Polyline shapefile of a portion of the 1-meter (m) contours in quadrangle 6 of the Stellwagen Bank Survey Area offshore of Boston, Massachusetts necessary to show small features not displayed by 5-m contours - based on bathymetry data collected by the U.S. Geological Survey from 1994-1996 (Geographic, NAD 83)

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:


What does this data set describe?

Title:
Polyline shapefile of a portion of the 1-meter (m) contours in quadrangle 6 of the Stellwagen Bank Survey Area offshore of Boston, Massachusetts necessary to show small features not displayed by 5-m contours - based on bathymetry data collected by the U.S. Geological Survey from 1994-1996 (Geographic, NAD 83)
Abstract:
The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration's National Marine Sanctuary Program, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary region since 1993. The area is approximately 3,700 square kilometers (km2) and is subdivided into 18 quadrangles. Seven maps, at a scale of 1:25,000, of quadrangle 6 (211 km2) depict seabed topography, backscatter, ruggedness, geology, substrate mobility, mud content, and areas dominated by fine-grained or coarse-grained sand. Interpretations of bathymetric and seabed backscatter imagery, photographs, video, and grain-size analyses were used to create the geology-based maps. In all, data from 420 stations were analyzed, including sediment samples from 325 locations. The seabed geology map shows the distribution of 10 substrate types ranging from boulder ridges to immobile, muddy sand to mobile, rippled sand. Substrate types are defined on the basis of sediment grain-size composition, surficial morphology, sediment layering, and the mobility or immobility of substrate surfaces. This map series is intended to portray the major geological elements (substrates, features, processes) of environments within quadrangle 6. Additionally, these maps will be the basis for the study of the ecological requirements of invertebrate and vertebrate species that utilize these substrates and guide seabed management in the region.
  1. How might this data set be cited?
    Valentine, Page C., 2015, Polyline shapefile of a portion of the 1-meter (m) contours in quadrangle 6 of the Stellwagen Bank Survey Area offshore of Boston, Massachusetts necessary to show small features not displayed by 5-m contours - based on bathymetry data collected by the U.S. Geological Survey from 1994-1996 (Geographic, NAD 83): Scientific Investigations Map 3341, 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.

    Valentine, Page C., and Gallea, Leslie B., 2015, Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 6 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: Scientific Investigations Map 3341, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.221962
    East_Bounding_Coordinate: -70.033546
    North_Bounding_Coordinate: 42.322269
    South_Bounding_Coordinate: 42.202885
  3. What does it look like?
    http://pubs.usgs.gov/sim/3341/data/SIM3341_1m_contours.jpg (JPEG)
    Thumbnail image showing the 1-meter contours in quadrangle 6 on Stellwagen Bank National Marine Sanctuary.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1994
    Ending_Date: 1996
    Currentness_Reference:
    ground condition
  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 (846)
    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 0.000001. Longitudes are given to the nearest 0.000001. 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.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean lower low water
      Depth_Resolution: 1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    SIM3341_1m_contours
    Portion of the 1 meter contours that fall within quadrangle 6 of the Stellwagen Bank study area. (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: ESRI) Coordinates defining the features.
    CONTOUR
    These values represent depth. The more negative the value, the deeper the water. Depths are relative to mean lower low water datum. (Source: U.S. Geological Survey)
    Range of values
    Minimum:-36
    Maximum:-183
    Units:meters
    Resolution:1

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Page C. Valentine
  2. Who also contributed to the data set?
    Public domain data from the U.S. government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the source of this information.
  3. To whom should users address questions about the data?
    Page C. Valentine
    U.S. Geological Survey
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov

Why was the data set created?

The purpose of this dataset is to release the 1-meter (m) contours that are used in quadrangle 6 Stellwagen Bank geologic interpretation maps. The 5-m contours, especially where they are widely spaced, do not adequately show the characteristic hummocky relief of the seabed in areas dominated by gravel deposits and small boulder ridges. Therefore, in areas of relatively rough seabed, the 5-m contours are supplemented by 1-m contours. The 1-m contours accentuate low-relief topographic complexity in these areas. The contours represent a close approximation of seabed microtopography, as the resolution of the multibeam echo sounder data used to generate these data is on the order of 1 m. By contrast, 1-m contours are not shown in areas where the seabed is relatively smooth and not dominated by gravel features. Any topographic complexity in these areas is beyond the resolution of the multibeam echosounder (< 1 meter in relief) and cannot be accurately depicted by the 1-m bathymetric contours.

