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USGS1999

Digital mapping techniques '99 -- workshop proceedings

The Digital Mapping Techniques '99 (DMT'99) workshop was attended by 91 technical experts from 42 agencies, universities, and private companies, including representatives from 30 state geological surveys (see Appendix A ). This workshop was similar in nature to the first two meetings, held in June, 1997, in Lawrence, Kansas (Soller, 1997), and in May, 1998, in Champaign, Illinois (Soller, 1998a). This year's meeting was hosted by the Wisconsin Geological and Natural History Survey, from May 19 to 22, 1999, on the University of Wisconsin campus in Madison. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. When, based on discussions at the workshop, an attendee adopts or modifies a newly learned technique, the workshop clearly has met that objective. Evidence of learning and cooperation among participating agencies continued to be a highlight of the DMT workshops (see example in Soller, 1998b, and various papers in this volume). The meeting's general goal was to help move the state geological surveys and the USGS toward development of more cost-effective, flexible, and useful systems for digital mapping and geographic information systems (GIS) analysis. Through oral and poster presentations and special discussion sessions, emphasis was given to: 1) methods for creating and publishing map products (here, ìpublishingî includes Web-based release); 2) continued development of the National Geologic Map Database; and 3) progress toward building a standard geologic map data model. Especially to support the interest in map preparation and publication, five representatives of the GIS hardware and software vendor community were invited to participate. The three annual DMT workshops were coordinated by the AASG/USGS Data Capture Working Group, which was formed in August, 1996, to support the Association of American State Geologists and the USGS in their effort to build a National Geologic Map Database (see Soller and Berg, this volume, and http://ncgmp.usgs.gov/ngmdbproject/standards/datacapt/datacaptureWG.html ). The Working Group was formed because increased production efficiencies, standardization, and quality of digital map products were needed to help the Database, and the State and Federal geological surveys, provide more high-quality digital maps to the public.

Open-File Report↗
USGS1915

Springs of California

In 1903 the United States Geological Survey began an investigation of the underground water of California, generally with financial cooperation on the part of the State. Since that year ten papers on the underground water of the State have been issued by the Survey, each representing an investigation that has been completed. The field work which is to serve as the basis for two additional papers has also been done and the reports are in preparation. Investigations have been begun in two other areas in the State and their results will eventually be assembled and published. Since a period soon after the inception of the California work those responsible for its conduct have realized the desirability of a special study of the springs, particularly those which yield mineral waters and which are utilized to a greater or less extent by citizens of the State and by tourists as recreation and health resorts. It did not become practicable to begin this work until the summer of 1908, when Mr. G. A. Waring, who had assisted in some of the earlier California studies and had investigated for the Survey certain areas in southern Oregon and Washington, was assigned to the task of collecting and assembling the necessary data. California, with an area of 158,000 square miles, is the second largest State in the Union. It exhibits wide geographic diversity, since it includes the lowest area in the United States Death Valley, 276 feet below sea level and the highest Mount Whitney, 14,501 feet above the sea; and accompanying this geographic diversity there is a corresponding range in scenic effects, climate, and vegetation. The records obtained at meteorological stations in the Salton Sink indicate a maximum temperature of 130° in the shade, the highest of record within the continental United States. It is probable that minimum temperatures on the higher peaks, like Mount Whitney and Mount Shasta, approach the minimum within our boundaries. Rainfall records in the most arid sections of the southern deserts of the State represent the extreme of aridity in the United States, with averages of less than 3 inches per annum and periods of 12 months or more with only traces of rain, whereas the precipitation in northwestern California is very heavy, an annual average of close to 100 inches being recorded at a few stations in Mendocino and Del Norte counties. The immensity of the area of the State has made the collection of the field data required for the report a task of considerable magnitude, though its diversity has added greatly to the interest of the work. In the original plan it was estimated that two years of field studies would prove sufficient. Mr. Waring succeeded in visiting the more important localities during this period, although some of his examinations were, of necessity, rather cursory. In midsummer, 1910, after the completion of the field work and the assembling of the greater portion of his data in manuscript form he was called by the Government of Brazil to take charge of general water supply investigations in the northeastern arid portion of that South American republic. The task of reviewing, editing, and supplementing in some respects, the results of his studies was thus unavoidably left to others. This task was rendered light by the systematic form in which Mr. Waring's material was left. It was a matter of regret to Mr. Waring, as it has been to those associated with him, that the financial limitations which controlled his work made it impracticable to procure the large number of new analyses which are particularly important in a paper of this type, in which waters of unusual chemical characteristics are discussed. Such analyses as are available have been assembled from all possible sources and combined with those which were prepared especially in connection with this investigation. The result, although it is in some respects unsatisfactory, furnishes a basis for a general view of the characteristics of the spring waters and serves to permit, their classification in a general way. Mr. Herman Stabler has reviewed the chemical data and rearranged and interpreted the available analyses. It is hoped that the report, setting forth as it does the results of impartial observations upon one of the important present and more important prospective resources of the State, will prove of value to its citizens as well as to its visitors, and that the assembled material will not be without interest to physicians, chemists, geologists, and teachers who may have especial need for the information contained in the volume.

