Publications
Filter Total Items: 2692
Structure of Sierra Madera, Texas, as a guide to central peaks of lunar craters
Like hundreds of other lunar craters of probable impact origin, Copernicus contains central peaks presumed to expose rocks uplifted from beneath the crater floor. A possible analog of these peaks on Earth is the central uplift of the Sierra Madera cryptoexplosion structure, a probable impact scar (astrobleme) in stratified Permian and Cretaceous rocks of west Texas. The most conspicuous part of th
Authors
Keith A. Howard, Terry W. Offield, H. G. Wilshire
Geologic setting of the Apollo 15 samples
The samples and photographs returned from the Apollo 15 site show that Hadley Delta is largely underlain by breccias whose clasts are mainly fragments of coarse-grained feldspathic rocks and nonmare-type basalt. Conspicuous sets of lineaments, visible in surface and orbital photographs of Mount Hadley and Hadley Delta, may represent systematic layering or fracture sets. The mare surface, with rego
Authors
G.A. Swann, N. G. Bailey, R. M. Batson, V. L. Freeman, M. H. Hait, H. E. Holt, K.B. Larson, V. S. Reed, G. G. Schaber, R. L. Sutton, E.W. Wolfe, Keith A. Howard, H. G. Wilshire, J.W. Head, J.B. Irwin, D.R. Scott, W.R. Muehlberger, L. T. Silver, J. J. Rennilson
Paleomagnetic correlations and Potassium-Argon dating of Middle Tertiary ash-flow sheets in the eastern Great Basin, Nevada and Utah
Directions of natural remanent magnetization are used to identify and correlate individual cooling units in the middle Tertiary ash-flow province in central and eastern Nevada and western Utah. Potassium-argon dating indicates that the minimum time between eruptions of individual but genetically related ash-flow cooling units is on the order of 0.8 m.y. As this interval is long in comparison with
Authors
C. S. Grommé, E. H. McKee, M. Clark Blake
Paleomagnetism and potassium-argon ages of the Sonoma Volcanics, California
Paleomagnetic data and potassium-argon ages indicate that the Sonoma Volcanics was erupted during the Pliocene Gilbert reversed and Gauss normal polarity epochs. The Gilbert reversed epoch is represented in the Howell Mountains east of Napa and east of St. Helena, in the mountains immediately east of the Valley of the Moon, and on the hill just north of Santa Rosa. The Gauss normal epoch is repres
Authors
Edward A. Mankinen
Principal facts for gravity stations in the San Francisco district and adjoining areas, Utah
Observed gravity values, station locations, terrain corrections, and Bouguer gravity data are provided in tabular form for approximately 450 gravity observations in southwestern Utah.
Authors
Donald L. Peterson
Geological Survey research 1972, Chapter C
This collection of 37 short papers is the second published chapter of "Geological Survey Research 1972." The papers report on scientific and economic results of current work by members of the Conservation, Geologic, and Water Resources Divisions of the U.S. Geological Survey.Chapter A, to be published later in the year, will present a summary of significant results of work done ~n fiscal year 1972
Authors
Paleozoic metasediments in the northern Ruby Mountains, Nevada
New evidence indicates that high-grade regionally metamorphosed marble and quartzite in the northern Ruby Mountains are Paleozoic strata. Correlation is based on a match of the lithologic sequence to strata of Cambrian to Devonian age in nearby areas; particularly diagnostic is a brown dolomite at the base of the Cambrian carbonate sequence. The metamorphic complex contrasts with unmetamorphosed
Authors
Keith A. Howard
Impact breccias in carbonate rocks, Sierra Madera, Texas
Two main types of deformational breccia occur in the Sierra Madera cryptoexplosion structure: monolithologic breccias composed of shattered rock of a single lithology and mixed breccias composed of rocks of several lithologies. Monolithologic breccias generally show no mineralogic signs of shock deformation, but a few samples are shatter-coned in a manner suggesting simultaneous formation of brecc
Authors
H. G. Wilshire, Keith A. Howard, Terry W. Offield
Structural implications of an offset Early Cretaceous shoreline in northern California
Recognition of a nonmarine to marine transition in sedimentary rocks at Glade Creek and Big Bar in the southern Klamath Mountains permits reconstruction of the approximate position of a north-trending Early Cretaceous (Valanginian) shoreline. At the southern end of the Klamath Mountains, the shoreline is displaced 60 mi or more to the east by a west-northwest-trending fault zone. South of this fau
Authors
D. L. Jones, W. P. Irwin
The earthquake sequence near Danville, California, 1970
Several thousand small earthquakes, with magnitudes ranging up to 4, occurred near Danville, California, during May, June, and July 1970. Seven temporary seismographs were installed near the epicentral region to augment an existing telemetered network within 1 day after the first felt earthquake. The dense concentration of 10 seismographs within 12 km of the seismic activity and the existence of a
Authors
W.H.K. Lee, M.S. Eaton, E. E. Brabb