Geology of the Cordelia and the northern part of the Benicia 7.5 minute quadrangles, California: A digital map database

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Frequently anticipated questions:


What does this data set describe?

Title:
Geology of the Cordelia and the northern part of the Benicia 7.5 minute quadrangles, California: A digital map database
Abstract:
This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (cdbegeo.txt or cdbegeo.ps), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller.
Supplemental_Information:
Database includes:

ARC/INFO export file  Description of coverage
cd_sp-py.e00          Faults, depositional contacts, and rock units in the Cordelia 7.5 minute quadrangle
cd_sp-sr.e00          Strike and dip information and fold axes in the Cordelia 7.5 minute quadrangle
be_sp-py.e00          Faults, depositional contacts, and rock units in the northern part of the Benicia 7.5 minute quadrangle
be_sp-sr.e00          Strike and dip information and fold axes in the northern part of the Benicia 7.5 minute quadrangle
cd_sp-flt.e00         Index map of faults in the Cordelia 7.5 minute quadrangle with annotation showing the names of major faults
be_sp-flt.e00         Index map of faults in the northern part of the Benicia 7.5 minute quadrangle with annotation showing the names of major faults
cdbe_corr.e00         Correlation table for the units in this map database.  This database is not geospatial
cdbe_so.e00           Sources of data index map for this map database.  Arcs only.
cdbe_as.e00           Index map of Assemblages in the Cordelia and the northern part of the Benicia 7.5 minute quadrangles.
cdxs_sp-ln.e00        Map showing location of cross-sections.  Arcs only.
cdxsa.e00             Cross-section A.  This database is not geospatial.
cdxsb.e00             Cross-section B.  This database is not geospatial.

