Utelev: Elevation of the Holocene transgressive unconformity beneath the Massachusetts inner continental shelf between Nahant and Northern Cape Cod Bay (Esri binary grid; UTM, Zone 19N, WGS 84)

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Frequently anticipated questions:

What does this data set describe?

Title:
Utelev: Elevation of the Holocene transgressive unconformity beneath the Massachusetts inner continental shelf between Nahant and Northern Cape Cod Bay (Esri binary grid; UTM, Zone 19N, WGS 84)
Abstract:
These data are qualitatively derived interpretive polygon shapefiles and selected source raster data defining surficial geology, sediment type and distribution, and physiographic zones of the sea floor from Nahant to Northern Cape Cod Bay. Much of the geophysical data used to create the interpretive layers were collected under a cooperative agreement among the Massachusetts Office of Coastal Zone Management (CZM), the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, the National Oceanic and Atmospheric Administration (NOAA), and the U.S. Army Corps of Engineers (USACE). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of seafloor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes because of natural or human effects. The project is focused on the inshore waters of coastal Massachusetts. Data collected during the mapping cooperative involving the USGS have been released in a series of USGS Open-File Reports (<http://woodshole.er.usgs.gov/project-pages/coastal_mass/html/current_map.html>). The interpretations released in this study are for an area extending from the southern tip of Nahant to Northern Cape Cod Bay, Massachusetts. A combination of geophysical and sample data including high resolution bathymetry and lidar, acoustic-backscatter intensity, seismic-reflection profiles, bottom photographs, and sediment samples are used to create the data interpretations. Most of the nearshore geophysical and sample data (including the bottom photographs) were collected during several cruises between 2000 and 2008. More information about the cruises and the data collected can be found at the Geologic Mapping of the Seafloor Offshore of Massachusetts Web page: <http://woodshole.er.usgs.gov/project-pages/coastal_mass/>.
  1. How should this data set be cited?

    Baldwin, Wayne, 2013, Utelev: Elevation of the Holocene transgressive unconformity beneath the Massachusetts inner continental shelf between Nahant and Northern Cape Cod Bay (Esri binary grid; UTM, Zone 19N, WGS 84): Open-File Report 2012-1157, 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.

    Pendleton, E.A., Baldwin, W.E., Barnhardt., W.A., Ackerman, S.D., Foster, D.S., Andrews, B.D., and Schwab, W.C., 2013, Shallow Geology, Seafloor Texture, and Physiographic Zones of the Inner Continental Shelf from Nahant to Northern Cape Cod Bay, Massachusetts: Open-File Report 2012-1157, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -70.828722
    East_Bounding_Coordinate: -70.154249
    North_Bounding_Coordinate: 42.349106
    South_Bounding_Coordinate: 41.924520

  3. What does it look like?

    <http://pubs.usgs.gov/of/2012/1157/GIS_catalog/Stratigraphy/Ut/surface/Utelev_browse.png> (png)
    browse image of Esri grid representing Ut surface

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

    Beginning_Date: 04-Aug-2006
    Ending_Date: 07-May-2008
    Currentness_Reference: ground condition of data used to derive the interpretation

  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 924 x 1099 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:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
      Depth_System_Definition:
      Depth_Datum_Name: North American Vertical Datum of 1988
      Depth_Resolution: 0.001
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates

  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)

  2. Who also contributed to the data set?

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

    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    U.S. Geological Survey
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

Why was the data set created?

This data set contains a grid representing the elevation (NAVD88) of the Holocene transgressive unconformity (Ut) beneath the Massachusetts inner shelf between Nahant and northern Cape Cod Bay. These data are useful for assessing relations between geologic framework, sea-bed morphology, and sediment textural trends.

How was the data set created?

  1. From what previous works were the data drawn?

    Barnhardt and others, 2010 (source 1 of 2)
    Barnhardt, Walter A., Ackerman, Seth D., Andrews, Brian D., and Baldwin, Wayne E., 2010, Geophysical and Sampling Data from the Inner Continental Shelf: Duxbury to Hull, Massachusetts.: Open-File Report 2009-1072, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    Shallow geologic framework and surficial geology were interpreted from approximately 1920 trackline kilometers of CHIRP seismic-reflection profiles that were collected during two separate U.S. Geological Survey field activities (2006-012-FA and 2007-001-FA) . Final, post-processed profiles were used to make the interpretations. Thorough descriptions of acquisition and processing parameters for each survey are provided by Barnhardt and others (2010) in the methods section and seismic-reflection metadata.

    Andrews and others, 2010 (source 2 of 2)
    Andrews, Brian D., Ackerman, Seth D., Baldwin, Wayne E., and Barnhardt, Walter A., 2010, Geophysical and Sampling Data from the Inner Continental Shelf: Northern Cape Cod Bay, Massachusetts: Open-File Report 2010-1006, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    Shallow geologic framework and surficial geology were interpreted from approximately 3270 trackline kilometers of CHIRP seismic-reflection profiles that were collected during two separate U.S. Geological Survey field activities (2007-002-FA and 2008-002-FA). Final, post-processed profiles were used to make the interpretations. Thorough descriptions of acquisition and processing parameters for each survey are provided by Andrews and others (2010) in methods sections and seismic-reflection metadata.

