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At least 541 records · Page 30Linked to original sources

Advancing geodesy in the U.S. Midcontinent: workshop report

The workshop on “Advancing Geodesy in the U.S. Midcontinent” was held from October 31 to November 1, 2012, at Northwestern University in Evanston, Illinois. The workshop included 28 participants from academia, government, and private-sector organizations that are involved in research on geodesy and earthquake hazards in the seismically active areas of the U.S. midcontinent (the region of relatively undeformed crust roughly between the Great Plains and Appalachian Mountains). The workshop was intended to provide guidance to the U.S. Geological Survey’s internal and external Earthquake Hazards research programs in the U.S. midcontinent. The 2012 workshop was developed as a follow-up to the “Workshop on New Madrid Geodesy and Understanding Intraplate Earthquakes,” held in Norwood, Massachusetts, in March 2011. The goal of the 2012 workshop was to provide specific recommendations to the U.S. Geological Survey on priorities for infrastructure and research investments related to geodesy in the U.S. midcontinent.

Open-File Report↗

Evaluation and correlation of water-quality data for the North Fork Flathead River, northwestern Montana

This report is a compilation and evaluation of water-quality measurements that have been made by the U.S. Geological Survey at two stations on the North Fork Flathead River in Montana. Historical streamflow records show an annual mean daily discharge of 3,010 cubic feet per second near the mouth--a threefold increase compared to discharge at the international boundary. The chemical character of the water is dominated by calcium and magnesium cations and the bicarbonate anion. Base flow, in contrast to high flows from runoff, is characterized by higher dissolved constituents and lower concentrations of suspended sediment. The several lakes that contribute water throughout the middle and lower drainage have a dampening effect on both streamflow and constituent concentrations. Using the available data and computer techniques, regression equations were developed between certain water-quality variables. (Woodard-USGS)

Water-Resources Investigations Report↗

Exploring the barriers for people taking protective actions during the 2012 and 2015 New Zealand shakeout drills

To reduce future earthquake injuries and casualties, it is important that people understand how their behavior, during and immediately following earthquake shaking, exposes them to increased risk of injury or death. Research confirms that protective actions can reduce injuries and that prior training can help prepare people to take appropriate actions. In this paper, we examine barriers to participation in the ShakeOut drills in New Zealand. Through citizen science research, volunteers observed people performing the drills in 2012 and 2015. Observers reported how long it took to perform the drill and why they thought some people may not have completed it. Our findings illustrate that children, elderly, and those with both mental and physical disabilities struggled with the drill. Furthermore, embarrassment was a reported leading cause for non-participation; we recommend more inclusive messaging to address potential causes of embarrassment.

International Journal of Disaster Risk Reduction↗

Strategic Plan for the North American Breeding Bird Survey, 2020–30

The North American Breeding Bird Survey (BBS) has been the cornerstone of continental bird conservation and management for hundreds of North American bird species in the United States and Canada for more than 50 years. This strategic plan was developed in collaboration with key partners and stakeholders and charts the ambitious course for the BBS over the next decade (2020–30). Using this plan as a guide, the BBS program will set out to improve the breadth and depth of standardized data collection and analytical products; ensure its products are widely used and recognized as the authoritative source for long-term population change information for most birds; and secure adequate resources, internally and through partnerships, to realize the expanded vision of the BBS intended to support avian management needs through 2030.

