Structure grid of the depth to the Pleistocene surface (Q30), inner shelf and back-barrier from Virginia border to Cape Lookout, North Carolina (q30depth, ESRI binary grid, 200 m cell size, UTM Zone 18N, WGS 84)

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Frequently anticipated questions:


What does this data set describe?

Title:
Structure grid of the depth to the Pleistocene surface (Q30), inner shelf and back-barrier from Virginia border to Cape Lookout, North Carolina (q30depth, ESRI binary grid, 200 m cell size, UTM Zone 18N, WGS 84)
Abstract:
The northeastern North Carolina coastal system, from False Cape, Virginia, to Cape Lookout, North Carolina, has been studied by a cooperative research program that mapped the Quaternary geologic framework of the estuaries, barrier islands, and inner continental shelf. This information provides a basis to understand the linkage between geologic framework, physical processes, and coastal evolution at time scales from storm events to millennia. The study area attracts significant tourism to its parks and beaches, contains a number of coastal communities, and supports a local fishing industry, all of which are impacted by coastal change. Knowledge derived from this research program can be used to mitigate hazards and facilitate effective management of this dynamic coastal system. This regional mapping project produced spatial datasets of high-resolution geophysical (bathymetry, backscatter intensity, and seismic reflection) and sedimentary (core and grab-sample) data. The high-resolution geophysical data were collected during numerous surveys within the back-barrier estuarine system, along the barrier island complex, in the nearshore, and along the inner continental shelf. Sediment cores were taken on the mainland and along the barrier islands, and both cores and grab samples were taken on the inner shelf. Data collection was a collaborative effort between the U.S. Geological Survey (USGS) and several other institutions including East Carolina University (ECU), the North Carolina Geological Survey, and the Virginia Institute of Marine Science (VIMS). The high-resolution geophysical data of the inner continental shelf were collected during six separate surveys conducted between 1999 and 2004 (four USGS surveys north of Cape Hatteras: 1999-045-FA, 2001-005-FA, 2002-012-FA, 2002-013-FA, and two USGS surveys south of Cape Hatteras: 2003-003-FA and 2004-003-FA) and cover more than 2600 square kilometers of the inner shelf. Single-beam bathymetry data were collected north of Cape Hatteras in 1999 using a Furuno fathometer. Swath bathymetry data were collected on all other inner shelf surveys using a SEA, Ltd. SwathPLUS 234-kHz bathymetric sonar. Chirp seismic data as well as sidescan-sonar data were collected with a Teledyne Benthos (Datasonics) SIS-1000 north of Cape Hatteras along with boomer seismic reflection data (cruises 1999-045-FA, 2001-005-FA, 2002-012-FA and 2002-013-FA). An Edgetech 512i was used to collect chirp seismic data south of Cape Hatteras (cruises 2003-003-FA and 2004-003-FA) along with a Klein 3000 sidescan-sonar system. Sediment samples were collected with a Van Veen grab sampler during four of the USGS surveys (1999-045-FA, 2001-005-FA, 2002-013-FA, and 2004-003-FA). Additional sediment core data along the inner shelf are provided from previously published studies. A cooperative study, between the North Carolina Geological Survey and the Minerals Management Service (MMS cores), collected vibracores along the inner continental shelf offshore of Nags Head, Kill Devils Hills and Kitty Hawk, North Carolina in 1996. The U.S. Army Corps of Engineers collected vibracores along the inner shelf offshore of Dare County in August 1995 (NDC cores) and July-August 1995 (SNL cores). These cores are curated by the North Carolina Geological Survey and were used as part of the ground validation process in this study. Nearshore geophysical and core data were collected by the Virginia Institute of Marine Science. The nearshore is defined here as the region between the 10-m isobath and the shoreline. High-resolution bathymetry, backscatter intensity, and chirp seismic data were collected between June 2002 and May 2004. Vibracore samples were collected in May and July 2005. Shallow subsurface geophysical data were acquired along the Outer Banks barrier islands using a ground-penetrating radar (GPR) system. Data were collected by East Carolina University from 2002 to 2005. Rotasonic cores (OBX cores) from five drilling operations were collected from 2002 to 2006 by the North Carolina Geological Survey as part of the cooperative study with the USGS. These cores are distributed throughout the Outer Banks as well as the mainland. The USGS collected seismic data for the Quaternary section within the Albemarle-Pamlico estuarine system between 2001 and 2004 during six surveys (2001-013-FA, 2002-015-FA, 2003-005-FA, 2003-042-FA, 2004-005-FA, and 2004-006-FA). These surveys used Geopulse Boomer and Knudsen Engineering Limited (KEL) 320BR Chirp systems, except cruise 2003-042-FA, which used an Edgetech 424 Chirp and a boomer system. The study area includes Albemarle Sound and selected tributary estuaries such as the South, Pungo, Alligator, and Pasquotank Rivers; Pamlico Sound and trunk estuaries including the Neuse and Pamlico Rivers; and back-barrier sounds including Currituck, Croatan, Roanoke, Core, and Bogue.
  1. How might this data set be cited?
    U.S. Geological Survey, 2013, Structure grid of the depth to the Pleistocene surface (Q30), inner shelf and back-barrier from Virginia border to Cape Lookout, North Carolina (q30depth, ESRI binary grid, 200 m cell size, UTM Zone 18N, WGS 84): Open-File Report 2011-1015, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center.