California↗
USGS1984

Ferromanganese crust resources in the Pacific and Atlantic Oceans

Ferromanganese crusts on raised areas of the ocean floor have joined abyssal manganese nodules and hydrothermal sulfides as potential marine resources. Significant volumes of cobalt-rich (about 1% Co) crusts have been identified to date within the US Exclusive Economic Zone (EEZ) in the Central Pacific: in the NW Hawaiian Ridge and Seamount region and in the seamounts in the Johnston Island and Palmyra Island regions. Large volumes of lower grade crusts, slabs, and nodules are also present in shallow ( greater than 1000 m) waters on the Blake plateau, off Florida-South Carolina in the Atlantic Ocean. Data on ferromanganese crusts have been increased by recent German and USGS cruises, but are still sparse, and other regions having crust potential are under current investigation. The authors discuss economic potentials for cobalt-rich crusts in the Central Pacific and Western North Atlantic oceans, with special reference to US EEZ areas. Additional research is needed before more quantitative resource estimates can be made.

Conference Paper↗
USGS2022

Subsampling large-scale digital elevation models to expedite geospatial analyses in coastal regions

Large-area, high-resolution digital elevation models (DEMs) created from light detection and ranging (LIDAR) and/or multibeam echosounder data sets are commonly used in many scientific disciplines. These DEMs can span thousands of square kilometers, typically with a spatial resolution of 1 m or finer, and can be difficult to process and analyze without specialized computers and software. Such DEMs often can be subsampled to expedite analysis with negligible impact on results for large-scale geospatial analyses. Subsampling can be achieved by creating a grid of points that specify the locations from which to extract elevation values from the DEM. This paper presents a method that can be used to accurately perform subsampling of large-scale, high-resolution DEMs using GIS software. This subsampling method was applied to two LIDAR-derived DEMs encompassing 242 km 2 of the northern Florida Reef Tract as an example application and to test subsampling accuracy. Results indicate that subsampling 1-m-resolution DEMs using a 2-m-spaced grid results in no significant difference in mean elevation or other basic statistics for analyses performed over multiple spatial scales ranging from 1 km 2 to 242 km 2 .

