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David G. Howell

If the San Andreas fault with about 300 km of right slip, the Carlock fault with about 60 km of left slip, and the Big Pine fault with about 15 km of left slip are considered to have been contemporaneously active, a space problem at their high-angle junctions becomes apparent. Large crustal masses converge in the area of the junctions as a result of the simultaneous large displacements on the faults. We present here a model in which an early straight north-northwest–trending San Andreas deforms to its present bent configuration in response to a westward displacement of crust north of the Garlock fault. During this deformation, the crust north of the Garlock in the vicinity of the junction undergoes north-south shortening,...
Categories: Publication; Types: Citation; Tags: Geology
The North America Tapestry of Time and Terrain (1:8,000,000 scale) is a product of the US Geological Survey in the I-map series (I-2781). This map was prepared in collaboration with the Geological Survey of Canada and the Mexican Consejo Recursos de Minerales. This cartographic Tapestry is woven from a geologic map and a shaded relief image. This digital combination reveals the geologic history of North America through the interrelation of rock type, topography and time. Regional surface processes as well as continent-scale tectonic events are exposed in the three dimensions of space and the fourth dimension, geologic time. The large map shows the varying age of bedrock underlying North America, while four smaller...
Categories: Publication; Types: Citation; Tags: IMAP
Alska is a complex amalgamation of tectonic blocks with diverse histories. Sedimentary basins that are formed on these blocks both before amalgamation and as a result of collisions between them record the tectonic history of this complex region. Thermal-maturity data-indicators of maximum burial temperatures-provide important constraints both on basin evolution and on terrane amalgamation. To help elucidate these relations, and to provide constraints for hydrocarbon assessments, the U.S. Geological survey (USGS) has compilied thermal-maturity data from Alaska for many decades. This report is a digital release of our current understanding of thermal-maturity patters in Alaska.
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 landslide-damage losses. The U.S. Geological Survey's landslide investigation in the San Francisco Bay region of California provides a context for making suggestions on how Earth science information could be used more effectively.
Categories: Publication; Types: Citation
No abstract available.
Categories: Publication; Types: Citation; Tags: Geotimes
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