Circular↗

The Glacier National Park: A popular guide to its geology and scenery

The Glacier National Park includes that part of the Front Range of the Rocky Mountains lying just south of the Canadian line, in Teton and Flathead counties, Mont. It is bounded on the west by Flathead River (locally called North Fork), on the south by the Middle Fork of Flathead River and the Great Northern Railway, and on the east by the Blackfeet Indian Reservation. Although this part of the Rocky Mountains has been known since Lewis and Clark crossed the continent in 1805-6, the region later made a park appears not to have been visited by white men until 1853, when Cut Bank Pass was crossed by A. W. Tinkham, one of the Government engineers engaged in exploring a route for the Pacific railroad. Tinkham, who was encamped in the Bitterroot Valley, was ordered to examine Marias Pass, but in traversing Middle Fork of Flathead River along the line of the present railroad he was evidently misled by the large size of the valley of Nyack Creek and ascended that instead of keeping to the right up the main stream. He reported the pass impracticable for railroad construction, and so this region dropped out of public attention for a long time. The next explorers to enter the region were a group of surveyors who, under the direction of American and British commissioners, established the international boundary line along the forty-ninth parallel from the Pacific coast to the main summit of the Rocky Mountains. This party reached the area now included in the park in the summer of 1861, and the stone monument shown in Plate I, B, which they erected on the Continental Divide west of Waterton Lake, still marks a point on the boundary between the United States and Canada. The land on the west side of the range formed a part of the public domain which, until the erection of the park, was open to settlement, but the land on the east originally belonged to the Blackfeet Indians and the white men had no rights upon it. About 1890 copper ore was found near the heads of Quartz and Mineral creeks, and a great boom for this region followed. Many prospectors drifted in, expecting to reap rich rewards from the discovery of mineral deposits and the general development of the region. Several of the main trails were built about this time, and considerable money was spent in prospecting, in opening mines, and in providing machinery to handle the large output of copper ore that was expected. The copper-bearing veins were found to extend through the range to the east side, but prospecting in that part of the mountains was not possible, for the land was included in the Indian reservation. This situation produced a growing discontent among the prospectors, who began to have a strong feeling that the Government should come to their relief by acquiring the coveted land and placing it at their disposal. The urgent demand of the prospectors and promoters was felt in Congress, and a bill was passed providing for the purchase from the Indians of this supposed mineral land for $1,500,000. In accordance with this act, a treaty with the Blackfeet Indians was signed at Browning, Mont., September 26, 1895, and approved by the Senate on June 10, 1896, by which the west line of the reservation was removed from the Continental Divide and was fixed along the eastern points of the spurs of the mountain range, as shown on the accompanying map, and the land so acquired was thrown open to mineral entry only. Under the stimulus of the new territory acquired, active prospecting was carried on for a time, but copper ore was found only in small quantities, and gradually the prospectors and miners drifted away to newer or more promising fields, and the region reverted to its original condition. For a long time it was visited only by hunters in search of big game and by summer visitors who, in order to escape the heat of the plains, were willing to undergo the privations and discomforts of the rude hotels then to be found in the region. Although these mountains had ceased to interest prospectors in search of mineral wealth, they still possessed a fascination for the lovers of natural scenery and almost everyone who visited the region was impressed with its alpine beauty. Again it was brought to the attention of Congress, which was urged to secure it for the use of the people by setting it aside as a national park. On May 11, 1910, President Taft signed the bill creating the Glacier National Park, and this most interesting and beautiful region thus became a permanent playground for the American people.

Bulletin↗

Adaptation and response in drylands: A dryland research agenda and campaign strategy

Dryland ecosystems cover 41% of Earth's land surfaces, account for 44% of cultivated lands and 60% of food sources, and make large contributions to the global water and carbon cycles. However, these ecosystems are experiencing unprecedented extremes including heatwaves, floods, and droughts as well as hotter temperatures and often declining water resource availability. These ecosystems are some of the most challenging to monitor given their high temporal variability with rapid response to their environment as well as vast spatial variability with intermixing of different plant species and life forms amongst bare soil coverage. The Adaptation and Response in Drylands (ARID) campaign was selected by National Aeronautics and Space Administration (NASA) as a scoping study to develop a research agenda for a dryland field campaign. Here, we detail our ARID science research agenda and implementation plan that were developed based on an extensive community engagement effort in over 160 events with over a thousand scientists, land managers, and Tribal communities between 2023 and 2024. The selected science themes cover drought and climate variability, ecosystem structure, function, and biodiversity, carbon cycle interannual variability and trends, and social ecological systems (land management and adaptation). We then detail our remote sensing, modeling, and field-based strategies to capture high temporal and high spatial resolution processes. Finally, our implementation strategy is presented which includes focus area selections in a core intensive western U.S. domain and distributed international domains. This strategy includes our overarching guiding principles of using multi-temporal airborne acquisitions and super sites as well as enhancing land management in co-development with end-user partners. While originally developed for NASA, our ARID report creates a blueprint for any future dryland field campaign, at any scale, that can be implemented widely for foundational and applied science objectives.