Journal of Coastal Research↗
USGS1973

Mars cartography: the 1:5,000,000 map series

This catalog illustrates the 1:5,000,000 series of Mars base maps being compiled as part of the Mariner 9 scientific data reduction effort. This effort is sponsored by four different Centers within the National Aeronautics and Space Administration: 1) The Jet Propulsion Laboratory, California Institute of Technology, 2) The Langley Research Center, 3) NASA Headquarters, and 4) The Planetology Programs Office at NASA Headquarters. The catalog will be updated periodically as new materials become available, and will eventually be expanded to include cartographic products at scales of 1:1, 000, 000 and 1:250,000. Detailed discussions of the many aspects of Mars cartography are given in papers listed in the bibliography. Only brief notes are given here to aid the reader's understanding of existing products. Data returned by Mariner 9 spacecraft permit detailed mapping of landforms with dimensions as small as 1 to 3 km over the entire surface of Mars. A few special areas can be mapped to show landforms with dimensions as small as 100 m. Prior to the use of spacecraft television, telescopic views of the planet resolved only light and dark markings having dimensions greater than 100 km. Topographic features as such have not been identified telescopically. It was not until the flights of Mariners 4, 6, and 7 that Martian surface topography was revealed. High resolution pictures taken by these spacecraft covered only 20% of theplanet. By chance, the areas photographed by these spacecraftconsisted mostly of cratered terrain and no data were obtained thatsuggested the presence of the spectacular volcanoes and canyonsrevealed by the first time by Mariner 9. Mariner 9 covered at least 70% of the surface of Mars with pictures resolving features 1 to 2 km in size and the remainder with pictures resolving features about 3 km in size. These pictures, therefore, are now the definitive sources of data for the cartography of Mars and, because of their completeness, are not likely to be surpassed in this decade or perhaps this century.

Open-File Report↗
USGS2001

Species and population variation to salinity stress in Panicum hemitomon, Spartina patens, and Spartina alterniflora: Morphological and physiological constraints

Panicum hemitomon, Spartina patens, and Spartina alterniflora are wide-spread dominant grasses of fresh, brackish, and salt marsh plant communities, respectively. Our previous research identified significant intraspecific variation in salt tolerance and morphology among populations within each species. In this study our objectives were to determine shorter-term physiological/biochemical responses to salinity stress and identify potential indicators of salt tolerance, with the ultimate goal of discerning similarities and differences in the mechanisms of salinity stress resistance. We subjected a subset of six populations within each species, ranging from high to low salt tolerance, to sublethal salinity levels (4, 20, and 30 ppt, respectively, for species) and monitored physiological and growth responses after 1 week (early harvest) and 5 weeks (late harvest). In all three species sublethal salinity levels generally resulted in significantly reduced net CO2 assimilation, leaf expansion, midday leaf xylem pressure, water use efficiency, and live and total biomass; and significantly increased leaf Na+/K+ ratio, leaf proline, leaf glycine betaine, leaf sucrose, root-to-shoot ratio, and dead:total aboveground biomass ratio. All three species displayed significant population (intraspecific) variation in net CO2 assimilation, leaf expansion, water use efficiency, midday leaf xylem pressure, leaf proline, leaf glycine betaine (except Panicum, where it could not be accurately determined), leaf Na+/K+ ratio, leaf sucrose, total plant biomass, dead:total aboveground biomass ratio, and root-to-shoot ratio. General indicators of salt tolerance (regardless of species) included high net CO2 assimilation rates and water use efficiencies, and low ratios of root-to-shoot and dead:total aboveground biomass. Factor analysis and a-priori linear contrasts revealed some unique differences between species in terms of the relative importance of morphology and physiology in explaining intraspecific variation in salt tolerance. Plant morphology (size attributes) were strongly associated with salt tolerance in P. hemitomon, weakly associated with salt tolerance in S. patens, and not associated with salt tolerance in S. alterniflora. Highly salt-tolerant populations of Spartina alterniflora displayed the greatest ion selectivity (lower leaf Na+/K+ ratios), which was not displayed by the other two species. These results suggest that plant size attributes can be very important in explaining population differences in salt tolerance in glycophytes, but may be independent of salt tolerance in halophytes, which have specialized physiological (and/or anatomical) adaptations that can confer salinity stress resistance through mechanisms such as selective ion exclusion and secretion. ?? 2001 Elsevier Science B.V. All rights reserved.

