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Wilfred James Carr

Publications and source records attributed to Wilfred James Carr.

At least 19 recordsLinked to original sources
USGS1975

Geology, physical properties, and surface effects at Discus Thrower Site, Yucca Flat, Nevada test site

Geologic studies in connection with Project Discus Thrower have furnished detailed stratigraphic and structural information about northwestern Yucca Flat. The Paleozoic rocks consist of a lower carbonate sequence, argillite of the Eleana Formation, and an upper carbonate sequence. The distribution of these rocks suggests that both top and bottom of the Eleana are structural contacts, probably thrusts or reverse faults. The overlying tuff includes several units recognized in the subsurface, such as the Fraction Tuff and tuff of Redrock Valley. Other units recognized include bedded tuff associated with the Grouse Canyon Member of Belted Range Tuff, and the Rainier Mesa and Ammonia Tanks Members of the Timber Mountain Tuff. The Timber Mountain and Grouse Canyon are extensively altered to montmorillonite (a swelling clay), possibly as a result of ponding of alkaline water. The overlying alluvium locally contains at the base a clayey, tuffaceous sandstone. Geophysical logs were used as an aid in locating geologic contacts and determining in situ physical properties. Graphic logs are presented that show the correlation of lithology and geophysical logs. Many of the rock units have characteristic log responses, but alteration within rock units affects the logs strikingly in some drill holes. The most significant surface effect of the experiment was the formation of a 4-foot fault scarp northwest of the site.

Open-File Report↗
USGS1974

Summary of tectonic and structural evidence for stress orientation at the Nevada Test Site

A tectonic synthesis of the NTS (Nevada Test Site) region, when combined with seismic data and a few stress and strain measurements, suggests a tentative model for stress orientation. This model proposes that the NTS is undergoing extension in a N. 50 ? W.-S. 50 ? E. direction coincident with the minimum principal stress direction. The model is supported by (1) a tectonic similarity between a belt of NTS Quaternary faulting and part of the Nevada-California seismic belt, for which northwest-southeast extension has been suggested; (2) historic northeast- trending natural- and explosion-produced fractures in the NTS; (3) the virtual absence in the NTS of northwest-trending Quaternary faults; (4) the character of north-trending faults and basin configuration in the Yucca Flat area, which suggest a component of right-lateral displacement and post-10 m.y. (million year) oblique separation of the sides of the north-trending depression; (5) seismic evidence suggesting a north- to northwest-trending tension axis; (6) strain measurements, which indicate episodes of northwest-southeast extension within a net northeast-southwest compression; (7) a stress estimate based on tectonic cracking that indicates near-surface northwest-southeast-directed tension, and two stress measurements indicating an excess (tectonic) maximum principal compressive stress in a northeast-southwest direction at depths of about 1,000 feet (305 m); and (8) enlargement of some drill holes in Yucca Flat in a northwest-southeast direction. It is inferred that the stress episode resulting in the formation of deep alluvium-filled trenches began somewhere between 10 and possibly less than 4 m.y. ago in the NTS and is currently active. In the Walker Lane of western Nevada, crystallization of plutons associated with Miocene volcanism may have increased the competency and thickness of the crust and its ability to propagate stress, thereby modulating the frequency (spacing) of basin-range faults.

Open-File Report↗
USGS1961

Late quaternary history of the snake river in the American Falls region, Idaho

While mapping the American Falls region, we found evidence that contributes to the middle Pleistocene to Recent history of the Snake River, and indirectly to the history of overflow of Lake Bonneville. Middle Pleistocene to recent rocks in the valley are mainly lacustrine and fluvial silts and clays, with some sand, gravel, basalt, and a few thin tuff beds. The formation of terraces can be correlated with events both up- and downstream. The Snake River was at least once, and possibly twice, dammed and diverted by eruptions of basalt, resulting in the formation of lakes and deposition of lacustrine beds. A rather flat-lying, thin, but persistent gravel at the base of one lake bed formation may represent a glacial period, possibly Illinoian, during which the Snake River had a large volume. Overflow of water from Lake Bonneville into the Snake River system, by way of the Marsh Creek-Portneuf valley, laid down a deltaic-fluvial deposit here named the Michaud Gravel. At this time the Snake River, greatly augmented by Lake Bonneville overflow, began to cut channels through and around a lava dam. Terraces between Aberdeen, American Falls, and Pocatello were formed during the existence of the lake in which the Michaud Gravel was deposited and by fluvial processes after drainage of the lake. At one stage in the downcutting, bars of huge basalt boulders were built across the mouths of abandoned spillways. Radiocarbon dating and geologic evidence from the area between Preston and Soda Springs, Idaho, suggest that basalt flows diverted the Bear River into Lake Bonneville, perhaps causing it to overflow. This diversion probably occurred about 33,000 years ago. This dating accords with events in the American Falls region.

Idaho↗