This CD-ROM contains images generated from geophysical data, software for displaying and analyzing the images and software for displaying and examining profile data from aerial surveys flown as part of the National Uranium Resource Evaluation (NURE) Program of the U.S. Department of Energy. The images included are of gamma-ray data (uranium, thorium, and potassium channels), Bouguer gravity data, isostatic residual gravity data, aeromagnetic anomalies, topography, and topography with bathymetry. This publication contains image data for the conterminous United States and profile data for the conterminous United States within the area longitude 108 to 126 degrees W. and latitude 34 to 49 degrees N. The profile data include apparent surface concentrations of potassium, uranium, and thorium, the residual magnetic field, and the height above the ground. The images on this CD-ROM include graytone and color images of each data set, color shaded-relief images of the potential-field and topographic data, and color composite images of the gamma-ray data. The image display and analysis software can register images with geographic and geologic overlays. The profile display software permits the user to view the profiles as well as obtain data listings and export ASCII versions of data for selected flight lines.

Data Series↗

USGS1993

Understanding our fragile environment; Lessons from geochemical studies

An understanding of our fragile environment can begin with a recognition of the importance of certain elements, commonly called "minerals substances" (such as iron and zinc), in the lives of humans and animals and in the soils that support plants. This recognition is well deserved because these elements are essential for the life or optimum health of an organism. Some elements such as carbon, hydrogen, oxygen, magnesium, potassium, and phosphorus are required in relatively large amounts by organisms. However, others are required in smaller quantities; these are referred to as trace elements. Diseases have been related to the deficiency of about 20 elements in animals and humans and to the deficiency of approximately 13 elements in plants. At the same time, if these and other elements occur in quantities great enough, toxicity can result. An element, or any substance, that occurs in the environment and contains concentrations above what are considered to be background levels may be considered a contaminant. When contaminants occur at levels that are potentially harmful to organisms, they are labeled as hazards. Often the quantitative difference between essential amounts and toxic concentrations of these elements is very small. For example, the trace element selenium is required at a level of no less than 0.4 ppm in the diet of cattle but can be toxic at levels greater than approximately 4ppm. Elements that are required for survival by animals and plants are termed essential, while those not required are nonessential. Trace essential elements such as fluorine, copper, selenium, molybdenum, and others listed in the table on page 1 can be hazardous to life forms if present at high levels. Nonessential heavy metals such as arsenic, lead, mercury, cadmium, and chromium are usually toxic to organisms at much lower levels than trace essential elements. Depending on the association that these nonessential elements may form with natural geologic materials such as organic matter, other elements or minerals, and adsorbers (such as clays), these elements can range from being safe to being extremely toxic. The elemental composition of plants, animals, and humans correlates with the geologic makeup of the Earth, and life has evolved reflecting these natural occurrences. The science of environmental geochemistry examines the interrelationship of life with the physical and chemical Earth.

Circular↗

USGS1993

National geophysical data grids; gamma-ray, gravity, magnetic, and topographic data for the conterminous United States

Overview and installation Note: the information on this site was copied from an optical medium publication. Although all data and software published on this CD-ROM have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials. This CD-ROM has been produced in accordance with the ISO 9660 CD- ROM Standard and is therefore capable of being read on any computing platform that has appropriate CD-ROM driver software installed. However, the access software used on the disc currently executes only under DOS on IBM or compatible personal computers. OVERVIEW This CD-ROM contains gridded geophysical data, images generated from the data, software for displaying and analyzing the images, software for processing potential-field (gravity and magnetic) geophysical data, and documentation files that describe the data and software. The gridded data include gamma-ray data (uranium, thorium, and potassium channels), Bouguer gravity data, isostatic residual gravity data, aeromagnetic anomalies, topography, and topography with bathymetry. These data are available in ASCII format under the ASCII directory. This publication contains only data from the conterminous United States. The images on this CD-ROM include graytone and color images of each gridded data set, color shaded-relief images of the potential-field and topographic data, color composite images of the gamma-ray data, and color composite images of potential-field data painted on shaded and edge-enhanced topography. These images are 8-bit data and can be imported for viewing by many different software packages, but the color display tables are only designed for DOS computers and displays. The display and analysis software includes the ability to register images with geographic and geologic overlays, generate three-color composite images for display on a super VGA video system, generate perspective view images, and analyze images in five dimensions. The potential-field software on this CD-ROM can be used to extract subsets of the geophysical data, process them, and display them as images or contour maps. The software can also be used to generate gridded data from point data, generate profiles from grids, and generate geological models from gridded or profile data. This software is written in FORTRAN and, with minor modifications, can be adapted to a variety of computer systems. The documentation files reside under the directory DOSMENU\DOCFILES and are named with a suffix of DOC. This directory also contains a WordPerfect 5.1 file (CDROM.WPS) that contains all of the documentation. This CD-ROM is released in the Digital Data Series of CD-ROM's produced by the U.S. Geological Survey. This new publication series is intended to improve distribution of important earth science information to the public. The disc contains the results of work performed by the U.S. Geological Survey. INSTALLATION If you have not already done so, run the INSTALL program by making the CD-ROM drive the active drive and typing INSTALL followed by pressing the key. Follow the instructions printed on the screen. When the INSTALL program is finished, it will invoke the national geophysics (NATGP) menu program, and you will see a menu of your options. If you have previously run the INSTALL program and you have added C:\ to the PATH statement in your AUTOEXEC.BAT file, run the menu program directly by typing NATGP followed by pressing the key. If C:\ is not in your search path, you will have to type C:\NATGP followed by pressing the key. A menu of your options will appear on the screen.

Data Series↗

USGS1990

Modern aerial gamma-ray spectrometry and regional potassium map of the conterminous United States

Aerial gamma-ray surveys of the natural environment measure the flux of gamma rays produced by the radioactive decay of 40 K, 214 Bi, and 208 Tl in the upper 10–20 cm of surface materials. 40 K is a radioactive potassium isotope which can be used to estimate the total amount of potassium in the soils and rocks. 214 Bi is a decay product of the 238 U radioactive decay series and is used to estimate the uranium concentrations, and 208 Tl, a decay product of the 232 Th radioactive decay series, is used to estimate thorium concentrations. Aerial gamma-ray data covering the 48 contiguous states of the United States have been compiled to produce maps showing the distributions of equivalent uranium, equivalent thorium, and potassium. This compilation involved processing the aerial survey data from about 470 1° × 2° quadrangle maps. The aerial gamma-ray data were obtained as part of the National Uranium Resource Evaluation (NURE) Program sponsored by the U.S. Department of Energy during the period 1975-1983. References for the Open-File Reports that describe the surveys and data collection can be found in Bendix Field Engineering Corp. (1983). The aerial surveys were flown by contractors using fixed-wing and helicopter systems with 33-50 L (liters) of thallium-activated sodium iodide (NaI (TI)) crystals. The nominal survey altitude used is 122 m. The survey lines were generally east-west with line spacings of 1.6-10 km. Tie lines were flown perpendicular to the flight lines at intervals of 16- 30 km. The data were corrected for background from aircraft contamination and cosmic rays, altitude variations, airborne 214Bi, and Compton scattering. The gamma-ray systems were calibrated using the calibrations pads at Grand Junction, Colorado (Ward, 1978 ) and the dynamic test strip at Lake Mead, Arizona (Geodata International, Inc., 1977).

Journal of Geochemical Exploration↗

USGS1990