GIS Metadata

BLM OR Quads 1:63,360 (30-Minute) Polygon

Frequently-asked questions:

What does this data set describe?

BLM OR Quads 1:63,360 (30-Minute) Polygon

QUADS30M_POLY: This theme shows the 1:63,360 quadrangles (30 Minute Quads) for Oregon and Washington as defined in North American Datum 1927 (NAD27). These quads show the approximate extent of and align with the NAD27 corner ticks as displayed on USGS Topoquads.

Supplemental information:
BLM (Bureau of Land Management), USGS (United States Geological Survey), GNIS (Geographical Names Information System), NGNDB (National Geographic Names DataBase) As described in the process steps these data were created on a regular grid of latitude/longitude to depict the 1:63,360 quadrangles covering Oregon and Washington and the surrounding areas as defined in North American Datum 1927 (NAD27). Due to the fact the dataset was originally created in NAD27 the values of coordinates defining the corners of the quads will only be those of the definition in the original datum. Once data is projected to a different datum the values will be correctly modified mathematically to reflect the change to the new projection. These quads show the approximate extent of the USGS topographic quadrangles. Since this data is constructed from corner points with straight lines connecting the corners, it does not take into account the curve between corner points introduced by the use of the UTM projection used to produce the topoquad maps. Thus this dataset is only a depiction of the extent of the topoquad. The corners of each of these quadrangles should align with the NAD27 ticks displayed on USGS topoquads in any projection used.

  1. How should this data set be cited?

    BLM and USGS, 20020101, BLM OR Quads 1:63,360 (30-Minute) Polygon.

    Other citation details:

  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -125
    East: -116
    North: 49
    South: 41

  3. What does it look like?

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

    Calendar date: 20020101
    Currentness reference:
    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?

      Indirect spatial reference:
      Oregon Washington

      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • GT-polygon composed of chains (324)

    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 2e-008. Longitudes are given to the nearest 2e-008. Latitude and longitude values are specified in Decimal Degrees.

      The horizontal datum used is D North American 1983.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.

  7. How does the data set describe geographic features?

    30-Minute Quad Polygons
    Polygons at intervals of 30 Minutes of latitude and longitude (Source: BLM)

    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    The USGS Ohio code for the 30-minute quad, with the row/column coding listed first. (Source: BLM)

    A name up to 30 characters long. This will be the most current name given to a 30M quad, as determined by the source of the name. (Source: BLM)

    source of the name for the quad. (Source: BLM)

    100k Name used
    15M Name used
    7.5M Name used
    No Name used
    Existing Name used

    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    Entity and attribute overview:
    The format of the quad code, in attribute q30, is translated from the format typically provided by USGS. Translation is required for use in many database programs (e.g. Informix, Oracle) because often, when dealing with a character field, the database program will not accept a numeral in the first space.
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Who produced the data set?

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

    • BLM and USGS

  2. Who also contributed to the data set?

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

    Corey Plank
    Bureau of Land Management
    Lead Cartographer
    P.O. Box 2965
    Portland, OR97201

    (503) 808-6427 (voice)
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Why was the data set created?

Resource Management Planning

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How was the data set created?

  1. Where did the data come from?

    USGS Map Name (source 1 of 3)

    USGS, 19940501, USGS 7.5 Minute Quadrangles.

    Type of source media: hardcopyPaper
    Source scale denominator: 24000
    Source contribution:

    USGS NGNDB (source 2 of 3)

    USGS, 19980301, National Geographic Names DataBase.

    Type of source media: None
    Source contribution:

    BLM QUADS30m (source 3 of 3)

    BLM, 20020101, BLM QUADS30m.

