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USGS Geoscience Data Catalog

Geologic Map of the East of Grotto Hills Quadrangle, California: A Digital Database

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Frequently anticipated questions:


What does this data set describe?

Title:
Geologic Map of the East of Grotto Hills Quadrangle, California: A Digital Database
Abstract:
This digital map database represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (egh_geo.txt, egh_geo.pdf or egh_geo.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.
  1. How might this data set be cited?
    Nielson, Jane E., and Bedford, David R., 1999, Geologic Map of the East of Grotto Hills Quadrangle, California: A Digital Database: U.S. Geological Survey Open-File Report 99-35.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -115.13
    East_Bounding_Coordinate: -115.00
    North_Bounding_Coordinate: 35.25
    South_Bounding_Coordinate: 35.13
  3. What does it look like?
    http://pubs.usgs.gov/of/1999/0035/pdf/egh_map.pdf (PDF)
    PDF representation of the geologic map of the East of Grotto Hills Quadrangle, California at a scale of 1:24000
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1999Currentness_Reference: Publication date of the digital 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: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 11
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -117
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest unknown
      Ordinates (y-coordinates) are specified to the nearest unknown
      Planar coordinates are specified in meters
      The horizontal datum used is NAD27.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.
      The flattening of the ellipsoid used is 1/2943.98.
  7. How does the data set describe geographic features?
    EGH_GEOL.PAT
    Geologic map units (Source: OFR-99-35)
    PTYPE
    Polygon type (Source: OFR-99-35)
    ValueDefinition
    QtsTalus and scree (Holocene)
    QyaYounger alluvium (Holocene)
    QauOlder, intermediate, and younger alluvium, undivided (Holocene and Pleistocene?)
    Qia2bIntermediate alluvium (Holocene and Pleistocene?) - Unit 2 - Younger deposits (Holocene)
    Qia2aIntermediate alluvium (Holocene and Pleistocene?) - Unit 2 - Older deposits (Holocene and Pleistocene?)
    Qia1bIntermediate alluvium (Holocene and Pleistocene?) - Unit 1 - Younger deposits (Holocene)
    Qia1aIntermediate alluvium (Holocene and Pleistocene?) - Unit 1 - Older deposits (Holocene and Pleistocene?)
    QoaOlder alluvium (Pleistocene)
    QTpPlaya and lacustrine deposits (Pleistocene? to Miocene)
    TgGravel deposits (Miocene)
    TbtsBasalt flows, rhyolite tuff, and sedimentary rocks (Miocene)
    TbBasalt flows (Miocene)
    TatsAndesitic flows and intrusions, silicic tuff, and sedimentary rocks (Miocene)
    TaAndesitic flows, breccia, and sedimentary rocks (Miocene)
    TdDacite flows and intrusions (Miocene)
    TrRhyolite tuff and flows (Miocene)
    TtsTuff, volcanic breccia, and sedimentary rocks (Miocene)
    TprTuff of the Piute Range (Miocene)
    TidDacitic intrusions (Miocene)
    EGH_GEOL.AAT
    Linear geologic features (Source: OFR-99-35)
    LTYPE
    Line Type (Source: OFR-99-35)
    ValueDefinition
    contact, certainContact that was observed
    fault, approx. locatedFault whose position is not certain
    fault certainobserved fault
    fault, concealedFault whose position is concealed and inferred
    map boundary, certainBoundary of mapped area
    EGH_GEOL.PAT
    Geologic map units at specific points (Source: OFR-99-35)
    PTYPE
    Point Type (Source: OFR-99-35)
    ValueDefinition
    QtsTalus and scree (Holocene)
    QyaYounger alluvium (Holocene)
    QauOlder, intermediate, and younger alluvium, undivided (Holocene and Pleistocene?)
    Qia2bIntermediate alluvium (Holocene and Pleistocene?) - Unit 2 - Younger deposits (Holocene)
    Qia2aIntermediate alluvium (Holocene and Pleistocene?) - Unit 2 - Older deposits (Holocene and Pleistocene?)
    Qia1bIntermediate alluvium (Holocene and Pleistocene?) - Unit 1 - Younger deposits (Holocene)
    Qia1aIntermediate alluvium (Holocene and Pleistocene?) - Unit 1 - Older deposits (Holocene and Pleistocene?)
    QoaOlder alluvium (Pleistocene)
    QTpPlaya and lacustrine deposits (Pleistocene? to Miocene)
    TgGravel deposits (Miocene)
    TbtsBasalt flows, rhyolite tuff, and sedimentary rocks (Miocene)
    TbBasalt flows (Miocene)
    TatsAndesitic flows and intrusions, silicic tuff, and sedimentary rocks (Miocene)
    TaAndesitic flows, breccia, and sedimentary rocks (Miocene)
    TdDacite flows and intrusions (Miocene)
    TrRhyolite tuff and flows (Miocene)
    TtsTuff, volcanic breccia, and sedimentary rocks (Miocene)
    TprTuff of the Piute Range (Miocene)
    TidDacitic intrusions (Miocene)
    EGH_SMPL.PAT
    Dated Sample localities in the East of Grotto Hills 7.5 minute quadrangle (Source: OFR-99-35)
    PTTYPE
    Point Type (Source: OFR-99-35)
    ValueDefinition
    sampleSample location
    SAMPNO
    Sample number (Source: OFR-99-35)
    Range of values
    Minimum:6
    Maximum:10
    EGH_STR.PAT
    Strike and dip information in the East of Grotto Hills 7.5 minute quadrangle (Source: OFR-99-35)
    PTTYPE
    Point Type (Source: OFR-99-35)
    ValueDefinition
    jointjoint position
    beddingbedding position
    horz foliationHorizontal foliation location (strike and dip are both 0)
    DIP
    Dip of bedding (Source: OFR-99-35)
    Range of values
    Minimum:5
    Maximum:52
    Units:degrees
    Resolution:1
    STRIKE
    Strike of bedding (Source: OFR-99-35)
    Range of values
    Minimum:101
    Maximum:311
    Units:degrees
    Resolution:1
    Entity_and_Attribute_Overview:
    ARC/INFO export files:
    egh_geol.e00 - Faults, depositional contacts, and rock units in the East of Grotto Hills 7.5 minute quadrangle
    egh_str.e00 - Strike and dip information in the East of Grotto Hills 7.5 minute quadrangle
    egh_smpl.e00 - Dated Sample localities in the East of Grotto Hills 7.5 minute quadrangle
    egh_topo.e00 - Topographic base map taken from a scan of the East of Grotto Hills topographic quadrangle.
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/of/1999/0035/pdf/egh_geo.pdf