  2. How were the data generated, processed, and modified?

    Date: 2012 (process 1 of 3)
    CHIRP seismic reflection data were interpreted using Landmark SeisWorks 2D (R5000) seismic interpretation software. Interpretation consisted of identifying and digitizing erosional unconformites defining the boundaries between Holocene, Pleistocene, and pre-Quaternary seismic units, and digitizing the extent over which each of the defined sub-surface seismic units crops out on the seafloor. An isochron representing the two-way travel time between the Holocene transgressive unconformity and seafloor horizons was computed, then sampled at a 30-meter along track interval and exported from SeisWorks as ASCII text. Awk (no version) was used to convert two-way travel times to thicknesses in meters using a constant seismic velocity of 1500 m/s.

    Person who carried out this activity:

    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    U.S. Geological Survey
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

    Date: 2012 (process 2 of 3)
    Mass points representing the isopach computed in the previous step were imported into ArcMap (9.3.1) as point features (easting, northing, thickness) using the 'Add XY data' function, then saved as a point shapefile. The new point shapefile was used as the sole input for the ArcMap (9.3.1) Spatial Analyst tool 'Topo to Raster' to create an interpolated grid of the isopach with a 50 meter cell size. A polygon shapefile traced around the input mass-points was used to clip the isochron grid to the limits of the interpreted area using the ArcMap (9.3.1) Spatial Analyst tool 'Extract by Mask'.

    Person who carried out this activity:

    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    U.S. Geological Survey
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

    Date: 2012 (process 3 of 3)
    The ArcMap (9.3.1) Spatial Analyst 'Raster Calculator' was used to set grid cells with thickness values less than 0.5 meters to null, then add the isopach grid to the regional bathymetry DEM ('navd_bath_30m) to produce a new grid representing the NAVD88 elevation of the transgressive unconformity.

    Person who carried out this activity:

    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    U.S. Geological Survey
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

  3. What similar or related data should the user be aware of?

    Oldale, Robert N., and Bick, Jennifer, 1987, Maps and Seismic Profiles Showing Geology of the Inner Continental Shelf, Massachusetts Bay, Massachusetts: U.S. Geological Survey Miscellaneous Field Studies Map MF-1923, U.S. Geological Survey, Woods Hole, MA.

    Other_Citation_Details: 4 sheets
    Oldale, Robert N., and O'Hara, Charles J., 1990, Maps Showing the Geology of the Inner Continental Shelf, Cape Cod Bay, Massachusetts: U.S. Geological Survey Miscellaneous Field Studies Map MF-2118, U.S. Geological Survey, Woods Hole, MA.

    Online Links:

    Other_Citation_Details: 4 sheets

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?

    Navigational accuracy of the seismic-reflection data used for this interpretation was assumed to be ± 10 to 20 meters. Refer to seismic trackline metadata in Barnhardt and others (2010; <http://pubs.usgs.gov/of/2009/1072/GIS/hyperlink_images/seisimage/DH_SeismicProfiles_metadata.html>) and Andrews and others (2010; <http://pubs.usgs.gov/of/2010/1006/GIS/hyperlink_images/seisimage/CCB_seismicprofiles_metadata.html>) for specific seismic data aqcuisition parameters and accuracy reports.

  3. How accurate are the heights or depths?

    The nominal resolution of the CHIRP seismic-reflection systems is 0.5 meter. The vertical resolution of the bathymetric grid used in generating the transgressive unconformity elevation is 0.5 m (referenced to NAVD88). Overall vertical accuracy is assumed to be +/- 0.5 meter.

  4. Where are the gaps in the data? What is missing?

    All CHIRP seismic reflection data collected during USGS Woods Hole Coastal and Marine Science Center field activities 2006-012-FA, 2007-001-FA, 2007-002-FA, and 2008-002-FA were used to interpret stratigraphic units and unconformities.

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

    CHIRP seismic-reflection data used to interpret regional geologic framework were collected during USGS Woods Hole Coastal and Marine Science Center field activities 2006-012-FA, 2007-001-FA, 2007-002-FA, and 2008-002-FA. The geologic framework interpretations in this report were correlated with previous interpretations by Oldale and Bick (1987) and Oldale and O'Hara (1990) for Massachusetts and Cape Cod bays, respectively.

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:
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. Additionally, there are limitations associated with eologic mapping interpretations. Because of the scale and line spacing of the source seismic profiles, not all changes in seafloor geology are captured. Horizons are inferred between seismic lines, and unit exents and thicknesses should be considered an approximation of the location of a change in geology. Further, a constant seismic velocity of 1,500 m/s was assumed for all profiles in all sediment types, which may result in inaccurate depths of stratigraphic units.

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

    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    U.S. Geological Survey
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

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

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Neither the U.S. Government, the Department of the Interior, nor the USGS, 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 U.S. Geological Survey 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?

    The grid contained in the ZIP file is available as an Esri binary grid. To utilize this data, the user must have a GIS software package capable of reading an Esri binary grid.

Who wrote the metadata?

Dates:
Last modified: 02-Jul-2013
Metadata author:
Wayne E. Baldwin
U.S. Geological Survey
Geologist
U.S. Geological Survey
Woods Hole, MA 02543-1598
USA

508-548-8700 x2226 (voice)
508-457-2310 (FAX)
wbaldwin@usgs.gov

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

Generated by mp version 2.9.21 on Tue Jul 02 13:40:58 2013