Preliminary Surficial Geologic Map Database of the Amboy 30x60 Minute Quadrangle, California

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Frequently-anticipated questions:

What does this data set describe?
    Title:
    Preliminary Surficial Geologic Map Database of the Amboy 30x60 Minute Quadrangle, California
    Abstract:
    The surficial geologic map database of the Amboy 30x60 minute quadrangle presents characteristics and physical properties of surficial materials for an area approximately 5,000 km2 in the eastern Mojave Desert of California at a scale of 1:100,000. This map consists of new surficial mapping conducted between 2000 and 2005 in the area, as well as compilations of previous bedrock mapping simplified to emphasize lithologic source material. Surficial geology units are mapped and described based on depositional process and age categories that reflect the mode of deposition, pedogenic effects occurring post-deposition, and, where appropriate, the lithologic nature of the material. The physical properties recorded in the database focus on those that drive hydrologic, biologic, and physical processes such as particle size distribution (PSD) and bulk density. This version of the database is distributed with point data, representing locations of both laboratory determined physical properties and semi-quantitative field-based information. Future publications will include the complete field and lab data, as well as maps of distributed physical properties across the landscape tied to physical process models where appropriate. The database is distributed in 3 parts: spatial map-based data, documentation, and printable map graphics of the database. Spatial data is distributed as an Arc/Info coverage in ESRI interchange (e00) format, or as tabular data in the form of a DBF-file (DBF) file. Documentation includes this file, which provides a discussion of the surficial geology and describes the format and content of the map data. The documentation also includes FGDC metadata for the spatial map information. Map graphics files are distributed as Postscript and Adobe Portable Document Format (PDF) files, and are appropriate for representing a view of the spatial database at the mapped scale.

  1. How should this data set be cited?

    U.S. Geological Survey, Unknown, Preliminary Surficial Geologic Map Database of the Amboy 30x60 Minute Quadrangle, California: Open-File Report 2006-1165.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -116.0
    East_Bounding_Coordinate: -115.0
    North_Bounding_Coordinate: 35.0
    South_Bounding_Coordinate: 34.5

  3. What does it look like?

    amboy_browse.jpg (JPEG)
    Small browse graphic of the Amboy 1:100,000 scale quadrangle

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2006
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  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):

      • Complete chain (9972)
      • Label point (3805)
      • GT-polygon composed of chains (3805)
      • Point (4)

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 11
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -117.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000860
      Ordinates (y-coordinates) are specified to the nearest 0.000860
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    amb-geo.aat
    Arc attributes for coverage 'amb_geo' (Faults, depositional contacts, and rock units) (Source: This Report)

    FID
    Internal feature number. (Source: ESRI)

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    FNODE#
    Internal node number for the beginning of an arc (from-node). (Source: ESRI)

    Whole numbers that are automatically generated.

    TNODE#
    Internal node number for the end of an arc (to-node). (Source: ESRI)

    Whole numbers that are automatically generated.

    LPOLY#
    Internal node number for the left polygon. (Source: ESRI)

    Whole numbers that are automatically generated.

    RPOLY#
    Internal node number for the right polygon. (Source: ESRI)

    Whole numbers that are automatically generated.

    LENGTH
    Length of feature in internal units. (Source: ESRI)

    Positive real numbers that are automatically generated.

    AMB-GEO#
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    AMB-GEO-ID
    User-defined feature number. (Source: ESRI)

    LTYPE
    Geologic Line types (e.g. contact, fault) (Source: This Report)

    ValueDefinition
    contact, approximately locatedBoundary between two mapped units that has been observed but the location is not precise
    contact, certainBoundary between two mapped units that was observed, the location of which is well known
    contact, eolian gradationalBoundary between two mapped units that is transitional in properties between the mapped units through eolian processes, the location of which is approximate and may vary with in the direction of eolian transport
    contact, gradationalBoundary between two mapped units that is transitional over an area.
    fault, approximately locatedStructural boundary between mapped units or structural discontinuity within a mapped unit that has experienced relative offset. Locational accuracy is approximate,
    fault, certainStructural boundary between mapped units or structural discontinuity within a mapped unit that has experienced relative offset. Locational accuracy is well located
    fault, concealedStructural boundary between mapped units or structural discontinuity within a mapped unit that has experienced relative offset. The fault is obscured by overlying map units, so it is not well-located
    fault, concealed, queriedStructural boundary between mapped units or structural discontinuity within a mapped unit that has experienced relative offset. The fault is obscured by overlying map units, so it is not well-located
    fault, queriedStructural boundary between mapped units or structural discontinuity within a mapped unit that has experienced relative offset. The fault is obscured by overlying map units or has not been visited in the field, so its existence and location is not well-known
    map boundaryEdge of mapped area, used to bound polygons at the edge of the map database.

    amb-geo.pat
    Polygon attributes for coverage 'amb_geo' (Faults, depositional contacts, and rock units) (Source: This Report)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    AREA
    Area of feature in internal units squared. (Source: ESRI)

    Positive real numbers that are automatically generated.