Global Change Biology↗

Coeur d'Alene Lake, Idaho: Insights gained From limnological studies of 1991-92 and 2004-06

More than 100 years of mining and processing of metal-rich ores in northern Idaho’s Coeur d’Alene River basin have resulted in widespread metal contamination of the basin’s soil, sediment, water, and biota, including Coeur d’Alene Lake. Previous studies reported that about 85 percent of the bottom of Coeur d’Alene Lake is substantially enriched in antimony, arsenic, cadmium, copper, lead, mercury, silver, and zinc. Nutrients in the lake also are a major concern because they can change the lake’s trophic status—or level of biological productivity—which could result in secondary releases of metals from contaminated lakebed sediments. This report presents insights into the limnological functioning of Coeur d’Alene Lake based on information gathered during two large-scale limnological studies conducted during calendar years 1991–92 and water years 2004–06. Both limnological studies reported that longitudinal gradients exist from north to south for decreasing water column transparency, loss of dissolved oxygen, and increasing total phosphorus concentrations. Gradients also exist for total lead, total zinc, and hypolimnetic dissolved oxygen concentrations, ranging from high concentrations in the central part of the lake to lower concentrations at the northern and southern ends of the lake. In the southern end of the lake, seasonal anoxia serves as a mechanism to release dissolved constituents such as phosphorus, nitrogen, iron, and manganese from lakebed sediments and from detrital material within the water column. Nonparametric statistical hypothesis tests at a significance level of α=0.05 were used to compare analyte concentrations among stations, between lake zones, and between study periods. The highest dissolved oxygen concentrations were measured in winter in association with minimum water temperatures, and the lowest concentrations were measured in the Coeur d’Alene Lake hypolimnion during late summer or autumn as prolonged thermal stratification restricted mixing of the oxygenated upper water column and the hypolimnion, where oxygen was consumed. Large differences in median concentrations of dissolved inorganic nitrogen were measured between the euphotic zone and hypolimnion in the deep areas of the lake. These differences in nitrogen concentrations were attributable to several limnological processes, including seasonal inflow plume routing, isolation from wind-driven circulation and associated hypolimnetic enrichment, phytoplanktonic assimilation during summer months, and benthic flux. Increased chlorophyll- a and total phosphorus concentrations were measured throughout the lake in the 2004–06 study compared with results from the 1991–92 study. No significant change in hypolimnetic dissolved inorganic nitrogen concentration throughout the lake was noted even though total nitrogen loads into the lake decreased between study periods. Total zinc and total lead decreased throughout the lake from the 1991-92 study to the 2004-06 study except in the southern part of the lake, where concentrations were typically low. Median detected nitrogen-to-phosphorus ratios decreased from the 1991–92 study to the 2004–06 study. Whereas the lake was clearly phosphorus-limited in 1991–92, in 2004–06 the lake may have been much closer to the boundary value of 7.2 that separates nitrogen from phosphorus limitation. However, due to changes in analytical reporting limits in the period between the two studies, the data are insufficiently certain to draw reliable conclusions with regard to limiting nutrients. For both studies, the trophic state of the lake was classified as oligotrophic (less productive) or mesotrophic (moderately productive), depending on the constituent used for classification. Internal circulation from wind-generated waves and changes in the lake’s thermocline are important processes for distribution of water-quality constituents throughout Coeur d’Alene Lake. Surficial distribution of trace metals throughout most of the lake, including bays, is relatively uniform. Even south of the Coeur d’Alene River mouth, lakebed sediments are contaminated with trace metals. Inflow plume routing of the two primary inflow sources, the Coeur d’Alene and St. Joe Rivers, also significantly affects the fate and transport of contaminants. Most riverine inflows appear to move through the lake as overflow during summer, interflow during spring and autumn, and underflow during winter. Benthic flux is another key transport process for contaminants in Coeur d’Alene Lake. The results of in situ benthic flux chamber experiments indicated movement of dissolved metals, nutrients, and dissolved organic carbon out of the lakebed sediments. However, the lake is an overall sink for these constituents when they are associated with particulate material.