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?
    Jane E. Nielson
    US Geological Survey
    US Geological Survey, 345 Middlefield Rd, MS 975
    Menlo Park, CA
    USA


Why was the data set created?

This Open-File report is a digital geologic map database. This pamphlet serves to introduce and describe the digital data. There is no paper map included in the Open-File report. The report does include, however, PostScript and PDF plot files containing images of a geologic map sheet, as well as the accompanying text describing the geology of the area. For those interested in a paper plot of information contained in the database or in obtaining the PostScript plot files, please see the section entitled "For Those Who Don't Use Digital Geologic Map Databases" below.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    (process 1 of 2)
    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 an 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, unit boundaries were tagged as appropriate, and scanning artifacts were removed. The Topographic Base Map layer was prepared from a scan of standard U.S. Geological Survey 7.5 minute topographic quadrangle on an Altek monochrome scanner at 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. Because the base map is for reference only, scanning artifacts have not been removed from this map.
    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 was compilied from a variety of different sources.

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 25286, Denver Federal Center
    Denver, CO
    USA

    1-888-ASK-USGS (voice)
    1-303-202-4695 (FAX)
    infoservice@usgs.gov
  2. What's the catalog number I need to order this data set?
  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 "Geologic Map of the East of Grotto Hills Quadrangle, California: A Digital 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: 10-Jun-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/99-35/metadata.faq.html>

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Page Last Modified: Monday, 14-Aug-2017 12:02:01 EDT

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