Conference Paper↗
USGS2008

Validation of exposure time for discharge measurements made with two bottom-tracking acoustic doppler current profilers

Previous work by Oberg and Mueller of the U.S. Geological Survey in 2007 concluded that exposure time (total time spent sampling the flow) is a critical factor in reducing measurement uncertainty. In a subsequent paper, Oberg and Mueller validated these conclusions using one set of data to show that the effect of exposure time on the uncertainty of the measured discharge is independent of stream width, depth, and range of boat speeds. Analysis of eight StreamPro acoustic Doppler current profiler (ADCP) measurements indicate that they fall within and show a similar trend to the Rio Grande ADCP data previously reported. Four special validation measurements were made for the purpose of verifying the conclusions of Oberg and Mueller regarding exposure time for Rio Grande and StreamPro ADCPs. Analysis of these measurements confirms that exposure time is a critical factor in reducing measurement uncertainty and is independent of stream width, depth, and range of boat speeds. Furthermore, it appears that the relation between measured discharge uncertainty and exposure time is similar for both Rio Grande and StreamPro ADCPs. These results are applicable to ADCPs that make use of broadband technology using bottom-tracking to obtain the boat velocity. Based on this work, a minimum of two transects should be collected with an exposure time for all transects greater than or equal to 720 seconds in order to achieve an uncertainty of ??5 percent when using bottom-tracking ADCPs. ?? 2008 IEEE.

Conference Paper↗
USGS1998

Modeling and management of water in the Klamath River Basin: overcoming politics and conflicts

The network flow model MODSIM, which was designed as a water quantity mass balance model for evaluating and selecting water management alternatives, has been applied to the Klamath River basin. A background of conflicting issues in the basin is presented. The complexity of water quantity model development, while satisfying the many stakeholders and involved special interest groups is discussed, as well as the efforts taken to have the technical model accepted and used, and overcome stakeholder criticism, skepticism, and mistrust of the government.

Oregon↗
USGS1963

General summary of effects of the drought in the Southwest: Chapter H in Drought in the Southwest, 1942-56

This final chapter of Prof. Paper 372 summarizes the results of a comprehensive study of drought in the Southwest, as reported in greater detail in chapters A-G. Chapter A presents some of the published and recorded conclusions concerning the basic meteorological factors that influence the patterns of precipitation in the Southwest, and describes the characteristics of the drought of 1942-56 as indicated by meteorologic records. Chapter B is a general discussion of the effects of that drought as shown by hydrologic data. Subsequent chapters (C-G) provide more detailed evaluations of the effects of drought in individual river basins and specific localities. The effects of drought are discriminated from water shortages due to other causes wherever possible. For this summary, the hydrologic units in the Southwest are classified according to type, and examples of each type are cited, but no attempt is made to summarize the effects of drought in every hydrologic unit in the Southwest, as was described in preceding parts of this report. The comprehensive study of drought has required analysis of the longest records available concerning all aspects of the water resources, with special attention to the 1942-56 period to ascertain similarities with earlier drought periods and contrasts with periods of greater precipitation. Despite the intended emphasis on drought, the studies have been almost as broad in scope as general studies of interrelations of the hydrologic cycle.

Southwestern United States↗
USGS2007

Antarctica: A Keystone in a Changing World--Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences. Santa Barbara, California, U.S.A.--August 26 to September 1, 2007