    Online Links:

    This is part of the following larger work.

    Thieler, E.R., Foster, D.S., Mallinson, D.M., Himmelstoss, E.A., McNinch, J.E., List, J.H., and Hammar-Klose, E.S., 2013, Quaternary Geophysical Framework of the Northeastern North Carolina Coastal System: Open-File Report 2011-1015, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -76.498851
    East_Bounding_Coordinate: -75.305373
    North_Bounding_Coordinate: 36.077914
    South_Bounding_Coordinate: 34.668192
  3. What does it look like?
    http://pubs.usgs.gov/of/2011/1015/data/seismics/interpretation/q30depth.jpg (JPEG)
    Image showing the depth to the Q30 surface
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 07-Oct-1999
    Ending_Date: 09-Jul-2004
    Currentness_Reference:
    ground condition
  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 777 x 535 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: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      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 200.000000
      Ordinates (y-coordinates) are specified to the nearest 200.000000
      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 low water and mean low lower water
      Depth_Resolution: 9999
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    The final q30depth grid was derived with and referenced to the NOAA Coastal Relief Model (CRM), which was based on hydrographic surveys vertical datums are mean low water (89% of the surveys) and mean lower low water (11%) of the surveys) The different vertical datums do not significantly alter the accuracy of the East Coast grids. This is because there is little difference in elevation between mean low water and mean lower low water in the gridding region.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
    The U.S. Geological Survey (USGS) must be referenced as the originator of the dataset in any future products or research derived from these data.
  3. To whom should users address questions about the data?
    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov

Why was the data set created?

This grid represents the surface Q30, a surface within the Pleistocene, derived from analysis of the high-resolution seismic stratigraphy from the offshore and back barrier of North Carolina, from the Virginia border to Cape Lookout. The purpose of this data set is to map Pleistocene surface, Q30, using high-resolution seismic reflection data. These data were collected by the U.S. Geological Survey during twelve separate research cruises beginning in 1999 and ending in 2004. Approximately 13,600 line-km of high-resolution seismic reflection data were collected along the inner continental shelf and back barrier of North Carolina. These data will be used to characterize the subsurface of the seafloor for regional geologic framework investigations.

How was the data set created?

  1. From what previous works were the data drawn?
    Information unavailable from original metadata. (source 1 of 1)
    The source information was incomplete and had to be modified to meet the standard. Assumed to be USGS., unknown, Information unavailable from original metadata..

