1997 Seismic Tracklines in Geographic Coordinates

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Frequently-anticipated questions:

What does this data set describe?

    Title: 1997 Seismic Tracklines in Geographic Coordinates
    Abstract:
    Two 21-day field operations were conducted in 1997 and 1998 in the estuaries and on the inner continental shelf off the northern Oregon and southern Washington coast. These cruises aboard the R/V Corliss were run in order to generate reconnaissance maps of the seafloor geology and the shallow subsurface stratigraphy using sidescan sonar and seismic-reflection mapping techniques. The 1998 cruise also collected sediment grab samples, bottom photographs, and video images to verify the sidescan-sonar imagery and to document the seafloor geology. The combination of these data with previously collected sediment sample data (Robert, 1974; Nittrouer, 1978; and Smith et. al., 1980) has been used to define the extent and lithology of shelf sediments associated with the Columbia River littoral cell. This work is one component of a larger project studying the erosion of the Washington and Oregon coast and is being coordinated by the U.S. Geological Survey and the Washington State Department of Ecology. The reason for collecting these data is to provide a regional synthesis of the offshore geology to support a wide variety of management decisions and to provide a basis for further process-oriented investigations.
    Supplemental_Information:
    Roberts, R.W., 1974, Marine sedimentological data of the Washington continental shelf: University of Washington, Department of Oceanography Special Report 57, 129p.

    Nittrouer, C.A., 1978, The process of detrital sediment accumulation in a continental shelf environment: an examination of the Washington shelf: PhD Thesis, University of Washington, Seattle, WA. 243p.

    Smith, J.M., Messmer, L.W., Phipps, J.B., Samuelson, D.F., and Schermer, E.D., 1980, Grays Harbor and Chehalis River improvements to navigation environmental studies - Grays Harbor ocean disposal study: literature review and preliminary benthic sampling: U.S. Army Corps of Engineers Internal Report.

  1. How should this data set be cited?

    Twichell, David C. , and Cross, VeeAnn A. , 20010716, 1997 Seismic Tracklines in Geographic Coordinates: U.S. Geological Survey, Woods Hole, MA.

    This is part of the following larger work.

    Twichell, David C. , and Cross, VeeAnn A. , 20011000, Holocene Evolution of the Southern Washington and Northern Oregon Shelf and Coast: Geologic Discussion and GIS Data Release: U.S. Geological Survey Open-File Report Report 01-076.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -124.450840
    East_Bounding_Coordinate: -123.946770
    North_Bounding_Coordinate: 47.341170
    South_Bounding_Coordinate: 45.944580

  3. What does it look like?

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

    Calendar_Date: 16-Jul-2001
    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?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • String (82)

    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 0.00018. Longitudes are given to the nearest 0.00026. Latitude and longitude values are specified in Decimal degrees.

      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?

    seisnav97g.dbf
    ArcView shapefile attribute table (Source: ESRI)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    ID
    Feature ID necessary to convert the point file to a polyline file using pt2ln2pl.avx. (Source: User defined.)

    Range of values
    Minimum:1
    Maximum:82

    LINENUM
    The seismic file the line represents. (Source: Defined aboard ship.)

    character set

    HTMLINK
    String indicating the location of the HTML document to hotlink to for that particular line segement. (Source: User defined.)

    character set

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 C. Twichell
    USGS
    Oceanographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
    dtwichell@usgs.gov

Why was the data set created?

This GIS overlay is a component of the Southwest Washington Coastal Erosion ArcView GIS database. This particular overlay represents the navigation tracklines for the seismic data collected in 1997.

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: 01-Mar-2001 (process 1 of 1)
    The system used to acquire seismic data did not record frequent navigation points. In order to alleviate this problem, navigation was extracted directly from the main navigation based on file start time, the few seismic shot navigation points, and extrapolation based on 0.5 sec fire rate of the seismics. This navigation file was run through an awk script so that the navigation file could be brought into ArcView and converted to polylines using the sample extension from the ESRI website "pt2ln2pl.avx". The event table was processed using the extension as a continuous line. This new shapefile was then edited to added the "htmlink" field which enables hotlinking to html files contained seismic profiles.

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?

    This data is complete for this particular study.

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

    Consistent.

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:
The U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data.

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

    David C. Twichell
    USGS
    Oceanographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
    dtwichell@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 Compact Disc-Read Only Memory (CD-ROM) publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitude or imply its endorsement, recommendation, or favoring by the United States Governemnt or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data published on this CD-ROM have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 10-Aug-2001

Metadata author:
VeeAnn A. Cross
USGS
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543
USA

508-548-8700 (voice)
508-457-2310 (FAX)
vatnipp@usgs.gov

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

Metadata extensions used:

Generated by mp (URL: https://geology.usgs.gov/tools/metadata/tools/doc/mp.html ) version 2.7.3 on Fri Nov 16 16:35:00 2001