Nahant to Gloucester, Massachusets Depth to Bedrock (bedrock_depth)

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Frequently anticipated questions:


What does this data set describe?

Title:
Nahant to Gloucester, Massachusets Depth to Bedrock (bedrock_depth)
Abstract:
These data are high-resolution seismic reflection profile data of the seafloor offshore of Massachusetts, from Nahant to Gloucester. Approximately 1,175 kms of seismic reflection profile data were collected using a Knudsen 320b chirp system
Data were processed using SIOSEIS (Scripps Institute of Oceanography) and Seismic Unix (Colorado School of Mines) to produce segy files and jpg images of the profiles. Data were then imported into Landmark SeisWorks, an interactive computer system where horizons were interpreted and digitized to calculate depth to reflectors below the seafloor. Interpreted depth to reflectors were calculated, exported every 5 shots, and then imported to ArcGIS for interpolation into a 50-m raster grid. These data were used to generate a sediment isopach map, which shows the total thickness of sediment that overlies bedrock
  1. How might this data set be cited?
    Andrews, Brian, 2005, Nahant to Gloucester, Massachusets Depth to Bedrock (bedrock_depth): Open File Report 2005-1293, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Barnhardt, Walter A., Andrews, Brian D., and Butman, Bradford, 2006, High-Resolution Mapping of the Inner Continental Shelf: Nahant to Gloucester, Massachusetts: Open-File Report 2005-1293, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.920415
    East_Bounding_Coordinate: -70.688114
    North_Bounding_Coordinate: 42.572416
    South_Bounding_Coordinate: 42.399158
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 22-Sep-2003
    Ending_Date: 07-May-2004
    Currentness_Reference:
    ground condition of 2 separate events: 20030922 to 20031015 and 20040412 to 20040507
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 377 x 374 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 50.000000
      Ordinates (y-coordinates) are specified to the nearest 50.000000
      Planar coordinates are specified in meters
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean lower low water
      Depth_Resolution: 9999
      Depth_Distance_Units: Information unavailable from original metadata.
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Brian Andrews
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Brian Andrews
    U.S. Geological Survey
    Marine Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov

Why was the data set created?

These data were collected under a cooperative agreement with the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center. High resolution bathymetry, backscatter intensity, and seismic profile data were collected over 127 km² area covering a portion of the South Essex Ocean Sanctuary to characterize the surface and subsurface of the seafloor for regional geologic framework investigations.
Bathymetric data were collected during two different surveys. Survey RAFA03007 began Monday, 22 Sep 2003 (JD267) and ended on Tuesday, 14 Oct 2003 (JD287). RAFA04002 began 17 Apr 2004 (JD 108) and ended on 2 May 2004 (JD123).

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: unknown (process 1 of 7)
    Seismic profiles were interpreted in Landmark software. Each seismic profile was reviewed and acoustic reflectors were digitized.
    Date: unknown (process 2 of 7)
    Interpreted horizons were exported as x,y,z (depth to reflector) and then imported to ArcGIS as point feature class for interpolation using Geostatistical Analyst.
    Date: unknown (process 3 of 7)
    Shot data with depth to reflector was interpolated using ArcGIS Geostatistical Analyst with the following parameters
    Selected Method: Universal Kriging Output: Prediction Map
    Number of datasets currently in use: 1
    Number of Points: 326304
    Order of Trend: Const (Estimated by Global Polynomial Interpolation)
    Semivariogram/Covariance: Model: 69.118*Spherical(1625.9)+31.914*Nugget Error modeling: Microstructure: 31.914 (100%) Measurement error: 0 (0%)
    Searching Neighborhood: Neighbors to Include: 9 or at least 4 for each angular sector Searching Ellipse: Angle: 0 Major Semiaxis: 1625.9 Minor Semiaxis: 162
    Date: 22-Dec-2017 (process 4 of 7)
    Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Added the link to the data catalog page in the Identification section. The link to the larger work citation had to be fixed. Added the online link to the data in the distribution section. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The depth system definition was incomplete. Generic values (such as 9999) were used to meet the standard. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 5 of 7)
    USGS Thesaurus keywords added to the keyword section. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 18-Nov-2019 (process 6 of 7)
    Crossref DOI link was added as the first link in the metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 08-Sep-2020 (process 7 of 7)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@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?
    Seismic data are not corrected for tides. The bedrock depth (sediment thickness) is calculated as the distance between the bedrock and the seafloor from interpretation of seismic reflection profiles.
  4. Where are the gaps in the data? What is missing?
    Information unavailable from original metadata.
  5. How consistent are the relationships among the observations, including topology?
    These data have not been quantitatively compared to previous hydrographic data, although they generally agree with qualitative comparison of published NOAA charts.

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:
Data are not intended for navigational use.
These data should not be used at resolutions for which it is not intended.
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  1. Who distributes the data set? (Distributor 1 of 1)
    Brian Andrews
    U.S. Geological Survey, Woods Hole Science Center
    Marine Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
  2. What's the catalog number I need to order this data set? Downloadable Data
  3. What legal disclaimers am I supposed to read?
    Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.
    Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data are available in Environmental Systems Research Institute (ESRI) GRID format. The user must have software capable of importing and processing the data file.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
Brian Andrews
U.S. Geological Survey
Marine Geographer
384 Woods Hole Rd.
Woods Hole, MA
USA

508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2005-1293/bedrock_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:20:20 2021