Idaho↗

Analytical assessments in support of the U.S. Fish and Wildlife Service 3-bat species status assessment

Beginning in February of 2020, researchers and staff of the United States Geological Survey (USGS), Bat Conservation International (BCI), Virginia Polytechnic Institute and State University, and Montana State University associated with the North American Bat Monitoring Program (NABat) collaborated with the United States Fish and Wildlife Service (USFWS) to provide technical assistance in support of the USFWS Three Bat Species Status Assessments (SSA) including the little brown bat (MYLU, Myotis lucifugus), northern long-eared bat (MYSE, Myotis septentrionalis), and tricolored bat (PESU, Perimyotis subflavus). Analytical support for the SSA was not intended to provide interpretive results, which should therefore be considered beyond the scope of this report. Technical assistance for the SSA included facilitating the USFWS data call by educating and working directly with data contributors to manage, submit, and archive a variety of bat monitoring data in the online NABat database1 using standardized data submission templates accessible through the upload features on the NABat website. Most data collected through the USFWS data call for the SSA were submitted and stored in the NABat database. These represent the efforts of hundreds of partnering organizations across more than 200 individual NABat Partner Portal Projects. A few organizations contributed data for use in these analyses that were not submitted to the NABat database. Records submitted in response to the USFWS data call included bat capture, stationary and mobile acoustic, and internal roost count data (winter and summer). Data collated in the NABat database and used for the analyses described herein are documented (NABat 2020a, NABat 2020b, NABat 2021) and available through the NABat third party request feature.

Report↗

Divisions of geologic time—Major chronostratigraphic and geochronologic units

Introduction Effective communication in the geosciences requires a consistent nomenclature for stratigraphic units and, especially, for divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and is calibrated in years. Geologists from the U.S. Geological Survey (USGS), State geological surveys, academia, and other organizations require a consistent time scale to be used in communicating ages of geo­logic units in the United States. Many international debates have occurred over names and boundaries of units, and various time scales have been used by the geoscience community. For consistent usage of time terms, the USGS Geologic Names Committee and the Association of American State Geologists devel­oped the Divisions of Geologic Time ; the 2018 update in this fact sheet contains the unit names and boundary age estimates ratified by the International Commission on Stratigraphy in 2018. Scientists may use other published time scales, provided that these are specified and referenced.

Fact Sheet↗

Hydrologic data for a study of pre-Illinoian glacial till in Linn County, Iowa, water year 1990

Hydrologic data for a study of pre-lllinoian glacial till were collected during the 1990 water year at a site in Linn County, Iowa. A hydrologic-data-collection network, consisting of 22 observation wells and a meteorological station, was installed at the site to describe the hydraulic properties of the till. Recorders were installed on 12 of the wells to continuously monitor water levels. Rainfall at the study site from April to October 1990, totaled 35.49 inches. The greatest monthly rainfall (13.15 inches) occurred in June. The greatest daily rainfall (6.00 inches) occurred on June 16. For the 16 wells less than 50 feet in depth, the highest water levels were recorded during the 4 months of greatest rainfall (May-August 1990). Water levels in the four deepest wens, completed in unconsolidated material, rose throughout the data-collection period. One well had water levels greater than the top of the well casing for most of the period from mid-May to mid-September 1990. A water-quality minimonitor was installed on one observation well near the top of the water table to monitor temporal changes in groundwater quality. For April through September 1990, the daily mean specific conductance ranged from 705 to 864 microsiemens per centimeter at 25 degrees Celsius, the daily mean water temperature ranged from 5.2 to 15.6 degrees Celsius, and the daily median pH remained nearly constant at 7.0 to 7.2 standard units. Ten unvented, vibrating-wire, pressure transducers with internal thermistors were buried in two boreholes at upgradient and downgradient locations to record hydraulic pressure arid water temperature at selected depths.

Iowa↗

GLORIA sidescan sonar field data and navigation data collected off Puerto Rico in 1985 and the eastern United States in 1987

This CD-ROM contains copies of the navigation and field sidescan sonar data collected within the Exclusive Economic Zone (EEZ) surrounding Puerto Rico and off the eastern United States during cruises aboard the R/V FARNELLA. The survey of the Puerto Rico EEZ was completed during one cruise between 4 November and 3 December, 1985. The survey of the EEZ off the eastern United States was completed during five cruises between 2 February and 30 May, 1987. The data were collected as part of the USGS EEZ-SCAN program which was a cooperative mapping program between the US Geological Survey and the Institute of Oceanographic Sciences of the UK. The survey areas included the entire US EEZ of Puerto Rico and the US Virgin Islands as well as of the eastern United States from the Canadian international boundary at Georges Bank to the Bahamian international boundary east of Florida. GLORIA imagery was collected seaward of approximately 400 m water depth.