Other files           Description
cdbegeo.ps            A PostScript plot file of a report containing detailed unit descriptions and geological information, plus sources of data and references cited.
cdbegeo.pdf           A PDF version of cdbegeo.ps
cdbegeo.txt           A text-only file containing an unformatted version of cdbegeo.ps
cdbedb.ps             A PostScript plot file containing information on the database files.
cdbedb.pdf            A PDF version of cdbedb.ps.
cdbedb.txt            A text-only file containing an unformatted version of cdbedb.ps
import.aml            ASCII text file in ARC Macro Language to convert ARC export files to ARC coverages in ARC/INFO.
cdbekey.txt           Together, these three ASCII text files contain the information given in the description of map units and symbols on the map sheet (cdbemap.ps or cdbemap.pdf)
cdbekey2.txt
cdbekeysym.txt
cdbeso.txt            ASCII text file containig information about sources of data as shown in the sources of data index map (cdbe_so) described above.
  1. How might this data set be cited?
    Graymer, R.W., Brabb, E.E., and Jones, D.L., 1999, Geology of the Cordelia and the northern part of the Benicia 7.5 minute quadrangles, California: A digital map database: U.S. Geological Survey Open-File Report 99-162.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.25
    East_Bounding_Coordinate: -122.13
    North_Bounding_Coordinate: 38.25
    South_Bounding_Coordinate: 38.04
  3. What does it look like?
    http://pubs.usgs.gov/of/1999/of99-162/cdbemapl.pdf (PDF)
    PDF representation of lower portion of the geologic map sheet.
    http://pubs.usgs.gov/of/1999/of99-162/cdbemapu.pdf (PDF)
    PDF representation of upper portion of geologic map sheet.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1999
    Currentness_Reference:
    Date given is publication date of the digital map database
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: map
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Entity point
      • complete chain
      • GT-polygon composed of chains
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: California State Plane Coordinate system
      State_Plane_Coordinate_System:
      SPCS_Zone_Identifier: 3326
      Planar coordinates are encoded using coordinate pair
      Planar coordinates are specified in meters
  7. How does the data set describe geographic features?
    CD_SP-PY.PAT and BE_SP-PY.PAT
    Geologic map units of Cordelia and the northern part of the Benicia quadrangles, California (? indicates uncertainty in mapped unit) (Source: OFR-99-162)
    PTYPE
    Polygon type (Source: OFR-99-162)
    ValueDefinition
    afArtificial fill (Historic)
    alfArtificial levee fill (Historic)
    QhascArtificial stream channels (Historic)
    QhscStream channel deposits (Holocene)
    QhbmBay mud (Holocene)
    QhafAlluvial fan and fluvial deposits (Holocene)
    QclColluvium (Holocene)
    QlsLandslide deposits (Pleistocene and/or Holocene)
    QpafAlluvial fan and fluvial deposits (Pleistocene)
    QpoafOlder alluvial fan deposits (Pleistocene)
    TsvSonoma Volcanics, undivided (Pliocene and Miocene?)
    TssVolcanic mudstone, sandstone, and conglomerate: Sonoma Volcanics, undivided (Pliocene and Miocene?)
    TcCierbo Sandstone (Miocene)
    TvUnnamed volcanics (Miocene?)
    TmkMarkley Formation (Eocene)
    TmkjJameson Mudstone member: Markley Formation (Eocene)
    TnvNortonville Shale (Eocene)
    TdDomingene Sandstone (Eocene)
    TmrMuir Sandstone of Weaver (1953) (Eocene)
    TljLas Juntas Shale of Weaver (1953) (Paleocene and Eocene)
    TvhVine Hill Sandstone of Weaver (1953) (Paleocene)
    KuUndivided sandstone and shale (Early and Late Cretaceous)
    KJkKnoxville Formation (Late Jurassic and Early Cretaceous)
    JsvSilicic volcanic rocks (Late Jurassic)
    JbBasalt: Coast Range Ophiolite (Jurassic)
    JgbGabbro: Coast Range Ophiolite (Jurassic)
    spSerpentinite: Coast Range Ophiolite (Jurassic)
    KJfmFranciscan melange: Franciscan Complex (Cretaceous and Jurassic)
    lsAlgal limestone (age unknown)
    H2Owater
    BE_SP-FLT.AAT and CD_SP-FLT.AAT
    Faults in the Cordelia and the northern part of the Benicia quadrangles, California (Source: OFR-99-162)
    LTYPE
    Line type (Source: OFR-99-162)
    ValueDefinition
    fault, approx. locatedFault whose position is not precisely known.
    fault, certainFault whose position is certain.
    fault, concealedFault that is concealed and its position inferred.
    reverse fault, approx. locatedReverse fault whose positions is not presicesly known.
    reverse fault, certainReverse fault whose position was observed.
    reverse fault, concealedReverse fault that is concealed and its position inferred.
    thrust fault, approx. locatedThrust fault whose position is not precisely known.
    thrust fault, certainThrust fault that was observed.
    thrust fault, inferredThrust fault whose position is inferred.
    BE_SP-PY.AAT and CD_SP-PY.AAT
    Linear features on map including contacts, boundaries, and faults. (Source: OFR-99-162)
    LTYPE
    Line Type (Source: OFR-99-162)
    ValueDefinition
    contact, approx. locatedContact whose position is not precisely known.
    contact, certainContact that was observed.
    contact, inferredContact whose position is inferred.
    fault, approx. locatedFault whose position is not precisely known.
    fault, certainObserved fault.
    fault, concealedFault that is concealed and its position inferred.
    map boundaryBoundary of mapped quadrangle
    reverse fault, approx. locatedReverse fault whose position is not precisely known.
    reverse fault, certainObserved reverse fault
    reverse fault, concealedReverse fault whose position is concealed and inferred.
    thrust fault, approx. locatedThrust fault whose position is not precisely known.
    thrust fault, certainObserved thrust fault.
    thrust fault, inferredThrust fault whose position is inferred.
    water boundaryBoundary of a body of water.
    BE_SP-SR.AAT and CD_SP-SR.AAT
    Fold axes in the Benicia and Cordelia 7.5 minute quadrangle (Source: OFR-99-162)
    LTYPE
    Line type (Source: OFR-99-162)
    ValueDefinition
    f.a., anticline, approx. locatedAnticline whose position is not precise.
    f.a. anticline, certainObserved anticline
    f.a., anticline, concealedAnticline that is concealed and position inferred.
    f.a., syncline, approx. locatedSyncline whose position is not precise.
    f.a. syncline, certainObserved syncline
    f.a., syncline, concealedSyncline that is concealed and its position inferred.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • R.W. Graymer
    • E.E. Brabb
    • D.L. Jones
  2. Who also contributed to the data set?
    We are grateful to the following U.S. Geological Survey paleontologists who have examined our fossils and provided ages necessary to establish the stratigraphic sequence and structure: David Bukry (Cretaceous and Tertiary nannoplankton), Kristin McDougall (Tertiary foraminifers), William Sliter (deceased - Cretaceous and Eocene foraminifers), John Barron (Tertiary diatoms), Charles Powell II (Tertiary mollusks), and Bonita Murchey (Mesozoic radiolaria).
    We are also very grateful to managers and staff of Chevron, EXXON, UNOCAL, ARCO, and Shell Petroleum Companies who have provided reports, maps, picked slides, and residues for about 25,000 microfossil localities in the San Francisco Bay Region.
    Carl Wentworth kindly provided advice on digitizing and editing procedures. Ed Helley provided materials and advice on Quaternary units.
  3. To whom should users address questions about the data?
    R.W. Graymer
    US Geological Survey
    1345 Middlefield Rd., MS 975
    Menlo Park, CA
    USA


