Stratigraphic Framework Maps of the inner-continental shelf within the New York Bight: Gridded Elevation of coastal-plain Unconformity

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

Title:

Stratigraphic Framework Maps of the inner-continental shelf within the New York Bight: Gridded Elevation of coastal-plain Unconformity

Abstract:

Mapping the elevation of the coastal-plain unconformity is useful for delineating the geologic framework of the New York Bight inner-continental shelf. This in turn aids in understanding the stratigraphic evolution of the inner-continental shelf, the regional sediment transport system, and the influence of the inner-shelf framework on coastal processes. The grid showing structure of the coastal-plain unconformity is an important factor in the framework of the coastal region.

1. How should this data set be cited?

   Denny, Jane F. , and Foster, David S. , 20020201, Stratigraphic Framework Maps of the inner-continental shelf within the New York Bight: Gridded Elevation of coastal-plain Unconformity: US Geological Survey, Woods Hole, MA.

   Online Links:

   • http:/woodshole.er.usgs.gov/project-pages/newyork/

   This is part of the following larger work.

   Schwab, William C., Denny, Jane F., Foster, David S., Lotto, Linda L., Allison, Mead A., Uchupi, Elazar, Swift, B. Ann, Danforth, William W., Thieler, Robert E., and Butman, Bradford, 2002, High-Resolution Quaternary seismic stratigraphy of the New York Bight Continental Shelf: Open-File Report OFR02-152, U.S. Geological Survey, Woods Hole, MA.

    

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -74.06

   East_Bounding_Coordinate: -71.8000

   North_Bounding_Coordinate: 41.2322

   South_Bounding_Coordinate: 40.15

3. What does it look like?

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

   Beginning_Date: May-1995

   Ending_Date: Oct-1998

   Currentness_Reference: Field Work

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 631 x 971, 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: 18

      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.999600

      Longitude_of_Central_Meridian: -075.000000

      Latitude_of_Projection_Origin: +00.000000

      False_Easting: 500000

      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 200
      Ordinates (y-coordinates) are specified to the nearest 200
      Planar coordinates are specified in Meters

      The horizontal datum used is WGS84.
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.0000000.
      The flattening of the ellipsoid used is 1/298.26.
      

      Vertical_Coordinate_System_Definition:

      Altitude_System_Definition:

      Altitude_Datum_Name: North American Vertical Datum of 1988

      Altitude_Resolution: 1

      Altitude_Distance_Units: Meters

      Altitude_Encoding_Method:

      Explicit elevation coordinate included with horizontal coordinates

      Depth_System_Definition:

      Depth_Datum_Name: Mean sea level

      Depth_Resolution: 0.1

      Depth_Distance_Units: Meters

      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates

7. How does the data set describe geographic features?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Jane F. Denny
   • David S. Foster
2. Who also contributed to the data set?

   Prepared by the US Geological Survey in cooperation with the US Army Corps of Engineers

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

   US Geological Survey
   c/o Jane F. Denny
   Geologist, Seafloor Mapping Group
   384 Woods Hole Road
   Woods Hole, MA 012543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Hours_of_Service: Monday-Friday, 8am-5pm, Eastern Standard Time

In 1995, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers (USACE), began a program to generate reconnaissance maps of the sea floor offshore of the New York - New Jersey metropolitan area and within the southern Long Island nearshoe area. Our methods include high-resolution sidescan sonar and subbottom profiling techniques, along with surface grab and vibracore sampling to verify the geophysical interpretations. The goal of the investigation is to provide a regional synthesis of the sea-floor environment, to determine regional-scale availability of sand as a resource for beach nourishment programs, and to investigate the role that inner-shelf morphology and geologic framework have in the evolution of the coastal region within the New York Bight Apex and southern Long Island. Maps derived from interpretation of the subbottom profiles show information on the geometry and distribution of the Quaternary sediments and the underlying coastal-plain unconformity. This seismic stratigraphy yields a regional framework on which explanations of present (and past) sediment movement, dispersal, and erosion processes are based.