Open-File Report↗

Stratigraphic inferences derived from borehole data of Tertiary basin-filling rocks of the Pahrump Valley basin, Nevada and California

This report summarizes the results from the compilation and interpretation of lithologic information from 266 driller?s logs from the Pahrump Valley, NV-CA. Borehole records for the Pahrump Valley were selected from a total of several thousand available well logs as those having lithologic data and high confidence in the well locations. Driller?s descriptions were reduced into one of 14 lithologic categories to produce a set of subsurface data that were internally consistent and amenable to contouring. Using the lithologic descriptors, the aggregate thickness of general lithologic types (coarse grained material, fine grained material, limestone, and volcanic material) were computed for each borehole. These data were used to compute ratios such as percent coarse-grained component of sedimentary rocks penetrated in each borehole that could be contoured.

Open-File Report↗

Water-quality and hydrogeologic data for three phosphate industry waste-disposal sites in central Florida, 1979-80

This report is a complilation of geologic, hydrologic, and water-quality data and information on test holes collected in the vicinity of gypsum stack complexes at two phosphate chemical plants and one phosphatic clayey waste disposal pond at a phosphate mine and beneficiation plant in central Florida. The data were collected from September 1979 to October 1980 at thee AMAX Phosphate, Inc., chemical plant, Piney Point; the USS AgriChemicals chemical plant, Bartow; and the International Minerals and Chemical Corporation Clear Springs mine, Bartow. Approximmmtely 5,400 field and laboratory water-quality determinations on water samples were collected from about 78 test holes and 31 surface-water, rainfall, and other sampling sites at phosphate industry beneficiation and chemical plant waste-disposal operations. Maps show locations of sampling sites. (USGS)

Florida↗

Degradation of trifluoroacetate in oxic and anoxic sediments

THE deleterious effect of chlorofluorocarbons on stratospheric ozone has led to international cooperation to end their use. The search for acceptable alternatives has focused on hydrofluorocarbons (HFCs) or hydrochlorofluorocarbons (HCFCs) which are attractive because they have relatively short atmospheric residence times. HFCs and HCFCs are attacked by tropospheric hydroxyl radicals, leading to the formation of trifluoroacetate (TFA). Most of the atmospheric TFA is deposited at the Earth's surface, where it is thought to be highly resistant to bacterial attack. Therefore, use of HCFCs and HFCs may lead to accumulation of TFA in soils, where it could prove toxic or inhibitory to plants and soil microbial communities. Although little is known about the toxicity of TFA, monofluoroacetate, which occurs at low levels in some plants and which is susceptible to slow attack by aerobic soil microbes, is known to be acutely toxic. Here we report that TFA can be rapidly degraded microbially under anoxic and oxic conditions. These results imply that significant microbial sinks exist in nature for the elimination of TFA from the environment. We also show that oxic degradation of TFA leads to the formation of fluoroform, a potential ozone-depleting compound with a much longer atmospheric lifetime than the parent compounds.The deleterious effect of chlorofluorcarbons on stratospheric ozone has led to international cooperation to end their use. The search for acceptable alternatives has focused on hydroflnorocarbons (HFCs) or hydrochloroflnorcarbons (HCFs) which are attractive because they have relatively short atmospheric residence times. HFCs and HCFs are attacked by tropospheric hydroxyl radicals, leading to the formation of trifluoroacetate (TFA). Most of the atmospheric TFA is deposited at the Earth's surface, where it is thought to be highly resistant to bacterial attack. Therefore, use of HCFs and HCFs may lead to accummulation of TFA in soils, where it could prove toxic or inhibitory to plants and soil microbial communities. Although little is known about the toxicity of TFA, monofluoracetate, which occurs at low levels in some plants and which is susceptible to slow attack by aerobic soil microbes, is known to be acutely toxic. Here we report that TFA can be rapidly degraded microbially under anoxic and oxic conditions. These results imply that significant microbial sinks exist in nature for the elimination of TFA from the environment. We also show that oxic degradation of TFA leads to the formation of fluoroform, a potential ozone-depleting compound with a much longer atmospheric lifetime than the parent compounds.

