self-similar pattern at different scales. Furthermore, the presence of other structures such as back-tilted surfaces, flank-ridges, and hydrological elements provide specific information about the shape of the basal topographic surface. Our multi-temporal maps provided a basis for interpretation of the long-term kinematic evolution of the earth flow and the influence of the basal-slip surface on the earth flow movement. Our maps showed that main faults remained stationary through time, despite extensive mobilization and movement of material. This observation indicated that the slip-surface has remained relatively stationary since at least 1954.

Conference Paper↗

USGS2011

Geologic map of the Metis Mons quadrangle (V–6), Venus

The Metis Mons quadrangle (V–6) in the northern hemisphere of Venus (lat 50° to 75° N., long 240° to 300° E.) includes a variety of coronae, large volcanoes, ridge and fracture (structure) belts, tesserae, impact craters, and other volcanic and structural features distributed within a plains setting, affording study of their detailed age relations and evolutionary development. Coronae in particular have magmatic, tectonic, and topographic signatures that indicate complex evolutionary histories. Previously, the geology of the map region has been described either in general or narrowly focused investigations. Based on Venera radar mapping, a 1:15,000,000-scale geologic map of part of the northern hemisphere of Venus included the V–6 map region and identified larger features such as tesserae, smooth and hummocky plains materials, ridge belts, coronae, volcanoes, and impact craters but proposed little relative-age information. Global-scale mapping from Magellan data identified similar features and also determined their mean global ages with crater counts. However, the density of craters on Venus is too low for meaningful relative-age determinations at local to regional scales. Several of the coronae in the map area have been described using Venera data (Stofan and Head, 1990), while Crumpler and others (1992) compiled detailed identification and description of volcanic and tectonic features from Magellan data. The main purpose of this map is to reconstruct the geologic history of the Metis Mons quadrangle at a level of detail commensurate with a scale of 1:5,000,000 using Magellan data. We interpret four partly overlapping stages of geologic activity, which collectively resulted in the formation of tesserae, coronae (oriented along structure belts), plains materials of varying ages, and four large volcanic constructs. Scattered impact craters, small shields and pancake-shaped domes, and isolated flows superpose the tectonically deformed materials and appear to be the most youthful materials in the map region.

Scientific Investigations Map↗

USGS2008

The National Map product and services directory

As one of the cornerstones of the U.S. Geological Survey's (USGS) National Geospatial Program (NGP), The National Map is a collaborative effort among the USGS and other Federal, state, and local partners to improve and deliver topographic information for the Nation. It has many uses ranging from recreation to scientific analysis to emergency response. The National Map is easily accessible for display on the Web, as products, and as downloadable data. The geographic information available from The National Map includes orthoimagery (aerial photographs), elevation, geographic names, hydrography, boundaries, transportation, structures, and land cover. Other types of geographic information can be added to create specific types of maps. Of major importance, The National Map currently is being transformed to better serve the geospatial community. The USGS National Geospatial Program Office (NGPO) was established to provide leadership for placing geographic knowledge at the fingertips of the Nation. The office supports The National Map , Geospatial One-Stop (GOS), National Atlas of the United States ® , and the Federal Geographic Data Committee (FGDC). This integrated portfolio of geospatial information and data supports the essential components of delivering the National Spatial Data Infrastructure (NSDI) and capitalizing on the power of place.

Fact Sheet↗

USGS2004

Limits of mountain and continental glaciations east of the Continental Divide in northern Montana and north-western North Dakota, U.S.A.

This chapter provides an overview of the limits of glaciations and glacial history in, and east and south-east of, Glacier National Park, Montana, and on the Northern Plains further east in Montana and north-western North Dakota. The term “Laurentide glacier” was applied to a continental ice sheet east of the Rocky Mountains in North America. It describes Laurentide Ice Sheet as any Quaternary continental ice sheet east of the Rocky Mountains in the United States and Canada. Laurentide till refers to till deposited by a Laurentide Ice Sheet. A Laurentide continental ice sheet is distinguished from a Cordilleran continental ice sheet in the Cordilleran region in parts of Washington, Idaho, and Montana in the United States and in adjacent Canada. Clague indicated that Cordilleran Ice Sheets formed several times during the Pleistocene. The chapter also reviews that the base for the digital map is simplified. Selected hydrographic features, selected towns and cities, selected physiographic features, and a grid of 1° × 2° topographic quadrangles are included to aid the reader in location of the glacial limits and other features depicted here on other maps at different scales.