Overview: The International Symposium on Antarctic Earth Sciences (ISAES) is held once every four years to provide an international forum for presenting research results and new ideas and for planning future Antarctic geoscience research projects. This Tenth ISAES coincides with the International Polar Year (IPY; 50th Anniversary of the International Geophysical Year) and has been structured to showcase the great breadth of geoscience research being done in Antarctic regions by more than more than 100 institutions located in over 30 countries. The science program of the Symposium encompasses six broad themes that cover key topics on evolution and interactions of the geosphere, cryosphere and biosphere and their cross-linkages with past and historic paleoclimates. Emphasis is also on deciphering the climate records in ice cores, geologic cores, rock outcrops and those inferred from climate models. New technologies for the coming decades of geoscience data collection are also highlighted. Ten keynote presentations at the symposium outline the foundation for the research sessions of the symposium and the structure of the Online Proceedings and Proceedings Book for the Tenth ISAES. The ISAES is traditionally a cornerstone meeting for the Scientific Committee on Antarctic Research (SCAR). In recognition of the Tenth ISAES being held in the U.S. for the first time in 30 years and during IPY, the publication of the symposium proceedings is being handled as a special collaborative effort of the U.S. National Science Foundation, the U.S. Geological Survey, The National Academies Polar Research Board and The National Academies Press. The National Academies Polar Research Board oversees the activities of SCAR in the U.S. Special attention has been directed at publication formats for the symposium, to expedite the open and wide sharing of mature and preliminary research results presented in talks and posters at the Tenth ISAES. All symposium presentations are documented by a short Summary printed in the Symposium Program Booklet and either a short research paper or an extended abstract. The research papers and extended abstracts are compiled in this Online Proceedings and are replicated on a DVD-ROM that is placed in the back of the Tenth ISAES Proceedings Book. The Proceedings Book has printed versions of the keynote talks and an overview paper of the symposium. The short research papers and extended abstracts have been handled differently. Research papers present mature research results and syntheses. They have been peer-reviewed using standard journal procedures. Following revisions and acceptances by co-editors, the papers have been formatted for publication and proofread by authors. Each paper has been assigned a Digital Object Identification (DOI) number and separate html link, and posted online (as part of this USGS Open-File Report series) to ensure open and wide access to the research results. Extended abstracts focus on preliminary research results and have not been peer reviewed. They have had only minimal editorial review and revision. Authors have formatted and proofread their papers. Extended abstracts were not given DOI numbers and are included together in a separate chapter of this online Proceedings. USGS publications staff and Stanford-student editorial assistants indexed and compiled the PDF versions of the short research papers and extended abstracts for inclusion in this online Proceedings. USGS staff created the master DVD-ROM that contains a replica of the Online Proceedings for the Tenth ISAES, and provided the DVD-ROM copies that are included in the Tenth ISAES Proceedings Book published by The National Academies Press in the U.S. A team of more than 25 co-editors coordinated with the numerous authors and peer reviewers in handling the many research papers and extended abstracts that are included herein. Handling the large volume of short papers and extended abstracts, getting most of them onli

Open-File Report↗
USGS2010

Eruptions of Hawaiian volcanoes—Past, present, and future

Viewing an erupting volcano is a memorable experience, one that has inspired fear, superstition, worship, curiosity, and fascination since before the dawn of civilization. In modern times, volcanic phenomena have attracted intense scientific interest because they provide the key to understanding processes that have created and shaped more than 80 percent of the Earth’s surface. The active Hawaiian volcanoes have received special attention worldwide because of their frequent spectacular eruptions, which often can be viewed and studied with relative ease and safety. In January 1987, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO), then located on the caldera rim of Kīlauea, celebrated its 75th anniversary. To honor this anniversary, the U.S. Geological Survey (USGS) published Professional Paper 1350 , a comprehensive summary of the many studies on Hawaiian volcanism by USGS and other scientists through the mid-1980s. Drawing from the wealth of data contained in that volume, the USGS also published in 1987 the original edition of this general-interest booklet, focusing on selected aspects of the eruptive history, style, and products of two of the State of Hawaii’s active volcanoes—Kīlauea and Mauna Loa. A second edition of the booklet was published in 2010 to commemorate the Centennial of HVO (which occurred in January 2012), summarizing abundant new information gained since the January 1983 onset of Kīlauea’s middle East Rift Zone eruption at Pu‘u‘ō‘ō and the March 2008 beginning of Kīlauea’s summit lava-lake activity within Halema‘uma‘u. In this third edition, we include highlights from Kīlauea’s subsequent activity, including the 2018 eruption in the lower East Rift Zone—the largest and most destructive in at least 200 years—and associated summit-collapse events, the eruptions at Kīlauea’s summit since 2018, and the 2022 eruption of Mauna Loa, which occurred after 38 years of quiescence. It also considers new data leading to an improved history of Kīlauea’s explosive activity in the recent geologic past. This general-interest booklet is a companion to the one on Mount St. Helens volcano (southwestern Washington) first published in 1984, revised in 1990. Together, these publications illustrate the contrast between the two main types of volcanoes: shield volcanoes, such as those in the State of Hawaii, which generally are nonexplosive to weakly explosive; and composite volcanoes, such as Mount St. Helens in the Cascade Range, which generally erupt explosively.