    Type_of_Source_Media: Information unavailable from original metadata.
    Source_Contribution:
    1999-045-FA: October 7-27, 1999 2001-005-FA: July 1-18, 2001 2001-013-FA: August 1-17, 2001 2002-012-FA: June 20 - July 5, 2002 2002-013-FA: July 7-20, 2002 2002-015-FA: July 29 - August 16, 2002 2003-003-FA: June 17 - July 1, 2003 2003-005-FA: July 20 - August 10, 2003 2003-043-FA: July 22 - August 10, 2003 2004-003-FA: June 16 - July 9, 2004 2004-005-FA: July 18 - August 07, 2004 2004-006-FA: July 18-31, 2004
  2. How were the data generated, processed, and modified?
    Date: unknown (process 1 of 16)
    For boomer data: Back-barrier (2001-013-FA, 2002-015-FA, 2003-005-FA, 2003-042-FA, 2004-005-FA) and inner shelf (1999-045-FA, 2001-005-FA, 2002-012-FA, 2002-013-FA) surveys were acquired using a Triton-Elics Delph Seismic acquisition system. The data were recorded in 16-bit integer standard SEG-Y format. DGPS navigation data were input in realtime to the acquisition system through HYPACK navigation software. The data are stored in the SEG-Y trace headers as UTM Zone 18 coordinates (meters). Back-barrier survey 2004-006-FA was acquired with a Delph Seismic Plus acquisition system with geographic coordinates in the SEG-Y header. For chirp data: Inner shelf chirp (Edgetech 512i) surveys 2003-003-FA and 2004-003-FA were acquired with an Edgetech JStar acquisition system with geographic coordinates in Edgetech JSF header. All JSF files were then converted to SEG-Y format. This process step and all subsequent steps were performed by the same person: David S. Foster. Person who carried out this activity:
    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov
    Date: unknown (process 2 of 16)
    Unique UTM coordinates and associated shot point number were extracted from each SEG-Y header using Seismic Unix. Output was formatted with an AWK script for all surveys except 2003-003-FA and 2004-003-FA and 2004-006-FA. For these surveys geographic coordinates and associated shot point number were extracted from the SEG-Y header using Seismic Unix. Geographic coordinates were projected into UTM coordinates using Proj 4.0, then formatted for output with an AWK script.
    Date: unknown (process 3 of 16)
    Each SEG-Y data file was processed, filtered, and gain enhanced using Seismic Unix and SIOSIES and Promax software.
    Date: unknown (process 4 of 16)
    The UTM coordinate pairs and two-way travel time attribute for the horizon data were imported into Landmark Graphics seismic interpretation software SeisWorks R3000 (field activities 1999-045-FA, 2001-005-FA, 2002-012-FA, 2002-013-FA) and SeisVision R2003 (field activities 2003-003-FA and 2004-003-FA), and Kingdom Suite (2001-013-FA, 2002-015-FA, 2003-042-FA, and 2004-005-FA. The data was exported as an ASCII X, Y, and Z (two-way travel time) file.
    Date: unknown (process 5 of 16)
    The ASCII data were converted to EarthVision 7.0 (Dynamic Graphics, Inc.) scattered data format with an AWK script.
    Date: unknown (process 6 of 16)
    The scattered data were gridded with EarthVision 7.0. The gridded surface of Q30 was edited using the the graphic editor. Large areas of the grid that represented interpolation over NODATA areas were set to null values.
    Date: unknown (process 7 of 16)
    A difference grid was created with a 200 meter grid cell spacing. A modified version of the NOAA coastal relief model was converted to a two-way travel time grid using a velocity of 1700 m/s and was used as a base, and the difference was calculated between the base and the two-way travel time grid of depth to Q30. All grid calculations were done with EarthVision 7.0 Formula Processor.
    Date: unknown (process 8 of 16)
    The isochron grid was converted to thickness in meters using a velocity of 1700 m/s with EarthVision 7.0 Formula Processor.
    Date: unknown (process 9 of 16)
    The isopach thickness of the seafloor to the top of Q30 was added to the modified NOAA coastal relief model. The result was saved as depth to the top of Q30 with EarthVision 7.0 Formula Processor.
    Date: unknown (process 10 of 16)
    The depth to the Pleistocene surface, Q30, was exported from EarthVision 7.0 as an ASCII x, y, and z file.