    PERIMETER
    Perimeter of feature in internal units. (Source: ESRI)

    Positive real numbers that are automatically generated.

    AMB-GEO#
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    AMB-GEO-ID
    User-defined feature number. (Source: ESRI)

    PTYPE
    Geologic polygon (map unit) designation (Source: This report)

    Unique values of this field are presented in the associated text

    amb_field.dbf
    Locations, map unit types, and nature of other observations for the map area (Source: This report, map units may represent those found in Bedford, 2003, and others (see map text))

    UTM_E
    UTM (NAD83 Zone 11N) easting (X) coordinate (Source: This report)

    UTM_N
    UTM (NAD83 Zone 11N) northing(Y) coordinate (Source: This report)

    Date
    Date of observation (Source: This report)

    StationID
    Text of the Author's station identification corresponding to notes (Source: This Report)

    Last_Name
    The last name of the Authors making the observation (Source: This report)

    map_unit
    The Author's free-form map unit (i.e. ptype in the geologic map) which may not correspond to exact map units in the 1:100,000 scale map classification (Source: This report)

    BD_Moist
    Boolean (Y or N) for presence or absence of a Bulk Density/Field Moisture determination (Source: This Report)

    Chronology
    Boolean (Y or N) for presence or absence of a geochronology sample (Source: This report)

    Lithology
    Boolean (Y or N) for presence or absence of a parent lithology determination(s) (Source: This report)

    PSA
    Boolean (Y or N) for presence or absence of a particle size analysis (texture) sample (Source: This report)

    Photos
    Boolean (Y or N) for presence or absence of digital photograph(s) (Source: This report)

    Surface_desc
    Boolean (Y or N) for presence or absence of surface description (e.g. clast size, lichen, eolian processes) (Source: This Report)

    Vegetation
    Boolean (Y or N) for presence or absence of vegetation measurements (Source: This report)

    Entity_and_Attribute_Overview:
    Geologic polygon (map unit) types are stored in the Ptype field of the polgyon layer for coverage amb_geo Geologic line types (e.g. contact, fault) are stored in the Ltype field of the arc layer for coverage amb_geo
    Entity_and_Attribute_Detail_Citation: This report

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    David R. Bedford
    U.S. Geological Survey
    Geologist
    345 Middlefield Rd MS973
    Menlo Park, CA 94025
    USA

    650-329-4924 (voice)
    650-329-4936 (FAX)
    dbedford@usgs.gov

Why was the data set created?
Describe the surficial materials in the mapped area

How was the data set created?
  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?

    map units, contacts, or faults are attributed with an appended '?' if their designation is assumed and not definite.

  2. How accurate are the geographic locations?

    Accuracy of line locations is carried in the database and displayed by different line symbols (solid vs. dashed lines) in the cartographic display. For the purpose of this database, solid lines represent contacts and faults located with an accuracy greater than 10 m and commonly greater than 5 m. Dashed lines represent two kinds of less certainly located features, each distinguished in the database: 1) contacts and faults located with an accuracy of 10 to 15 m, 2) contacts that represent gradational boundaries between adjacent units. Gradational contacts represent interleaving of sediments and smooth gradations in characteristics such as percentage of eolian sand. In general, these gradations take place over distances of 50 to 150 m.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Complete for publication standards

  5. How consistent are the relationships among the observations, including topology?

    Geologic lines attributed as a 'contact' do not separate geologic map units of the same type, and are not considered as 'dangles'. All geologic polygons are attributed with map unit designators found in the Description of Map Units

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:
Acknowledgement of the U.S. Geological Survey; uses of this digital geologic map should not violate the spatial resolution of the data. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data.