1. From what previous works were the data drawn?

   Coastal Relief Model (source 1 of 3)

   NOAA, 19990000, Exposing the U.S. Coastal Zone: EOS, Transactions of the American Geophysical Union vol. 80, no. 4, NOAA, Boulder, CO.

   Online Links:

   • <http://www.ngdc.noaa.gov/mgg/coastal/coastal.html>

   Type_of_Source_Media: DVD-ROM

   Source_Contribution:

   The NOAA Coastal Relief Model was used to reference (topograhic base) subbottom surfaces to mean sea level

   Onshore Well Logs (source 2 of 3)

   Lotto, Linda, 20000000, Seismic Stratigraphy and Quaternary Evolution of the New York Bight Inner Continental Shelf: Texas A&M University unpublished MS Thesis, Texas A&M University, College Station, TX.

   Type_of_Source_Media: paper

   Source_Contribution:

   Well logs from the New York State Department of Conservation and the USGS were analyzed by Lotto (2000) to determine the elevation of the coastal-plain unconformity on land.

   Gridded elevation of the coastal-plain Unconformity along nearshore off southern Long Island (Fire Island - Montauk) (source 3 of 3)

   Foster, David S. , 1999, Stratigraphic Framework Maps of the Nearshore Area of Southern Long Island, New York: Gridded Elevation of coastal-plain Unconformity: U.S. Geological Survey USGS Open-File Report, U.S. Geological Survey, Woods Hole, MA.

   Online Links:

   • <http://woodshole.er.usgs.gov/epubs/openfiles/ofr99-559/>

   Type_of_Source_Media: paper products

   Source_Contribution:

   These data were combined with the grid of the elevation of the Coastal plain unconformity within the New York Bight (west of the Long Island area) in order to generate a composite grid of the elevation of the Coastal plain unconformity within the inner-continental shelf of the New York Bight.

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

   Date: 2000 (process 1 of 9)

   Processed SEG-Y seismic data and associated shot navigation data acquired within the New York Bight, were loaded into Landmark Seisworks interpretation software. The coastal-plain unconformity was digitized along with the seafloor reflector. The difference in two-way travel time between horizons was calculated and converted to meters using an assumed velocity of 1630 m/s. This represents the nearshore Quaternary sediment thickness. These data were exported from seisworks to an ASCII format file.

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 2000 (process 2 of 9)

   The ASCII point data were imported to Dynamic Graphics Inc., EarthVision surface modelling software. The points representing Quaternary sediment thickness were gridded with a 200 meter grid cell size. Bathymetric data that were collected the same time as the seismic profile data were gridded using a 150 m grid cell size. The Quaternary sediment thickness grid was addded to the bathymetric grid to yield a grid for the nearshore elevation of the Coastal plain unconformity reference to mean sea level.

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 2000 (process 3 of 9)

   The exported ASCII file from the nearshore coastal-plain unconformity elevation was combined with onshore well elevations of the coastal-plain unconformity.

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 2000 (process 4 of 9)

   The total onshore and nearshore coastal-plain unconformity elevations were imported into EarthVision. The data were gridded at a 200 m grid spacing.

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 01-Nov-2001 (process 5 of 9)

   The resultant grid represented the onshore and offshore elevation of coastal-plain unconformity for all of Long Island and the inner-shelf region from the New Jersey coast to Long Beach. A grid of the elevation of the Coastal plain unconformity along the nearshore of southern Long Island was generated in a study published in 1999 (USGS Open-File Report, 00-243). To generate a composite grid of the elevation of the Coastal plain unconformity, the two grids were merged within EarthVision, using the union command. Minor edits were required at the boundaries of the union.

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 2000 (process 6 of 9)

   The exported ASCII coastal-plain unconformity elevation grid file from EarthVision was edited to create an ASCII grid file suitable for import to ArcView software. The order of rows were flipped, so that the file begins with the lower row, left column and ends with the upper row right column. An ArcView header that descibes the lower left origin of the grid, the grid cell size, the number of rows and columns, and the null value used (-9999).

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 2000 (process 7 of 9)

   The edited ASCII grid file was imported into ArcView software with the Spatial Analyst extension. The file was saved as an ArcInfo raster grid format.

