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This digital map database, compiled from previously publishedand unpublished data, and new mapping by the authors,represents the general distribution of bedrock and surficialdeposits in the mapped area. Together with the accompanyingtext file (nesfmf.ps, nesfmf.pdf, nesfmf.txt), it providescurrent information on the geologic structure and stratigraphyof the area covered. The database delineates map units thatare identified by general age and lithology following thestratigraphic nomenclature of the U.S. Geological Survey. Thescale of the source maps limits the spatial resolution (scale)of the database to 1:62,500 or smaller.
Tags: 06013 = Contra Costa, 06041 = Marin, 06055 = Napa, 06067 = Sacramento, 06077 = San Joaquin, All tags...
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These maps show, for emergency service managers in the San FranciscoBay region, the threshold rainfall that may be capable oftriggering a level of debris-flow activity likely to threatenpublic safety. The maps are products of a continuing series ofstudies that began after a catastrophic storm on January 3-5, 1982triggered 18,000 debris flows in the San Francisco Bay region,causing 25 deaths and $66 million in property damage. Thethreshold rainfall values were estimated by re-evaluating aprevious empirical analysis of data from the 1982 storm, and otherhistorical rainfall records, that normalized the rainfall intensitydata by dividing by the mean annual precipitation (MAP) of thecorresponding rain gage. The present...
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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...
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Contra Costa County is located at the northern end of the DiabloRange of Central California. It is bounded on the north byCarquinez Strait, through which flows 27 percent of California'ssurface water runoff. San Francisco Bay forms the westernboundary, the San Joaquin Valley borders it on the east and theLivermore Valley forms the southern boundary. Contra Costa is oneof the nine Bay Area counties with streams that are tributaries toSan Francisco Bay. Most of the county is mountainous with steeprugged topography. Mount Diablo, in the center of the county, isone of the highest peaks in the Bay Area, reaching an elevation of1173 meters (3,849 ft). Contra Costa County is covered bytwenty-five 7.5' topographic Quadrangles...
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.
A table keyed to 171 topographic quadrangles on a new1:275,000-scale shaded-relief map speeds access to information onlandslide locations in the ten-county San Francisco Bay region.Detailed maps showing individual landslides in nearly any area ofinterest can be found quickly by knowing only the name of theappropriate 7.5' quadrangle. The some-80 technical reports thatcontain these maps may be consulted in the U.S. Geological Survey'sMenlo Park library collection.
The distribution of landslides evident in the landscape -- most ofwhich are slumps, translational slides, and earth flows -- is ofinterest both for evaluation of hazard and risk and for use infurther study of landslides. Future movement of such landslides ismost likely to occur within and around the places where they havepreviously occurred. A map showing the generalized distribution ofthese landslides was published by Nilsen and Wright for the 9-countySan Francisco Bay region in 1979. Original sources available at thetime of that compilation were incomplete for the region. Landslidemapping that has since become available provides a basis forrevision and extension of that work, and modern procedures allowthis to...
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This report presents a preliminary map and database ofQuaternary deposits and liquefaction susceptibility for thenine-county San Francisco Bay region, together with a digitalcompendium of ground effects associated with past earthquakesin the region. The report consists of (1) a spatial database offivedata layers (Quaternary deposits, quadrangle index, andthree ground effects layers) and two text layers (a labels andleaders layer for Quaternary deposits and for groundeffects), (2) two small-scale colored maps (Quaternary depositsand liquefaction susceptibility), (3) a text describing theQuaternary map, liquefaction interpretation, and the groundeffects compendium, and (4) the databse description pamphlet.The nine...
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This Open-File report consists of a digital geologic map database and associated digital plot files and text files, revised from a hard copy by Sowers and others (1995). This digital map database provides current information on Quaternary geology and liquefaction susceptibility of the Napa, California, 1:100,000 quadrangle. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey.
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This digital map database, compiled from previously published andunpublished data, and new mapping by the authors, represents thegeneral distribution of bedrock and surficial deposits in the mapped area.Together with the accompanying text file (mageo.txt, mageo.pdf, ormageo.ps), it provides current information on the geologic structure andstratigraphy of the area covered. The database delineates map units thatare identified by general age and lithology following the stratigraphicnomenclature of the U.S. Geological Survey. The scale of the source mapslimits the spatial resolution (scale) of the database to 1:62,500 orsmaller.
    map background search result map search result map Digital geologic map and map database of parts of Marin, SanFrancisco, Alameda, Contra Costa, and Sonoma Counties, California Geologic map and map database of northeastern San Francisco Bay region, California; Most of Solano County and parts of Napa, Marin, Contra Costa, San Joaquin, Sacramento, Yolo, and Sonoma Counties Preliminary maps of Quaternary deposits and liquefactionsusceptibility, nine-county San Francisco Bay region,California: a digital database A digital version of the 1970 US Geological Survey topographic map of the San Francisco Bay region, three sheets, 1:125,000 Quaternary geology of Contra Costa County, and surrounding parts of Alameda, Marin, Sonoma, Solano, Sacramento, and San Joaquin Counties, California: A digital database Quaternary geology and liquefaction susceptibility, Napa, California 1:100,000 quadrangle: A digital database Digital geologic map and map database of parts of Marin, SanFrancisco, Alameda, Contra Costa, and Sonoma Counties, California Quaternary geology of Contra Costa County, and surrounding parts of Alameda, Marin, Sonoma, Solano, Sacramento, and San Joaquin Counties, California: A digital database Quaternary geology and liquefaction susceptibility, Napa, California 1:100,000 quadrangle: A digital database Geologic map and map database of northeastern San Francisco Bay region, California; Most of Solano County and parts of Napa, Marin, Contra Costa, San Joaquin, Sacramento, Yolo, and Sonoma Counties A digital version of the 1970 US Geological Survey topographic map of the San Francisco Bay region, three sheets, 1:125,000 Preliminary maps of Quaternary deposits and liquefactionsusceptibility, nine-county San Francisco Bay region,California: a digital database