  1. Who distributes the data set? (Distributor 1 of 1)

    U. S. Geological Survey
    c/o USGS Information Services
    Box 25286 Denver Federal Center
    Denver, CO 80225-0046
    USA

    1-888-ASK-USGS (voice)
    infoservices@usgs.gov

  2. What's the catalog number I need to order this data set?

    This Open-File Report consists of three digital packages. The first is the Documentation Package, which consists of this file in text and Adobe Portable Document Format (PDF), a Portable Document Format (PDF) file of the geologic map and an accompanying geologic pamphlet (which includes a more detailed description of map units), FGDC metadata for the Report, and possibly a revision list. The second is Digital Database Package, which contains the geologic map database itself, and metadata. The third is the Plot file Package, which contains an on-screen viewable or printable image of the geologic map created from the database in PostScript and PDF formats. For those interested in the geology of the map area that do not use an ARC/INFO-compatible (Environmental Systems Research Institute, www.esri.com) Geographic Information System (GIS), we have provided two sets of plot files containing images of much of the information in the database. There is a plot file image in Adobe Acrobat PDF (<http://www.adobe.com/>) format (see Plot file Package sections below). Those who have computer capability can access the plot file packages in any of the three ways described below (see the section Obtaining the Digital Database and Plot file Packages). However, the plot file packages do require zip utilities to access the plot files. Therefore, additional software, available free on the Internet, may be required to use the plot files (see Zip files section). Those without computer capability can obtain plots from an outside vendor (see section Obtaining plots from an outside vendor). Note: filenames used in this report are based on combinations of the Open-File Report number, followed by an underscore, followed by the number of the package, followed by an alphabetic character denoting the part of that package, followed by a ".", and a three or four digit file extension. For example, for a text file of the metadata part of the documentation package (package number 1) in Open-File Report OF99_999 (a fictitious report number) would have a file name of of099_999_1a.txt Documentation Package The Documentation Package includes descriptions of this report, including instructions on how to get the report, data formats and content. It consists of 3 parts, a text description (this file), FGDC compliant metadata describing the report, and a revision list that lists any revisions made to this report. The documentation package contains the following: of06-1165_1a.txt a text file of the report text (this file) of06-1165_1a.pdf a PDF file of the report text (this file) of06-1165_1b.txt a text file of the geologic description pamphlet of06-1165_1b.pdf a PDF file of the geologic description pamphlet of06-1165_1c.txt a text file of FGDC compliant metadata for this report of06-1165_1d.html a HTML file of FGDC compliant metadata for this report of06-1165_1e.html a HTML 'FAQ' file of FGDC compliant metadata for this report Digital Database Package The database package includes geologic map database files for the map area. The digital maps, or coverages, along with their associated database directory have been converted to uncompressed ARC/INFO export files for distribution. ARC export files promote ease of data handling, and are usable by some Geographic Information Systems in addition to ARC/INFO (see below for a discussion of working with export files). Additionally, ARC export files are files that contain both the spatial and associated database information, so that it is possible to read and interpret the files and write simple code to convert the files to a format more convenient to the user, should no such code be available off-the-shelf. The ARC export files and associated ARC/INFO coverages, and directories, as well as the additional digital material included in the database, are described below: of06-1165_2a.e00 Faults, depositional contacts, and rock units in the quadrangle of06-1165_2b.dbf A DBF table of field observations The database package (of05-1165_3.zip) also includes the following files: of06-1165_1b.txt a text file of FGDC compliant metadata for this Report import.aml an ARC/INFO Arc Macro Language file for importing the above coverage Converting ARC export files ARC export files are converted to ARC coverages using the ARC command IMPORT with the option COVER. To ease conversion and maintain naming conventions, we have included an ASCII text file in ARC Macro Language that will convert all of the export files in the database into coverages and create the associated INFO directory. With the Workspace set to the directory containing the Arc Export files, from the ARC command line type: Arc: &run import.aml ARC export files can also be read by some other Geographic Information Systems. Please consult your GIS documentation to see if you can use ARC export files and the procedure to import them. Note: consult the metadata or the Database Specifics section of this Report for details of the format and content of the digital database Plotfile Package For those interested in the geology of the map area whom don't use an ARC/INFO compatible GIS system, we have included a separate data package of printable maps created from the database. Because this release is primarily a digital database, the plot files (and plots derived from) have not been edited to conform to U.S. Geological Survey standards. Small units have not been labeled with leaders and in some instances map features or annotation overlap. The map image is 29 by 64 inches and requires a large plotter to produce paper copies at the intended scale. of06-1165_3a.eps A PostScript format file containing an image of the geologic map, at a scale of 1:100,000. of06-1165_3a.pdf A PDF format file containing an image of the geologic map, at a scale of 1:100,000.

  3. What legal disclaimers am I supposed to read?

    Use of the database beyond the intended map scale (1:100,000) is not recommended.

    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 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: 30-Jun-2006

Metadata author:
U.S. Geological Survey
c/o David R. Bedford
Geologist
345 Middlefield Rd MS973
Menlo Park, CA 94025
USA

650-329-4924 (voice)
650-329-4936 (FAX)
dbedford@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Metadata extensions used:

Generated by mp version 2.7.3 on Fri Jun 30 16:03:47 2006