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.
Preliminary quaternary geologic maps of Santa Clara Valley, Santa Clara, Alameda, and San Mateo counties, California: A digital database
This digital map database, which is compiled from previouslyunpublished and open-filed U.S. Geol. Survey reports (Wesling andHelley, 1989), represents the general distribution and identity ofQuaternary deposits in eight 7.5 minute quadrangles in the southernSan Francisco Bay region, California.
San Francisco Bay Region landslide folio part E - Map of debris-flow source areas in the San Francisco Bay region, California
This map identifies the principal areas in the San Francisco Bayregion that are likely to produce debris flows, which are alsocalled "mudslides." Debris flows that occur in the bay region arefast-moving downslope flows of mud that may include rocks,vegetation, and other debris. These flows begin during intenserainfall as shallow landslides on steep slopes. The rapid movementand sudden arrival of debris flows pose a hazard to life andproperty during and immediately following the triggering rainfall.Debris flows in a given storm originate from a number of sourcesscattered throughout steep parts of the landscape, as shown infigure 1 (on map sheet; files sfbr- df.ps, al-df.ps, etc.). Duringsubsequent storms, new debris...
General distribution of geologic materials in the southern San Francisco Bay region, California: A digital map database
The ssfb_m1 digital map database, which is compiled from 1970'svintage sources, represents the general distribution and identityof geologic materials in the southern San Francisco Bay region,California, west of the Calaveras fault. It is not a geologic map,because it does not address the geologic structure or thestratigraphic organization of the map units in a systematic way.Instead, it is directed at the distribution and character of thegeologic materials following the pattern of its progenitors,Wentworth and others (1985) and Ellen and Wentworth (in press).Consultation of these reports and the other compilation sources willaid in using the database.
This Open-File report is a digital physiographic map database.This physiographic map of the Grand Canyon is modified fromprevious versions by Billingsley and Hendricks (1989), andBillingsley and others (1997). The boundary is drawn approximatelyalong the topographic rim of the Grand Canyon and its tributarycanyons between Lees Ferry and Lake Mead (shown in red). Severalisolated small mesas, buttes, and plateaus are within this area,which overall encompasses about 2,600 square miles.The Grand Canyon lies within the southwestern part of the Colorado Plateaus of northern Arizona between Lees Ferry, Colorado River Mile 0, and Lake Mead, Colorado River Mile 277. Limestone rocks of the Kaibab Formation form most of the...
Preliminary geologic map emphasizing bedrock formations in Alameda County, California: A digital database
This Open-File report is a digital geologic map database of the Alameda County, California.
The area of this data set includes the classic geology and mineral deposits of the Keweenaw Peninsula, renowned for the occurrence of great volumes of Middle Proterozoic flood basalts and the world's largest concentration of native copper. Native copper was mined there continuously from the 1840's to the 1960's. For the earlier part of that period the Keweenawan native copper district was the principal source of copper for the United States.
The Little Piute Mountains in the eastern Mojave Desert expose a seriesof folds and thrust faults involving metamorphosed Paleozoic strata (Millerand others, 1982; Stone and others, 1983). The Little Piute Mountains Digital database contains digital geologic and geographic information for the study area. The geology was mapped at a scale of 1:8,000, and the topographic information was input from the Little Piute Mountains, CA 1:24,000 quadrangle.
The data in this CD-ROM are based on a mineral resource assessment of the Venezuelan Guayana Shield, conducted between 1987 and 1991 by the U.S. Geological Survey and Corporaci�n Venezolana de Guayana, T�cnica Minera, (USGS, 1993). The Venezuelan Shield occupies about 415,000 sq km in the south and east part of Venezuela. The study area is bounded on the north by the R�o Orinoco. It includes all of the Territorio Federal Amazonas, Estado Bol�var, and part of Estado Delta Amacuro. The original resource assessment publication USGS Bulletin 2062 consists of 121 pages of text and figures as well as eight full-color maps:GeographicGeologic and tectonicBouguer gravityTwo mineral-occurrence mapsSide-looking airborne radar...
Geologic map of the Hayward fault zone, Contra Costa, Alameda, and Santa Clara Counties, California: A digital database
This digital map database, compiled from previously open- filed U.S.Geological Survey reports (Graymer and others, 1994, Graymer,Jones, and Brabb, 1994) and unpublished data, represents thegeneral distribution of rocks and faults in the Hayward fault zone.As described in this report, the Hayward fault zone is a zone ofhighly deformed rocks which trends north 30 degrees west from anarea southeast of San Jose to the San Pablo Bay, and ranges inwidth from 2 to 10 kilometers. Although historic earthquakeactivity has been concentrated in the western part of the zone, thezone as a whole reflects oblique right-lateral and compressivedeformation along a significant upper crustal break over the past10 million years or more....
Preliminary geologic map emphasizing bedrock formations in Contra Costa County, California: A digital database
This digital map database, which is compiled from previouslypublished and unpublished sources combined with new mapping,represents the general distribution and identity of bedrock in ContraCosta County, California.