Skip to main content
U.S. flag

An official website of the United States government

Publications

Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center

Filter Total Items: 2495

Impact breccias in carbonate rocks, Sierra Madera, Texas 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...
Authors
H. G. Wilshire, Keith A. Howard, Terry W. Offield

Paleozoic metasediments in the northern Ruby Mountains, Nevada 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...
Authors
Keith A. Howard

Structural implications of an offset Early Cretaceous shoreline in northern California 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...
Authors
D. L. Jones, W. P. Irwin

Geologic map of Late Cenozoic deposits, Santa Clara County, California Geologic map of Late Cenozoic deposits, Santa Clara County, California

This map is the first of several in the San Francisco Bay region showing the distribution and differentiation of the late Cenozoic alluvial, estuarine, and volcanic deposits. The sedimentary deposits of gravel, sand, silt, and clay were separated into geologic map units on the basis of their post-depositional soil development, texture, and geomorphology. Some of the geologic units are...
Authors
E. J. Helley, E. E. Brabb
Was this page helpful?