# SEDTHICK_GRD - ESRI ArcRaster grid representing the isopach of Holocene surficial sediment within the inner shelf of Long Bay, South Carolina

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#### 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?

### What does this data set describe?

Title:
  SEDTHICK_GRD - ESRI ArcRaster grid representing the isopach of Holocene surficial sediment within the inner shelf of Long Bay, South Carolina
Abstract:
  In 1999, the USGS, in partnership with the South Carolina Sea Grant Consortium, began a study to investigate processes affecting shoreline change along the northern coast of South Carolina, focusing on the Grand Strand region. Previous work along the U.S. Atlantic coast shows that the structure and composition of older geologic strata located seaward of the coast heavily influences the coastal behavior of areas with limited sediment supply, such as the Grand Strand. By defining this geologic framework and identifying the transport pathways and sinks of sediment, geoscientists are developing conceptual models of the present-day physical processes shaping the South Carolina coast. The primary objectives of this research effort are: 1) to provide a regional synthesis of the shallow geologic framework underlying the coastal upland, shoreface and inner continental shelf, and define its role in coastal evolution and modern beach behavior; 2) to identify and model the physical processes affecting coastal ocean circulation and sediment transport, and to define their role in shaping the modern shoreline; and 3) to identify sediment sources and transport pathways; leading to construction of a regional sediment budget.

1. How should this data set be cited?

   > U.S. Geological Survey, 2007, SEDTHICK_GRD - ESRI ArcRaster grid representing the isopach of Holocene surficial sediment within the inner shelf of Long Bay, South Carolina: Open-File Report 2005-1346, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

   > Online Links:

   > - <http://pubs.usgs.gov/of/2005/1346/ArcGIS/Seismic_srf/sedthick_grd.zip>

   This is part of the following larger work.

   > Baldwin, W.E., Denny, J.F, Schwab, W.C., Gayes, P.T., Morton, R.A., and Driscoll, N.W., 2007, Geologic Framework Studies of South Carolina's Long Bay from Little River Inlet to Winyah Bay, 1999-2003; geospatial data release: Open-File Report 2005-1346, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

   > Online Links:

   > - <http://pubs.usgs.gov/of/2005/1346/>

   Other_Citation_Details: 1 DVD-ROM

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -79.159554
   East_Bounding_Coordinate: -78.515142
   North_Bounding_Coordinate: 33.856092
   South_Bounding_Coordinate: 33.188721

3. What does it look like?

   <http://pubs.usgs.gov/of/2005/1346/images/sedthick_grd.jpg> (JPEG)
     isopach of Holocene surficial sediment thickness within the Long Bay inner shelf

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

   Beginning_Date: 1999
   Ending_Date: 2003
   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 7283 x 5828 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: 17
        Transverse_Mercator:
          Scale_Factor_at_Central_Meridian: 0.999600
          Longitude_of_Central_Meridian: -81.000000
          Latitude_of_Projection_Origin: 0.00000
          False_Easting: 500000.000000
          False_Northing: 0.00000

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 100.00
      Ordinates (y-coordinates) are specified to the nearest 100.00
      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: 0.5
          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: Thickness of Holocene sediment ESRI GRID format.
   Entity_and_Attribute_Detail_Citation: USGS

### 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?

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

   Wayne Baldwin
   U.S. Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   USA

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

### Why was the data set created?

> This data set contains an isopach surface depicting the thickness of Holocene surficial sediment within the inner shelf of Long Bay, offshore of the South Carolina Grand Strand. Chirp seismic data collected with Benthos SIS-1000 and Edgetech SB-512 acquisition systems 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, a digital seismic interpretation package, where the sea floor and underlying transgressive surface (trans_grd) were interpreted and digitized. The isopach between these horizons was exported at every 50th shot as xyz points, and imported to ArcGIS for interpolation into a 10-m raster grid. Each Chirp system has a maximum vertical resolution of ~ 50 cm, so only values greater than 50 cm were used to produce the isopach grid. This does not mean that all no-data values within the grid are representative of no surficial sediment along the inner shelf, but does indicate that these areas likely contain accumulations of less than 50 cm.

### 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: 2003 (process 1 of 3)
     Seismic profiles were interpreted in Landmark software. Each seismic profile was reviewed and acoustic reflectors representing the seafloor and underlying transgressive surface were digitized. An isopach representing Holocene surficial sediment was calculated.

     Person who carried out this activity:

     Wayne Baldwin
     U.S. Geological Survey
     Geologist
     384 Woods Hole Road
     Woods Hole, MA 02543
     USA

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

   Date: 2003 (process 2 of 3)
     The isopach was exported as x,y,z (thickness values) and then imported to ArcGIS as point shapefiles.

     Person who carried out this activity:

     Wayne Baldwin
     U.S. Geological Survey
     Geologist
     384 Woods Hole Road
     Woods Hole, MA 02543
     USA

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

   Date: 2003 (process 3 of 3)
     XYZ point data were used to generate a Triangulated Irregular Network surface using ARCGIS Create TIN and Edit TIN.
     The resulting TIN surface was converted to a floating point grid using ARCGIS TIN to Raster, specifying the natural neighbors method and 100 meter cell size.

     Person who carried out this activity:

     Wayne Baldwin
     U.S. Geological Survey
     Geologist
     384 Woods Hole Road
     Woods Hole, MA 02543
     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?

### 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?

   Seismic navigation was by differential GPS; positional accuracy to less than 10 m

3. How accurate are the heights or depths?

   Seismic data are not corrected for tides. Thickness of Holocene surficial sediments was calculated as the distance between the seafloor and the underlying transgressive surface from interpretation of seismic reflection profiles.

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

   All available interpretations of Holocene surficial sediment are included in this data set.

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

   No additional checks for topological consistency were performed on the data.

### 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:
> >   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)

   Wayne Baldwin
   U.S. Geological Survey
   Geologist
   384 Woods Hole Road
   Woods Hole, MA 02543
   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?

   > Although all data 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 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?

   - Availability in digital form:

     Data format: | no compression applied in format ARCG (version ArcGIS 9.0) ESRI ArcRaster GRID format Size: 162.669
     Network links: | <http://pubs.usgs.gov/of/2005/1346/ArcGIS/Seismic_Srf/sedthick_grd.zip>
     Media you can order: | DVD-ROM (Density 4.75 Gbytes) (format UDF)

   - 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) GRID format. The user must have software capable of importing and processing the data file.

### Who wrote the metadata?

Dates:
  Last modified: 17-Jan-2007
Metadata author:
  Wayne Baldwin
  U.S. Geological Survey
  Geologist
  384 Woods Hole Road
  Woods Hole, MA 02543
  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:
  - Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Generated by `mp` version 2.9.2 on Wed Mar 07 13:50:09 2007