    Date: unknown (process 11 of 16)
    The X, Y, and Z ASCII file was converted to a Arc format grid using xyz2grid.aml in Arc/Info workstation 9.1.
    Date: 12-Apr-2011 (process 12 of 16)
    The raster grid values were multiplied by -1 to convert positive depths to negative using ArcToolbox (9.2) > 3D Analyst Tools > Raster Math > Times. Person who carried out this activity:
    Emily Himmelstoss
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2262 (voice)
    508-457-2310 (FAX)
    ehimmelstoss@usgs.gov
    Date: 15-Jun-2016 (process 13 of 16)
    Edits to the metadata were made to fix any errors that MP v 2.9.32 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.). The link to the data catalog was fixed. The source information was incomplete and had to be modified to meet the standard. In the case of the depth resolution, the value of 9999 was entered to indicate that the original metadata did not contain the required information. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. 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 Rd.
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 14 of 16)
    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 15 of 16)
    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 16 of 16)
    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?
    Grid values are floating point format.
  2. How accurate are the geographic locations?
    All boomer seismic lines from cruises 20010-13-FA, 2002-015-FA, 2003-005-FA, 2004-005-FA, and 2004-006-FA were positioned using Differential GPS (DGPS), with accuracy less than 5 meters. The position (layback) of the seismic source and receiver were not factored in the shotpoint position. The shotpoint position is relative to the position of the DGPS antenna, not the seismic source. Accuracy is assumed to be approximately 10 meters. For cruises 1999-045-FA, 2001-045-FA, 2002-012-FA, 2002-013-FA Teledyne Benthos (Datasonics) SIS-1000 chirp lines were positioned using Differential GPS (DGPS), with accuracy less than 5 meters. The position (layback) were factored in the shotpoint position. Uncertainty of layback corrections likely degraded accuracy. The shotpoint position is relative to the DGPS antenna. For cruises 2003-003-FA and 2004-003-FA a GPS receiver was mounted on the Edgetech 512i Chirp that was towed aft of the ship, one meter below the water surface and positioned without differential corrections resulting in about 30 meters accuracy. Therefore total uncertainty is approximately 30 meters.
  3. How accurate are the heights or depths?
    Time zero of two-way travel time is relative to local sea surface. No corrections for sea level or tide variation (which is less than 2 meters offshore and less than one meter in Pamlico and Albemarle Sounds) are applied. Vertical resolution of less than one meter of the seismic reflection systems are less than the tidal ranges. Vertical accuracy of the final derived grid is also a function of the vertical accuracy of the NOAA Coastal Relief Model (CRM).
  4. Where are the gaps in the data? What is missing?
    All of the original boomer and chirp seismic reflection data were used from U.S. Geological Survey inner shelf and back-barrier cruises 1999-045-FA, 2001-005-FA, 2001-013-FA, 2002-012-FA, 2002-013-FA, 2002-015-FA, 2003-003-FA, 2003-005-FA, 2003-042-FA, 2004-003-FA, 2004-005-FA, and 2004-006-FA.
  5. How consistent are the relationships among the observations, including topology?
    This grid represents interpolated data; processed to account for gaps that occurred along-track and between adjacent survey lines.

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 as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@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 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?

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
David S. Foster
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2271 (voice)
(508) 457-2310 (FAX)
dfoster@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/ofr2011-1015/q30depth.faq.html>
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