Nature↗

User guide for MODPATH version 6—A particle-tracking model for MODFLOW

MODPATH is a particle-tracking post-processing model that computes three-dimensional flow paths using output from groundwater flow simulations based on MODFLOW, the U.S. Geological Survey (USGS) finite-difference groundwater flow model. This report documents MODPATH version 6. Previous versions were documented in USGS Open-File Reports 89-381 and 94-464. The program uses a semianalytical particle-tracking scheme that allows an analytical expression of a particle's flow path to be obtained within each finite-difference grid cell. A particle's path is computed by tracking the particle from one cell to the next until it reaches a boundary, an internal sink/source, or satisfies another termination criterion. Data input to MODPATH consists of a combination of MODFLOW input data files, MODFLOW head and flow output files, and other input files specific to MODPATH. Output from MODPATH consists of several output files, including a number of particle coordinate output files intended to serve as input data for other programs that process, analyze, and display the results in various ways. MODPATH is written in FORTRAN and can be compiled by any FORTRAN compiler that fully supports FORTRAN-2003 or by most commercially available FORTRAN-95 compilers that support the major FORTRAN-2003 language extensions.

Techniques and Methods↗

Minerals, lands, and geology for the common defence and general welfare, Volume 4, 1939-1961: A history of geology in relation to the development of public-land, federal science, and mapping policies and the development of mineral resources in the United States from the 60th to the 82d year of the U.S. Geological Survey

The fourth volume of the comprehensive history of the U.S. Geological Survey (USGS) is titled “Minerals, Lands, and Geology for the Common Defence and General Welfare—Volume 4, 1939‒1961.” The title is based on a passage in the preamble of the U.S. Constitution. The late Mary C. Rabbitt (1915‒2002), a geophysicist who served with the U.S. Coast and Geodetic Survey (1948‒1949) and the USGS (1949‒1978), wrote the first three volumes in this series of USGS Special Books. “Volume 1, Before 1879” (1979), “Volume 2, 1879‒1904” (1980), and “Volume 3, 1904‒1939” (1986), although long out of print and out of stock, are now available online; see links at right. The 704-page Volume 4, supplemented by more than 200 illustrations, was begun by Rabbitt and completed by coauthor Clifford M. Nelson, a geologist with the USGS since 1976. The book is described as “A History of Geology in Relation to the Development of Public-Land, Federal Science, and Mapping Policies and the Development of Mineral Resources in the United States From the 60th to the 82d Year of the U.S. Geological Survey.” Volume 4 focuses on the United States and the USGS in war and peace from the beginning of World War II in Europe to the end of the administration of President Dwight D. Eisenhower. Like the earlier books in the series, Volume 4 places the nature and significance of USGS operations in mapping and the earth sciences in the wider contexts of national and international history. The new volume, like its three predecessors, is intended for general readers and historians alike, so it follows a chronological rather than a thematic pattern, although themes are traced throughout the book. After preparing Volumes 1–3, Rabbitt wrote a brief report summarizing the agency's history in its first century, “The United States Geological Survey: 1879‒1989,” which was originally issued as USGS Circular 1050 in 1989. It was reissued in 2000 as part of USGS Circular 1179, which also contains Renée M. Jaussaud’s inventory of documents accessioned through 1997 into Record Group 57 (USGS) at the National Archives and Records Administration’s Archives II facility (NARA II) in College Park, Maryland.

Book↗

Gazetteer of planetary nomenclature 1994

Planetary nomenclature, like terrestrial nomenclature, is used to uniquely identify a feature on the surface of a planet or satellite so that the feature can be easily located, described, and discussed. This volume contains detailed information about all names of topographic and albedo features on planets and satellites (and some planetary ring and ring-gap systems) that the International Astronomical Union has named and approved from its founding in 1919 through its triennial meeting in 1994. This edition of the Gazetteer of Planetary Nomenclature supersedes an earlier informal volume distributed by the U.S. Geological Survey in 1986 as Open-File Report 84-692 (Masursky and others, 1986). Named features are depicted on maps of the Moon published first by the U.S. Defense Mapping Agency or the Aeronautical Chart and Information Center and more recently by the U.S. Geological Survey; on maps of Mercury, Venus, Mars, and the satellites of Jupiter, Saturn, and Uranus published by the U.S. Geological Survey; and on maps of the Moon, Venus, and Mars produced by the U.S.S.R. Although we have attempted to check the accuracy of all data in this volume, we realize that some errors will remain in a work of this size. Readers noting errors or omissions are urged to communicate them to the U.S. Geological Survey, Branch of Astrogeology, Rm. 409, 2255 N. Gemini Drive, Flagstaff, AZ 86001.

Bulletin↗