A digital version of the 1970 US Geological Survey topographic map of the San Francisco Bay region, three sheets, 1:125,000

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Frequently anticipated questions:

What does this data set describe?

A digital version of the 1970 US Geological Survey topographic map of the San Francisco Bay region, three sheets, 1:125,000
This Open-File report is a digital topographic map database. It contains a digital version of the 1970 U.S. Geological Survey topographic map of the San Francisco Bay Region (3 sheets), at a scale of 1:125,000.
  1. How might this data set be cited?
    Aitken, Douglas S., 1997, A digital version of the 1970 US Geological Survey topographic map of the San Francisco Bay region, three sheets, 1:125,000: U.S. Geological Survey Open-File Report 97-500.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -123.75
    East_Bounding_Coordinate: -122.63
    North_Bounding_Coordinate: 38.88
    South_Bounding_Coordinate: 37.88
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1997
    publication date
  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.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      UTM_Zone_Number: 10
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123
      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
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview: Only ARC/INFO internal attribute values.
    Entity_and_Attribute_Detail_Citation: For more information download the file sftopo.txt

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Douglas S. Aitken
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Aitken, Douglas S
    Mail Stop 531, USGS
    345 Middlefield Rd
    Menlo Park, CA

    650-329-4388 (voice)

Why was the data set created?

To provide a digital topographic map of the San Francisco Bay region to the public.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 1970 (process 1 of 2)
    The topographic map information was digitized from stable originals (cronaflex mylar blackline positives) of the map separates at 1:125,000 scale. The following separates were scanned:
    1.  Composite of the culture, culture-names, land net and primary roads
    2.  Composite of the drainage and drainage names
    3.  Composite of intermediate and index contours
    4.  Secondary roads
    Scanning was done on a Scitex R280 at a resolution of 20 points/millimeter (508 dpi). The Scitex R280 was used to edit the raster scans and to separate the index and intermediate contours into separate coverages. The raster scans were then vectorized on the Scitex R280 with a curvetype of 1 and a tolerance of 1. The vectorization process distorts characters representing letters and numbers, as well as some other symbols, rendering them unreadable in some instances. The vectorized scans were imported into ARC/INFO using the SCITEXLINE command. ARC/INFO was used to modify edge joins, and to remove duplicate names (in adjacent sheets) and marginal information (to allow for mosaicing of adjacent sheets). Each file was converted from digitizer inches to UTM meters using latitude/longitude intersections on the scanned separates as reference points.
    Date: 08-Jun-2009 (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

    703-648-6974 (voice)
    703-648-6560 (FAX)
  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 topographic representation.
  5. How consistent are the relationships among the observations, including topology?
    Compiled from the 1970 US Geological Survey topographic map.

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)
    USGS Information Services
    Box 25286, Denver Federal Center
    Denver, Colorado

    1-888-ASK-USGS (voice)
    1-303-202-4695 (FAX)
  2. What's the catalog number I need to order this data set? US Geological Survey Open-File Report 97-500
  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 "A digital version of the 1970 U.S. Geological Survey topographic map of the San Francisco Bay Region, three sheets, 1:125,000," has been approved for release and publication by the Director of the USGS. Although this database has been reviewed and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. This database is released on condition that neither the USGS nor the U. S. Government may be held liable for any damages resulting from its use.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format:
      ARC/INFO coverage	Description of coverage
      Sheet 1 (sht1.tar.gz)
      sh1c.e00		Culture
      sh1d.e00		Drainage
      sh1ir.e00		Intermediate contours
      sh1ix.e00		Index contours
      sh1r.e00		Roads
      in format ARCE (version 7.x) Size: 9
      Network links: http://pubs.usgs.gov/of/1997/of97-500/sht1.tar.gz
      Data format:
      ARC/INFO coverage	Description of coverage
      Sheet 2 (sht2.tar.gz)
      sh2c.e00		Culture
      sh2d.e00		Drainage
      sh2ir.e00		Intermediate contours
      sh2ix.e00		Index contours
      sh2r.e00		Roads
      in format ARCE (version 7.x) Size: 18.3
      Network links: http://pubs.usgs.gov/of/1997/of97-500/sht2.tar.gz
      Data format:
      ARC/INFO coverage	Description of coverage
      Sheet 3 (sht3.tar.gz)
      sh3c.e00		Culture
      sh3d.e00		Drainage
      sh3ir.e00		Intermediate contours
      sh3ix.e00		Index contours
      sh3r.e00		Roads
      in format ARCE (version 7.x) Size: 24.3
      Network links: http://pubs.usgs.gov/of/1997/of97-500/sht3.tar.gz
    • Cost to order the data: none

Who wrote the metadata?

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

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

This page is <https://geo-nsdi.er.usgs.gov/metadata/open-file/97-500/metadata.faq.html>
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