Generalized Geology of the World and Linked Databases, Open File 2915d

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Frequently anticipated questions:

What does this data set describe?

Generalized Geology of the World and Linked Databases, Open File 2915d
The Generalized Geology of the World is a highly simplified digital geological data set composed of geographically referenced rock unit patchworks and fault lines which can be combined with tables of descriptive data. The latter, hereafter referred to as attribute tables, includes broadly classified age, main rock or fault type, and name information.
  1. How might this data set be cited?
    Geological Survey of Canada, 1995, Generalized Geology of the World and Linked Databases, Open File 2915d: Geological Survey of Canada, Ottawa, Canada.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -180.0
    East_Bounding_Coordinate: 180.0
    North_Bounding_Coordinate: 90.0
    South_Bounding_Coordinate: -90.0
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1995
    publication date
  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):
      • GT-Polygon composed of chains (7562 polygons)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000464. Longitudes are given to the nearest 0.000464. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6370997 meters.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview: Fullname : Age at the era level and Main Rock Type
    Entity_and_Attribute_Detail_Citation: Geological Survey of Canada Open File 2915d

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Geological Survey of Canada
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Geological Survey of Canada
    601 Booth Street
    Ottawa, Ontario

Why was the data set created?

The purpose of this data set is threefold: (1) to provide the basic context for the display of global distribution patterns of geoscientific data; (2) to allow the preparation of simple, global-scale, customized thematic maps and page-sized diagrams using a range of GIS overlay and logical selection techniques on the currently available data, alone or in combination with other data; and (3) to provide a basic geological data set which can be experimented with before designing other regional geological GIS products.

As a note of caution, displays from this data set are not valid enlarged to scales much larger than 1:35 million, and should NOT be used for quantitative analyses of any sort. The generalization level is extremely high, as discussed in the generalization section below. GIS overlay of additional data should be used only with careful consideration of the level of generalization. Conceptually, overlain data should be as highly generalized as the age and rock type and fault background layers, and the product of the overlay envisaged as a global-scale visual pattern rather than a quantitative correlation.

How was the data set created?

  1. From what previous works were the data drawn?
    GSC (source 1 of 1)
    ESRI, 1995, Generalized Geological Map of the World and Linked Databases.

    Type_of_Source_Media: digital
    Source_Scale_Denominator: 35000000
    The preparation of the digital data and the Generalized Geology of the World hard copy map was accomplished under the auspices of the Geoscience Information and Communication Division, Geological Survey of Canada, particularly the Digital Cartography Section, and the Mineral Resources Division.
  2. How were the data generated, processed, and modified?
    Date: 2001 (process 1 of 1)
    The Generalized Geology datasets (ESRI export files) were imported into ArcInfo 8.1 and seven coverages were created (Rock Unit Polygons), namely: Africa/Arabian, Antarctica, Asia, Australia, Europe, North America, South America. Using the unique coverage id field (field relate) the coverage attributes were linked to each data table for rock units. The seven coverages were then combined into a single world geology coverage and this dataset was converted to an ArcView 3.2 shapefile. Person who carried out this activity:
    Tom Kress
    U.S. Geological Survey
    12201 Sunrise Valley Dr.
    Reston, VA

    703-648-6328 (voice)
  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?
    The accuracy of the Generalized Geological Map of the World attributes is unknown according to the metadata from the Geological Survey of Canada (GSC).
  2. How accurate are the geographic locations?
    The horizontal accuracy of the digital data was provided by GSC and is claimed to be no better than the original source data 1:35,000,000.
  3. How accurate are the heights or depths?
    The vertical accuracy is unknown.
  4. Where are the gaps in the data? What is missing?
    None of the data from the Generaized Geological data was omitted.
  5. How consistent are the relationships among the observations, including topology?
    Chain-node topology present

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)
    Geological Survey of Canada
    601 Booth Street
    Ottawa, Ontario

  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    The U.S. Geological Survey (USGS) provides this vector data "as is." The USGS makes no guarantee or warranty concerning the accuracy of information contained in the image data. The USGS further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although this data has been processed successfully on computers at the USGS, no warranty, expressed or implied, is made by the USGS regarding the use of this data on any other system, nor does the fact of distribution constitute or imply any such warranty.
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 07-Mar-2018
Metadata author:
Peter N Schweitzer
USGS Eastern Mineral and Environmental Resources Science Center
12201 Sunrise Valley Drive
Reston, VA

703-648-6533 (voice)
703-648-6252 (FAX)
Metadata standard:
FDGC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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