Montana, North Dakota↗

USGS2013

Linking phenology and biomass productivity in South Dakota mixed-grass prairie

Assessing the health of rangeland ecosystems based solely on annual biomass production does not fully describe plant community condition; the phenology of production can provide inferences on species composition, successional stage, and grazing impacts. We evaluate the productivity and phenology of western South Dakota mixed-grass prairie using 2000 to 2008 Moderate Resolution Imaging Spectrometer (MODIS) normalized difference vegetation index (NDVI) satellite imagery at 250 m spatial resolution. Growing season NDVI images were integrated weekly to produce time-integrated NDVI (TIN), a proxy of total annual biomass production, and integrated seasonally to represent annual production by cool (C3) and warm (C4) season species. Additionally, a variety of phenological indicators including cool season percentage of TIN were derived from the seasonal profiles of NDVI. Cool season percentage and TIN were combined to generate vegetation classes, which served as proxies of plant community condition. TIN decreased with precipitation from east to west across the study area. Alternatively, cool season percentage increased from east to west, following patterns related to the reliability (interannual coefficient of variation [CV]) and quantity of mid-summer precipitation. Cool season TIN averaged 76.8% of total. Seasonal accumulation of TIN corresponded closely (R2 > 0.90) to that of gross photosynthesis data from a carbon flux tower. Field-collected biomass and community composition data were strongly related to the TIN and cool season percentage products. The patterns of vegetation classes were responsive to topographic, edaphic, and land management influences on plant communities. Accurate maps of biomass production, cool/warm season composition, and vegetation classes can improve the efficiency of land management by adjusting stocking rates and season of use to maximize rangeland productivity and achieve conservation objectives. Further, our results clarify the spatial and temporal dynamics of phenology and TIN in mixed-grass prairie.

South Dakota↗

USGS2023

Active volcanism on the Arabian Shield—Geology, volcanology, and geophysics of northern Harrat Rahat and vicinity, Kingdom of Saudi Arabia

Active volcanic systems pose serious hazards to people and property including inundation and incineration by lava, blanketing by tephra (volcanic ash), exposure to noxious volcanic gases, and damage from shallow earthquakes triggered by ascending molten material (magma). To improve understanding of volcanism and associated seismicity on the western Arabia Plate, the Saudi Geological Survey and the U.S. Geological Survey conducted a multi-year investigation of the northern Harrat Rahat volcanic field adjacent to the city of Al Madīnah al Munawwarah, Kingdom of Saudi Arabia. Project components included creation of a high-resolution digital topographic base; interpretation of eruptive history supported by detailed geologic mapping, paleomagnetism, and abundant high-precision geochronology of volcanic deposits; assessments of eruptive styles and volcanic hazards by physical volcanology; investigation of the origins of magmas in the mantle and of their differentiation in the crust revealed by chemical and isotopic petrology; gravity and magnetotelluric surveys to reveal crustal structures and to search for magma reservoirs; and regional and local seismic tomography and analyses of seismic hazards. Project results are presented in this Professional Paper as chapters written for technical scientific audiences.

Professional Paper↗

USGS2023

The Saudi Geological Survey-U.S. Geological Survey northern Harrat Rahat project—Styles, rates, causes, and hazards of volcanism near Al Madīnah al Munawwarah, Kingdom of Saudi Arabia

Al Madīnah al Munawwarah↗

USGS2000

Sea-floor environments within Long Island Sound: A regional overview

Modern sea-floor sedimentary environments within the glaciated, topographically complex Long Island Sound estuary have been interpreted and mapped from an extensive collection of sidescan sonographs, bottom samples, and video-camera observations together with supplemental bathymetric, marine-geologic, and bottom-current data. Four categories of environments are present that reflect the dominant long-term processes of erosion or nondeposition; coarsegrained bedload transport; sediment sorting and reworking; and fine-grained deposition. (1) Environments of erosion or nondeposition contain exposures of glacial drift, coarse lag deposits, and possibly bedrock and include sediments which range from boulder fields to gravelly coarse-to-medium sands. (2) Environments of coarse-grained bedload transport are mantled by sand ribbons and sand waves and contain mostly coarse-to-fine sands with only small amounts of mud. (3) Environments of sediment sorting and reworking comprise both uniform and heterogeneous sediment types and contain variable amounts of fine sand and mud. (4) Environments of fine-grained deposition are blanketed by muds and sandy muds. The patchy distribution of sedimentary environments within Long Island Sound reflects both regional and local changes in bottom processes. Regional changes are primarily the result of a strong, east-to-west decreasing gradient of bottom tidal-current speeds, coupled with the net (westward) estuarine bottom drift. The regional current regime has produced a westward succession of environments along the basin floor beginning with erosion or nondeposition at the narrow eastern entrance to the Sound, changing to an extensive area of coarse-grained bedload transport, passing into a contiguous band of sediment sorting, and ending with broad areas of fine-grained deposition in the central and western Sound. However, local changes in processes are superimposed on the regional conditions within the central and western parts of the basin and along the nearshore margins. Within the central and western basin, localized sedimentary environments are produced where the bottom flow is enhanced by, and interacts with, the bottom topography, whereas along the nearshore margins, they variously reflect wave-produced currents, the irregular bathymetry, the indented shoreline, and the proximal supply of sediments. Results from this study (1) confirm the high trapping efficiency of fine-grained sediments in the Sound, (2) suggest that fine-grained sediments accumulate at an average (regional) rate of 0.08 g/cm 2 /y , and (3) indicate that the postglacial delta in the eastern Sound was a significant source of fine-grained sediments now buried beneath depositional areas.

Connecticut, New York↗