Skip to main content
U.S. flag

An official website of the United States government

Publications

Filter Total Items: 2692

Structure and metamorphism of the Franciscan Complex, Mt. Hamilton area, Northern California

Truncation of metamorphic isograds and fold axes within coherent terranes of Franciscan metagraywacke by intervening zones of melange indicate that the melange is tectonic and formed after the subduction-related metamorphism and folding. These relations are expressed in two terranes of blueschist-facies rocks of the Franciscan Complex in the Mt. Hamilton area, northern California-the Jurassic Yoll
Authors
M. C. Blake, C. M. Wentworth

Foreshocks and aftershocks of the great 1857 California earthquake

The San Andreas fault is the longest fault in California and one of the longest strike-slip faults anywhere in the world, yet we know little about many aspects of its behavior before, during, and after large earthquakes. We conducted a study to locate and to estimate magnitudes for the largest foreshocks and aftershocks of the 1857 M 7.9 Fort Tejon earthquake on the central and southern segments o
Authors
A.J. Meltzner, D. J. Wald

How useful is landslide hazard information? Lessons learned in the San Francisco Bay region

Landslides, worldwide and in the United States, are arguably the most costly natural hazard. Substantial landslide information is available, but much of it remains underutilized, as a disconnect exists among geologists, decision makers, and the public. The lack of a national landslide insurance policy exacerbates this situation and promotes litigation as the principal recourse for recouping landsl
Authors
D. G. Howell, D.W. Ramsey, E. E. Brabb

Radionuclides in fly ash and bottom ash: Improved characterization based on radiography and low energy gamma-ray spectrometry

Two radiation-based techniques for determining the distribution and relative abundance of radionuclides are described, and applied to a suite of fly ash and bottom ash samples from a Kentucky power plant. The technique of fission-track radiography provides new observations of the variety of uranium hosts and of uranium distribution in individual particles of fly ash, and thus aids prediction of th
Authors
Robert A. Zielinski, James R. Budahn

A simplified economic filter for open-pit gold-silver mining in the United States

In resource assessments of undiscovered mineral deposits and in the early stages of exploration, including planning, a need for prefeasibility cost models exists. In exploration, these models to filter economic from uneconomic deposits help to focus on targets that can really benefit the exploration enterprise. In resource assessment, these models can be used to eliminate deposits that would proba
Authors
Donald A. Singer, W. David Menzie, Keith R. Long

Tertiary uplift of the Mt. Doonerak antiform, central Brooks Range, Alaska: Apatite fission track evidence from the Trans-Alaska crustal transect

The Mt. Doonerak antiform is a northeast-trending, doubly plunging antiform located along the axial part of the central Brooks Range. This antiform is a crustal-scale duplex estimated to have a vertical displacement of ~15 km. The antiform folds the Amawk thrust, which separates relatively less displaced lower plate rocks in a window in the core of the antiform from allochthonous upper plate rocks
Authors
P. B. O'Sullivan, Thomas E. Moore, J.M. Murphy

Digital geologic map of the Spokane 1:100,000 quadrangle, Washington and Idaho: A digital database for the 1990 N.L. Joseph map

Geologic data from the geologic map of the Spokane 1:100,000-scale quadrangle compiled by Joseph (1990) were entered into a geographic information system (GIS) as part of a larger effort to create regional digital geology for the Pacific Northwest. The map area is located in eastern Washington and extends across the state border into western Idaho (Fig. 1). This open-file report describes the meth
Authors
Bruce R. Johnson, Pamela D. Derkey

Field trip road log—geology and tectonics of the Gualala block

The Pacific Section, S.E.P.M. 1998 Fall Field Trip will traverse rocks of the Gualala block of northern California. Seven stops (Figure 1) will be made in one and a half days and will examine a variety of geologic features and rock types in this significant area. The field trip is an outgrowth of a symposium held at the 1998 Annual Meeting of the Pacific Section, S.E.P.M. in Ventura, California, w