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: 1996 (process 1 of 9)
    Initial data collection and processing is described in Valentine and others 1999, Valentine 2005, and Butman and others, 2007. A summary of that information is presented here. Surveying was conducted aboard the Canadian Hydrographic Service vessel Frederick G. Creed using a hull mounted multibeam echo sounder. These data were collected using a Simrad Subsea EM1000 operating at 95 kHz. SwathEd software (version unknown) developed by the Ocean Mapping Group, University of New Brunswick, was used to process the bathymetric and navigation data. The processing included editing the data to remove spurious points as well as incorporate tidal corrections. Processing took place over a span of time, 1994 to 1996.
    Date: 1997 (process 2 of 9)
    The remaining process steps are a function of incorporating information from the previous publications (noted in cross-references), along with processing notes maintained during data processing. The final SwathEd-produced file (based on a 10-meter-grid cell size) was converted to an ASCII file using the University of New Brunswick script r4toASCII. The format of the ASCII file is latitude, longitude, and depth. The ASCII file was converted to an ArcInfo ungenerate format using a Perl script. The resulting format is ID, longitude, latitude, and negative depth. Each point has a unique ID value. Using ArcInfo 7.03, the ungenerate format was converted to a coverage format using the 'convert to arc' from 'generate tool' available in ArcTools. The 'build' command with the point option was then used to convert the data to a point coverage. This procedure generates the point locations stored in the ungenerate file, but does not incorporate the depth values. In order to include depth, the ungenerate file - which has location as well as depth - was converted to an ArcInfo table, using 'Tables' in ArcInfo. The structure of the ArcInfo table was defined to include the ID, longitude, latitude, and depth in the appropriate format and size. Longitude and latitude were defined as floating point numbers with six decimal places, while depth was defined as a floating point number with two decimal places. To add the depth value to the point coverage, ArcInfo 'Tables' was used to join the point attribute table (pat) of the coverage to the newly-generated data table based on the ID value. In order to join the tables, the data table ID field had to be renamed to match the automatically assigned coverage ID field. The projection of the point coverage was defined in ArcInfo with the PROJECTDEFINE command and the following parameters: Projection Geographic; Datum NAD83; Units DD; Spheroid GRS80. This process was performed by Jessica Baker in 1997. Then the coverage was projected to the custom Mercator projection using the ArcInfo PROJECT command with the following options: Projection Mercator; Datum NAD83, Spheroid GRS1980; Units Meters; Longitude of Central Meridian -70degrees 19minutes; Latitude of true scale 41degrees 39minutes; False Easting 0; False northing 0. This process was performed by Jessica Baker in 1997. The final step was to convert the points to a grid. This was accomplished using the ArcInfo 'pointgrid' command. The depth attribute was gridded at a cell-size of 13 m, and the background value was set to nodata. This final processing step was performed in 1997, and is the basis for the subsequent work with contours. However, this process was repeated by Tammie Middleton in 2001 and is the grid presented in this SIM. The 13-m cell-size was chosen because it appeared to be the best cell size to avoid striping in the data when processing with the SwathEd software.
    Date: 1999 (process 3 of 9)
    The original Mercator grid was projected to a geographic coordinate system using the ArcInfo PROJECT command. Once this was done, the Arc/Info routine lattice contour was used to generate the 1-m contours. Extensive editing was done with ArcEdit to remove contours from areas where the seabed is relatively smooth and small features cannot be contoured based on the multibeam bathymetric data. Although each quadrangle was contoured independently, the contours were manually edited to remove "boundary faults". All of the editing work was done by Jessica Baker and Tanya Unger from 1997 to 1999. Data sources produced in this process:
    • arc6ctr1geo
    Date: 2012 (process 4 of 9)
    The 1-m coverage file was added to ArcMap 9.3.1. This dataset was then exported to a shapefile. This process step and the subsequent process step were performed by the same person: VeeAnn A. Cross. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • arc6ctr1geo
    Data sources produced in this process:
    • Q6_1m_contours.shp
    Date: 2012 (process 5 of 9)
    Metadata for the 1-m contours was compiled to enable releasing the data as part of a USGS publication. The information used to pull together the metadata was from previous publications, the extensive data processing log prepared by Tanya Unger and Jessica Baker, as well as the individual log files generated during ArcInfo data processing. While writing the metadata, seven records with a contour value of zero were found. It was determined that these contours were erroneous so they were deleted. Data sources used in this process:
    • Q6_1m_contours.shp
    Data sources produced in this process:
    • Q6_1m_contours.shp
    Date: 2012 (process 6 of 9)
    Removed the attributes associated with the original coverage that were not necessary for the shapefile (such as FNODE, TNODE). Data sources used in this process:
    • Q6_1m_contours.shp
    Data sources produced in this process:
    • Q6_1m_contours.shp
    Date: Sep-2015 (process 7 of 9)
    Renamed the shapefile after review to coincide with the publication series number. Data sources used in this process:
    • Q6_1m_contours.shp
    Data sources produced in this process:
    • SIM3341_1m_contours.shp
    Date: 20-Jul-2018 (process 8 of 9)
    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: 08-Sep-2020 (process 9 of 9)
    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?
    Valentine, Page C., Unger, Tanya S., Baker, Jessica L., and Polloni, Christopher F., 1999, Sun-illuminated sea floor topographic maps and perspective-view imagery of quadrangles 1-18, Stellwagen Bank National Marine Sanctuary off Boston, Massachusetts: Open-File Report 99-363, U.S. Geological Survey, Reston, VA.