Why was the data set created?

To provide current information on the geologic structure and stratigraphy of a geologic map of the Cordelia and the northern part of the Benicia 7.5' quadrangles, California.

How was the data set created?

  1. From what previous works were the data drawn?
    Graymer, Jones, and Brabb (1994) (source 1 of 1)
    Graymer, R.W., Jones, D.L., and Brabb, E.E., 1994, Preliminary geologic map emphasizing bedrock formations in Contra Costa County, California: A digital database: U.S. Geological Survey Open-File Report OFR-94-622.

    Type_of_Source_Media: online
    Source_Contribution: Created the litholigic associates in the area
  2. How were the data generated, processed, and modified?
    (process 1 of 2)
    Digital compilation
    The geologic map information was digitized from stable originals of the geologic maps at 1:24,000 scale. The author manuscripts (pencil on mylar) were scanned using a Altek monochrome scanner with a resolution of 800 dots per inch. The scanned images were vectorized and transformed from scanner coordinates to projection coordinates with digital tics placed by hand at quadrangle corners. The scanned lines were edited interactively by hand using ALACARTE, color boundaries were tagged as appropriate, and scanning artifacts visible at 1:24,000 were removed.
    Base maps
    Base Map layers were prepared from Digital Raster Graphic (DRG) versions of standard U.S. Geological Survey 7.5 minute quadrangles obtained from the U.S. Geological Survey Mapping Division Website for the San Francisco Bay region (http://bard.wr.usgs.gov). Please see the website for more detailed information about the original DRGs. The DRGs were converted to ARC/INFO GRIDs using the imagegrid command. The GRIDS were then edited by us to remove area fill colors (for example urban pink and purple, forested green, and water blue). The edited GRIDs were then combined with GRIDs produced from the geologic map coverages and overlain with vector data to produce the final cartographic product presented in cdbeplt.ps and cdbeplt.pdf. Because the base map digital files (DRGs) are already available at the website mentioned above, they are not included in the digital database package.
    Date: 24-Jul-2000 (process 2 of 2)
    Creation of original metadata record Person who carried out this activity:
    Jennifer Lenz
    US Geological Survey
    12201 Surise Valley Drive, Mail Stop 918
    Reston, VA
    USA

    703-648-6974 (voice)
    703-648-6560 (FAX)
    pschweitzer@usgs.gov
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Complete
  5. How consistent are the relationships among the observations, including topology?
    This map database represents the integration of previously published and unpublished maps by several workers and new geologic mapping and field checking by the authors.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints: none
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey Information Services
    Box 25248, Denver Federal Center
    Denver, CO
    USA

  2. What's the catalog number I need to order this data set? USGS Open-File report 99-162
  3. What legal disclaimers am I supposed to read?
    This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
    This database, identified as "Geology of the Cordelia and the northern part of the Benicia 7.5 minute quadrangles, California: A digital map database," has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 05-Feb-2016
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse, http://geo-nsdi.er.usgs.gov/
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA
USA

703-648-6533 (voice)
703-648-6252 (FAX)
pschweitzer@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://geo-nsdi.er.usgs.gov/metadata/open-file/99-162/metadata.faq.html>
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