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

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At least 397 records · Page 22Linked to original sources
USGS1967

Preliminary report on Bureau of Mines Yellow Creek core hole No. 1, Rio Blanco County, Colorado

Analysis of geologic, hydrologic , and geophysical data obtained in and around Yellow Creek core hole No. 1, Rio Blanco County, Colorado, indicate a 1,615-foot section of oil shale was penetrated by the hole. Geophysical log data indicate the presence of 25 gallons per ton shale for a thickness of 500 feet my be marginal. The richest section of oil shale is indicated to be centered around a depth of 2,260 feet. Within the oil shale the interval 1,182 to 1,737 feet is indicated to be relatively structurally incompetent and probably permeable. Extension of available regional hydrologic data indicate the oil shale section is probably water bearing and may yield as much as 1,000 gallons per minute. Hydrologic testing in the hole is recommended.

Open-File Report↗
USGS1967

Phosphate rock in Colombia - a preliminary report, with a section on the phosphate occurrence at Turmeque

Exploration for phosphate rock in Colombia was successfully carried out in 3 1/2 months by the U.S. Geological Survey and the Inventorio Minero of the Servicio Geologico Nacional, under the auspices of the U.S. Agency for International Development. A modern theory of exploration based on model studies of phosphorite deposits is that phosphate is deposited in the miogeosyncline adjacent to the foreland or craton, where parts of the ocean are deep, where deposition of clastic material is at a minimum, and where upwelling currents deposit a suite of rocks characterized by chert, black shale, carbonate rock, and phosphorite. Although phosphate is found in rocks of all geologic periods, economic deposits are known only in certain of: the periods--one of these being the Late Cretaceous. As previous work had demonstrated that phosphate is present in Colombia only in rocks of Cretaceous age, and is most abundant in rocks of Late Cretaceous age--the La Luna Formations and Guadalupe--in the Cordillera Oriental, work was accordingly confined to the Cordillera Oriental and to rocks of Late Cretaceous age. Particular emphasis was paid to facies changes in the miogeosyncline; the field investigation pointed to the area in Norte de Santander where the best phosphorite was found. Phosphate deposits were found in both the geosynclinal and the platform facies in Upper Cretaceous rocks spread through a large area of the Cordillera Oriental, from Huila in the south to Norte de Santander in the north, a distance of more than 600 kilometers.

Open-File Report↗
USGS1970

Digital computer terrain mapping from multispectral data, and evaluation of proposed Earth Resources Technology Satellite (ERTS) data channels, Yellowstone National Park preliminary report

Digital computer processing of 12 wavelength bands of visible and reflective infrared scanner data has resulted in successful automatic computer mapping of eight terrain units in a Yellowstone National Park test site. Target areas in the scene were selected for training the computer. Statistical parameters of radiance such as mean, standard deviation, divergence, and covariance were computed for each category of material. These data were used in the computer program to determine which channels are most useful for recognition of all object categories studied, and to actually classify all the unknown data points into the known categories. The following terrain types have been mapped with greater than 80 percent accuracy in a 12-square-mile area with 1,800 feet of relief: bedrock exposures, talus, vegetated rock rubble, glacial kame terrace, glacial till, forest, bog, and water, and shadows. In addition, shadows of clouds and cliffs are depicted. In addition, studies were made of the effectiveness of the proposed Earth Resources Technology Satellite (ERTS) data channels as compared to the computer-selected best four channels in the automatic recognition and mapping of the same terrain types based on simulations, using the same set of data. These simulations resulted in maps whose accuracies were only a few percent less than that using the best set of four channels; they indicate that the ERTS data channels are likely to be successful for terrain analysis of a wide variety of categories encompassing a broad range of spectral reflectance. These studies also indicate that, for a broad range of terrain categories, many' combinations of 3 or 11 channels of data would be satisfactory. We need worry about careful selection of specific wavelength bands only if there is a specific category being sought.

Idaho, Montana, Wyoming↗
USGS1971

Preliminary report on the geology and field petrology at the Apollo 15 landing site

The Apollo 15 mission was a landmark in the manned geologic exploration of the Moon. The geologic diversity and significance of the site, the extended traverse capability provided by three EVAs and the Lunar Roving Vehicle, the real time television coverage of the terrain and crew activities, and, most of all, the magnificent performance of the astronaut crew contributed to an unprecedentedly successful mission.

Open-File Report↗
USGS1971

Cretaceous plutonic rocks of St. Lawrence Island, Alaska; a preliminary report

Reconnaissance mapping on St. Lawrence Island, Alaska has revealed seven epizonal granitic plutons of mid-Cretaceous age with a combined outcrop area of about 350 square miles. The plutonic rocks are dominantly quartz monzonite, but include minor amounts of granodiorite, monzonite, syenite, syenodiorite, and alaskite. The plutons are structurally and petrologically similar to and about the same age as plutons on the Chukotsky Peninsula, U.S.S.R. and in western Alaska. They suggest tectonic continuity between Siberia and Alaska since at least Cretaceous time. Several mineralized areas containing molybdenum, copper, lead, and zinc sulfides are associated with the plutonic bodies in the western part of the island.

Alaska↗
USGS1972

Geology of Hadley Rille preliminary report

Hadley Rille generally trends in directions that are controlled by pre-mare structures. The southern half of the rille, south of the Apollo 15 site, follows a mare-filled graben that is concentric to the Imbrium basin; however, the zigs and zags in the course are mainly north and east-northeast, directions that do not reflect pre-mare structures in adjacent highlands. The northern half of the rille follows a general direction that is parallel to pre-mare Imbrium-radial faults, is less sinuous than farther south, and intersects several fault-like features, all of which suggest some structural control along this part of the course. At the Apollo 15 site, the east rim is 30-40 m higher than the west rim as if the rille were a normal fault. The rille cannot be a simple fault, however, because the two sides do not match; instead, at bends, the outside has less curvature than the inside, which is partly attributed to recession of the rims by mass-wasting.

Open-File Report↗