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Research about Montana

Source-linked reports with geographic coverage including Montana.

At least 847 records · Page 47Linked to original sources
USGS1977

Major active faults and seismicity in and near the Big Fork-Avon area, Missoula-Kalispell region, northwestern Montana

This is one of a series of environmental maps of a study area that overlies parts of Flathead, Lake, Missoula, and Powell Counties, northwestern Montana. The area extends from Big Fork, in Lake County, on the north to Avon, in Powell County, on the south, essentially as outline in figure 1. The environmental study was undertaken by the U.S. Geological Survey in response to a request from the Regional Planning Association of Western Montana who believed that the data gathered would be of significant use to county land-use planner.s

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USGS1977

Paleomagnetic directions and poles of the early Eocene Lowland Creek volcanics and Eocene (?) volcanics of the Beaverhead Valley, western Montana

Virtual geomagnetic poles computed for (1) the Early Eocene Lowland Creek Volcanics near Butte, Montana, and (2) volcanic rocks of probable Eocene age from the Beaverhead Valley near Dillon, Montana, ace 72.2° N. lat., 4s. 165.2° W. long. and 76.7° N. lat., 159.3° W. long., respectively. These poles are in close agreement despite conspicuous dispersion of site mean directions of the Lowland Creek Volcanics.

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USGS1977

Ground-water resources in the Libby area, northwestern Montana

Glacial deposits and alluvium form the major aquifer in the Libby area. The glacial deposits are composed of Precambrian rocks that were broken and crushed, and then deposited as till by moving ice. The alluvium is composed of reworked glacial deposits that have been deposited by water, thereby sorting and increasing the permeability of the deposits. Ground water is generally available for domestic use throughout the Libby area. Wells tapping the glacial deposits commonly yield less than 30 gallons per minute. Wells tapping the alluvium often yield more than 500 gallons per minute; however, yields of less than 100 gallons per minute are more common. Water levels in wells tapping the glacial deposits and the alluvium along the Kootenai River and Libby Creek valleys respond rapidly to changes in stream stages. During the January 1974 flood, the water level in a well west of Libby rose 4 feet in 3 days. The chemical quality of the ground water is satisfactory for drinking. Dissolved-solids concentration of the water ranges from 32 to 370 milligrams per liter; the major constituents are calcium, magnesium, and bicarbonate. Areas where the nitrate (as N 3 O) concentration in ground water equals or exceeds 1.5 milligrams per liter are considered to be affected by septic-tank effluent.

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USGS1977

Natural radioactivity in geothermal waters, Alhambra Hot Springs and nearby areas, Jefferson County, Montana

Radioactive hot springs issue from a fault zone in crystalline rock of the Boulder batholith at Alhambra, Jefferson County, in southwestern Montana. The discharge contains high concentrations of radon, and the gross activity and the concentration of radium-226 exceed maximum levels recommended by the Environmental Protection Agency for drinking water. Part of the discharge is diverted for space heating, bathing, and domestic use. The radioactive thermal waters at measured temperatures of about 60°C are of the sodium bicarbonate type and saturated with respect to calcium carbonate. Radium-226 in the rock and on fractured surfaces or coprecipitated with calcium carbonate probably is the principal source of radon that is dissolved in the thermal water and discharged with other gases from some wells and springs. Local surface water and shallow ground water are of the calcium bicarbonate type and exhibit low background radio-activity. The temperature, percent sodium, and radioactivity of mixed waters adjacent to the fault zone increase with depth. Samples from most of the major hot springs in southwestern Montana have been analyzed for gross alpha and beta. The high level of radio-activity at Alhambra appears to be related to leaching of radioactive material from fractured siliceous veins by ascending thermal waters, and is not a normal characteristic of hot springs issuing from fractured crystalline rock in Montana.

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USGS1977

A summary of the mineral resources of the proposed Great Bear wilderness, Flathead, Teton, and Pondera counties, Montana

The proposed Great Bear wilderness has a good potential for oil and gas (mainly gas), and a moderate potential for submarginal resources of copper and silver in a belt 25 miles (40 km) long and about 1 mile (1.6 km) wide that is partly within the study area along the western boundary. The eastern part of the area may contain small submarginal resources of coal. Sand and gravel, dimension stone, and high calcium limestone are in the area, but they occur in abundance in more accessible areas elsewhere in northwest Montana. The potential for geothermal resources is nil. A mineral survey of the proposed Great Bear wilderness was made in 1974 and 1976. The work by the U.S. Geological Survey consisted of geologic mapping, and geochemical and geophysical surveys. The U.S. Bureau of Mines made a courthouse search for mining claims, and sampled and mapped prospects.

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