Hawaii↗
USGS2016

Bed texture mapping in large rivers using recreational-grade sidescan sonar

The size-distribution and spatial organization of bed sediment, or bed ‘texture’, is a fundamental attribute of natural channels and is one important component of the physical habitat of aquatic ecosystems. ‘Recreational-grade’ sidescan sonar systems now offer the possibility of imaging, and subsequently quantifying bed texture at high resolution with minimal cost, or logistical effort. We are investigating the possibility of using sidescan sonar sensors on commercially available ‘fishfinders’ for within-channel bed-sediment characterization of mixed sand-gravel riverbeds in a debris-fan dominated canyon river. We analyzed repeat substrate mapping of data collected before and after the November 2014 High Flow Experiment on the Colorado River in lower Marble Canyon, Arizona. The mapping analysis resulted in sufficient spatial coverage (e.g. reach) and resolutions (e.g. centrimetric) to inform studies of the effects of changing bed substrates on salmonid spawning on large rivers. From this preliminary study, we argue that the approach could become a tractable and cost-effective tool for aquatic scientists to rapidly obtain bed texture maps without specialized knowledge of hydroacoustics. Bed texture maps can be used as a physical input for models relating ecosystem responses to hydrologic management.

Conference Paper↗
USGS2002

Use of an Acoustic Doppler Current Profiler (ADCP) to Measure Hypersaline Bidirectional Discharge

The U.S. Geological Survey measures the exchange of flow between the north and south parts of Great Salt Lake, Utah, as part of a monitoring program. Turbidity and bidirectional flow through the breach in the causeway that divides the lake into two parts makes it difficult to measure discharge with conventional streamflow techniques. An acoustic Doppler current profiler (ADCP) can be used to more accurately define the angles of flow and the location of the interface between the layers of flow. Because of the high salinity levels measured in Great Salt Lake (60-280 parts per thousand), special methods had to be developed to adjust ADCP-computed discharges for the increased speed of sound in hypersaline waters and for water entrained at the interface between flow layers.

Conference Paper↗
USGS1999

Life-history strategies of ungulates

This Special Feature resulted from a symposium on life-history strategies of ungulates presented at the 78th Annual Meeting of the American Society of Mammalogists in Blacks-burg, Virginia, in June 1998. The presentations at the symposium represented only a vignette of the wide variety of life-history strategies that exists among ungulates. The four papers that follow include treatises on birth-site selection of moose ( Alces alces ), sex-ratio correlates with dimorphism and risk of predation, optimal foraging relative to risk of predation, and the role of density dependence in shaping life-history traits of ungulates. A theme of risk of predation in shaping life-history traits is common to three of four papers.

Journal of Mammalogy↗
USGS2011

Digital surfaces and hydrogeologic data for the Floridan aquifer system in Florida and in parts of Georgia, Alabama, and South Carolina

A digital dataset for the Floridan aquifer system in Florida and in parts of Georgia, Alabama, and South Carolina was developed from selected reports published as part of the Regional Aquifer-System Analysis (RASA) Program of the U.S. Geological Survey (USGS) in the 1980s. These reports contain maps and data depicting the extent and elevation of both time-stratigraphic and hydrogeologic units of which the aquifer system is composed, as well as data on hydrology, meteorology, and aquifer properties. The three primary reports used for this dataset compilation were USGS Professional Paper 1403-B (Miller, 1986), Professional Paper 1403-C (Bush and Johnston, 1988), and USGS Open-File Report 88-86 (Miller, 1988). Paper maps from Professional Papers 1403-B and 1403-C were scanned and georeferenced to the North American Datum of 1927 (NAD27) using the Lambert Conformal Conic projection (standard parallels 33 and 45 degrees, central longitude -96 degrees, central latitude 39 degrees). Once georeferenced, tracing of pertinent line features contained in each image (for example, contours and faults) was facilitated by specialized software using algorithms that automated much of the process. Resulting digital line features were then processed using standard geographic information system (GIS) software to remove artifacts from the digitization process and to verify and update attribute tables. The digitization process for polygonal features (for example, outcrop areas and unit extents) was completed by hand using GIS software.