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 2000 (process 8 of 9)

   Contour data were generated from the coastal-plain Unconformity Gridded data at a 5 meter contour interval within EarthVision. These data were exported and converted to an ESRI generate format. The contour interval associated with each contour was saved as an ASCII file and read into ArcView in table format. The generate file was converted to a vector shapefile. The table and attritube table of the contour shapefile were joined based on unique contour IDs. The attribute table was then editted to include the associated contour value with each contour line, and the join was removed. The contour data are stored in the Geographic Coordinate System (decimal degrees, WGS84 Ellipsoid).

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

   Date: 2000 (process 9 of 9)

   The resultant grid and contour data were clipped to the 1995 and 1996 survey extents and all of Long Island using GRIDCLIP script within ArcView 3.2.

   Person who carried out this activity:
   

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

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

1. How well have the observations been checked?

   These data are derived from 2D seismic reflection profiles that are spaced approximately 1.3 km apart in the cross track-direction. Shore perpendicular track lines were spaced about 3-4 km apart. Along track samples of the seismic profiles are approximately 1 meter assuming a ship speed of 2 meters/second. The data were downsampled in the along-track direction at an interval of about 30 meters. The horizontal resolution of the gridded data are constrained by the grid cell size of 100 meters. Horizontal interpolation is inherent in the gridding process.

2. How accurate are the geographic locations?

   DGPS is assumed to be accurate within 1-2 meters. Standard GPS is assumed accurate within 5-10 meters. 99% of the positional data is DGPS. Unless noted, all GPS/DGPS data is referenced to WGS84 (NAD83). The horizontal positioning did not account for source and receiver offsets and offset the GPS antennae and the boomer source and streamer. It is estimated that these offsets could lead to inaccuracies of about 30 m. Because the elevation of the coastal-plain unconformity was calculated by adding Quaternary thickness to a coastal elevation model //www.ngdc.noaa.gov/mgg/coastal/coastal.html), the horizontal accuracy is constrained by the reference to USGS 3-arc-second topographic data (nominal resolution of 90 meters). Offshore hydrographic positioning that is estimated to be 30 m or better closer to shore. Onshore well locations were digitized from paper maps (Sutter and others, 1949).

3. How accurate are the heights or depths?

   Vertical positioning accuracy of the offshore data is based on the seafloor reference used. coastal-plain elevation in the offshore was determined by adding Quaternary sediment thickness (derived from two-way travel time between the coastal-plain unconformity and the seafloor using an acoustic velocity of 1630 m/s) to a topographic and bathymetric elevation model //www.ngdc.nooa.gov/mgg/coastal/coastal.html). This costal elevation model is referenced to USGS 3-arc-second DEM data that has a vertical accuracy of 1 meter and NOS hydrographic data that has an accuracy of 1/10 of a meter. The entire model is referenced to mean sea level. Onshore well elevations were taken from well logs descriptions (Sutter and others, 1949).

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

   The gridded data are limited by horizontal resolution of the grid cell size and spatial distribution of the original point data. Higher resolution data acquisition will likely result in a more detailed representation of sediment thickness. The data also represent a time interval of the data acquisition. Attributes of elevation of the coastal-plain unconformity change very little over time.

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

   The gridded data were checked for consistency by plotting the point data over the the grid and comparing point values with grid cell values.

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)

   Jane F. Denny
   US Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA
   

   508-457-2311 (voice)
   508-457-2310 (FAX)
   jdenny@usgs.gov
   

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

   cpof_grd

3. What legal disclaimers am I supposed to read?

   Altough this data set and its lineage have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or it's 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 items. Users must assume responsibility for the proper use of this data. This data should not be used at resolutions for which it is not intended. This data has no been reviewed for conformity with US Geological Survey editorial standards, or the North American Strigraphic code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

4. How can I download or order the data?

Dates:

Last modified: 19-Jan-2002
Last Reviewed: 2002

Metadata author:

Jane F. Denny
US Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA 02543
USA

508-457-2311 (voice)
508-457-2310 (FAX)
jdenny@usgs.gov

Metadata standard:

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