    Type of source media: onLine
    Source contribution:

  2. What changes have been made?

    Date: 20000401 (change 1 of 1)
    This coverage was generated in Arc/Info using a computer program that created the polygons at 30-minute intervals of latitude and longitude. Another computer program used the latitude/longitude of the SE corner of the polygons to calculate their Ohio codes. The GNIS NGNDB was related to the Ohio codes to populate the common names field. GNIS NGNDB was compared to a USGS maps, and where quad names disagreed, the name from the USGS map populated the name field. The BLM archives were search for 30-minute series maps. Where they found the name of those maps, they were used to populate the name field. Where no USGS or BLM map was found, names of the 100k USGS map series were use to populate a quad name. When two quads required names only the quad that covered the feature for which the 100k map was named by was named using that name. For those remaining the name of one 7.5 Minute map within the polygon boundary was use to populate the name field.

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

  1. How well have the observations been checked?

    The Ohio codes were generated based on the latitude/longitude of the SE corner of the polygon. The common names were attributed from one of four sources if the quad covered some portion of Oregon. From an existing, or once used, USGS Map name. From an existing, or once used, BLM map name. For the 100k map that covers the same area. For the 7.5 minute map that covers the same area. Source for the map name is noted in the SOURCE attribute.

  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?

    This theme covers all lands in Oregon and Washington as well as parts of California, Nevada, Idaho, British Columbia, Alberta and the Pacific Ocean. Only quads covering Oregon are attributed with common names.

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

    This theme was created by generating the lines at a .500 degree interval. There are no node errors or open polygons. This theme was built with polygon topology. The original defined datum is NAD27.

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How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access constraints: PUBLIC DATA: None, these data are considered public domain.
Use constraints:
These data are provided by Bureau of Land Management (BLM) "as is" and may contain errors or omissions. The User assumes the entire risk associated with its use of these data and bears all responsibility in determining whether these data are fit for the User's intended use. The information contained in these data is dynamic and may change over time. The data are not better than the original sources from which they were derived, and both scale and accuracy may vary across the data set. These data may not have the accuracy, resolution, completeness, timeliness, or other characteristics appropriate for applications that potential users of the data may contemplate. The User is encouraged to carefully consider the content of the metadata file associated with these data. These data are neither legal documents nor land surveys, and must not be used as such. Official records may be referenced at most BLM offices. Please report any errors in the data to the BLM office from which it was obtained. The BLM should be cited as the data source in any products derived from these data. Any Users wishing to modify the data should describe the types of modifications they have performed. The User should not misrepresent the data, nor imply that changes made were approved or endorsed by BLM. This data may be updated by the BLM without notification.

Distributor 1 of 1

  1. Who distributes the data set?

    Eric Hiebenthal
    Bureau of Land Management
    GIS Data Management Specialist
    P.O Box 2965
    Portland, OR97208

    503-808-6340 (voice)
    503-808-6419 (FAX)
    Contact Instructions:
    contact instructions

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

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    The BLM assumes no responsibility for errors or omissions. No warranty is made by the BLM as to the accuracy, reliability, or completeness of these data for individual use or aggregate use with other data; nor shall the act of distribution to contractors, partners, or beyond, constitute any such warranty for individual or aggregate data use with other data. Although these data have been processed successfully on computers of BLM, no warranty, expressed or implied, is made by BLM regarding the use of these data on any other system, or for general or scientific purposes, nor does the fact of distribution constitute or imply any such warranty. In no event shall the BLM have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of the use or reliance on the geographic data or arising out of the delivery, installation, operation, or support by BLM.

  4. How can I download or order the data?

    • Cost to order the data: Contact distributor.

    • Special instructions:

      Data are only available through the Oregon/Washington State office of the Bureau of Land Management.

  5. Is there some other way to get the data?

  6. What hardware or software do I need in order to use the data set?

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Who wrote the metadata?

Last modified: 20030101
Last reviewed: 20141114

Metadata author:
Roger Mills
Bureau of Land Management, Oregon State Office
GIS Specialist
P.O. Box 2965
Portland, OR97208

(503) 808-6340 (voice)
(503) 808-6419 (FAX)
Hours of Service: 8:00-4:00
Contact Instructions:

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

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