Alabama, Florida, Georgia, South Carolina↗
USGS1966

Magnitude and frequency of floods in the United States: Part 9. Colorado River Basin

This report outlines methods by which the magnitude and frequency of expected floods of any recurrence interval from 1.1 to 50 years can be determined at most points in the Colorado River basin. Composite frequency curves were drawn showing the relation of the mean annual flood to floods having recurrence intervals from 1.1 to 50 years. Other curves express the relation of the mean annual flood to basin characteristics. In the northern part of the basin (north of about lat 37° N.) both drainage area and mean altitude were important factors influencing the magnitude of the mean annual flood. Only drainage area was used as an independent variable in the southern part of the basin. By combining data from the composite frequency curves and curves showing the relation of the mean annual flood to basin characteristics, flood-frequency curves can be drawn for streams in the report area not materially affected by regulation or diversion within the range and recurrence interval defined by base data. Some of the larger streams in the basin do not lend themselves to regional analysis. These streams are given special treatment in this report. Owing to the paucity of streamflow data, flood-frequency relations are not defined in some of the more arid parts of the report area.

Arizona, California, Colorado, Nevada, Nevada, Uta↗
USGS1955

Photogeologic procedures in geologic interpretation and mapping

In the past few years increasing use has been made of aerial photographs for geologic interpretation and mapping within the U.S. Geological Survey. As a specialized technique in interpretation and mapping, however, photogeologic procedures were extensively used (1947-1953) in the Survey's geologic mapping of Naval Petroleum Reserve No. 4 in northern Alaska and in mapping part of the Colorado Plateau of western United States, principally in Utah (1951-present). Photogeologic work was performed by a specialized group of geologists that was organized as the Photogeology Section in June 1953. This group has more recently made studies of northeastern Utah, southern and southeastern Alaska, and central Alaska. Various photogeologic procedures have been used in these studies; some procedures have been modified, and new ones have been developed. It is primarily the purpose of this paper to discuss these procedures. Photogeologic procedures or techniques used outside the Geological Survey are not discussed herein.

Alaska, Utah↗
USGS1968

Late Eocene nonmarine diatoms from the Beaver Divide area, Fremont County, Wyoming

The Beaver Divide is a high escarpment of Tertiary nonmarine strata in central Wyoming separating the Sweetwater Plateau from the relatively low-lying Wind River Basin. The Wagon Bed Formation of middle and late Eocene age and the Beaver Divide Conglomerate Member of the White River Formation-this member being of early Oligocene (Chadronian) age--are exposed near the top of the Beaver Divide in Fremont County, Wyo., about 23 miles southeast of Riverton. The upper part of the Wagon Bed Formation, dated as late Eocene (Uintan) age by Van Houten on the basis of vertebrate fossils, contains a highly silicified fresh-water limestone stratigraphically high in the section with a poorly preserved diatom assemblage. The Beaver Divide Conglomerate Member contains large blocks of similar white limestone, some of which have an assemblage of diatoms the same as that of the Wagon Bed Formation but showing excellent preservation. Both the Wagon Bed limestone and the limestone blocks from the Beaver Divide Conglomerate Member have virtually the same assemblages of nonmarine gastropods. A study of the local geology indicates that a marked erosional topography formed on the Wagon Bed strata before deposition of the Beaver Divide sediments. The Beaver Divide limestone blocks were derived from nearby exposures of the Wagon Bed Formation. The diatom assemblage under consideration was originally deposited in the Wagon Bed limestone and is, therefore, late Eocene rather than early Oligocene in age. This represents the earliest known assemblage of nonmarine diatoms from North America. The diatom assemblage of the Wagon Bed Formation consists of 27 new species, two species known previously from the upper Miocene of France, and five species still found in living assemblages. One new genus containing two species also occurs in the deposit. The Wagon Bed diatom assemblage is strikingly distinct from later Tertiary fresh-water assemblages in that many diatom genera common to the younger deposits are totally lacking in this Eocene formation. These genera may be absent because of a highly specialized paleoecology during deposition of the Wagon Bed limestone, but the meager evidence provided by the few still-living species suggests nothing more specific than deposition in a temperate circumneutral lake.

Wyoming↗