    Online Links:

    Page C. Valentine, editor, 2005, Sea floor image maps showing topography, sun-illuminated topography, backscatter intensity, ruggedness, slope, and the distribution of boulder ridges and bedrock outcrops in the Stellwagen Bank National Marine Sanctuary region off Boston, Massachusetts: Scientific Investigations Map 2840, U.S. Geological Survey, Reston, VA.

    Online Links:

    Butman, Bradford, Valentine, Page C., Middleton, Tammie J., and Danforth, William W., 2007, A GIS library of multibeam data for Massachusetts Bay and the Stellwagen Bank National Marine Sanctuary, offshore of Boston, Massachusetts: Data Series 99, U.S. Geological Survey, Reston, VA.

    Online Links:


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?
    These data were navigated with a differential global positioning system (DGPS) with an assumed accuracy of +/- 10 meters.
  3. How accurate are the heights or depths?
    These data have been corrected for vessel motion (roll, pitch, heave, yaw) and tidal offsets, and referenced to mean lower low water. The manufacturer's reported vertical resolution of the Simrad EM-1000 multibeam echo sounder is 1% of water depth, which is less than 2 m given the depths within the study area (~30 to 184 m). Data were corrected for tidal elevation using the NOAA Boston tide gauge.
  4. Where are the gaps in the data? What is missing?
    This dataset only represents a portion of the 1-m contours present in quadrangle 6 of the Stellwagen Bank survey area. Only the contours necessary to show small features not displayed by 5-m contours are maintained. The 1-m contours produce visual patterns that are helpful to the user by calling attention to low-relief topographic complexity in areas of hummocky relief dominated by gravel deposits and small boulder ridges. These 1-m contours represent a close approximation of seabed microtopography, as the bathymetric data upon which they are based approaches the resolution of the multibeam echo sounder that collected the data. By contrast, 1-m contours are not shown in areas where the seabed is relatively smooth and not dominated by gravel features. In those areas, changes in water depths recorded by the sonar are not resolvable to the extent that they can be contoured at a 1-m interval and produce usable information. Such contours produce incoherent patterns of lines that misrepresent topographic complexity of the seabed.
  5. How consistent are the relationships among the observations, including topology?
    These 1-m contours are not based on a smoothed bathymetry terrain, nor have the contours themselves been smoothed or generalized. For this reason, these 1-m contours could possibly intersect or cross 5-m contours of the same area that are based on a filtered topography.

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: Not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    Page C. Valentine
    U.S. Geological Survey
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov
  2. What's the catalog number I need to order this data set? SIM3341_1m_contours.zip containing SIM3341_1m_contours.shp and the shapefile components as well as FGDC metadata and the browse graphic SIM3341_1m_contours.jpg.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the U.S. Geological Survey, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. 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?
    • Availability in digital form:
      Data format: The WinZip (version 14.0) file contains the data in shapefile format, the browse graphic, and the associated FGDC metadata. in format Shapefile (version ArcGIS 9.3.1) Size: 0.6
      Network links: https://pubs.usgs.gov/sim/3341/data/SIM3341_1m_contours.zip
    • Cost to order the data: None.

  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) shapefile format. The user must software capable of reading this format. The data are available for download in WinZip format.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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