Geologic outcrop and subcrop type within the inner shelf of Long Bay (Polygon)

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Frequently-anticipated questions:

What does this data set describe?

Title:
Geologic outcrop and subcrop type within the inner shelf of Long Bay (Polygon)
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, Geologic outcrop and subcrop type within the inner shelf of Long Bay (Polygon): Open-File 2005-1346.

    Online Links:

    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:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -79.158289
    East_Bounding_Coordinate: -78.517005
    North_Bounding_Coordinate: 33.845955
    South_Bounding_Coordinate: 33.198465

  3. What does it look like?

    <http://pubs.usgs.gov/of/2005/1346/images/surf_geol.jpg> (JPEG)
    Image showing the type of geologic outcrop and subcrop within inner shelf of Long Bay

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

    Calendar_Date: 2007
    Currentness_Reference: publication date

  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):

      • G-polygon (1536)

    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 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.

  7. How does the data set describe geographic features?

    surf_geol
    ESRI polygon shapefile (Source: ESRI)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    Id
    Internal ID (Source: USGS)

    Range of values
    Minimum:0
    Maximum:2487
    Units:integer count
    Resolution:1

    geol_type
    Age and type of geologic unit present in outcrop at the seafloor, or subcrop near the surface (Source: USGS)

    ValueDefinition
    Cretaceous - rocks of the Pee Dee formationgeologic type (age classification)
    Holocene - surficial sedimentary depositsgeologic type (age classification)
    Quaternary - Paleochannel Fillgeologic type (age classification)
    Tertiary - rocks of the Black Mingo groupgeologic type (age classification)

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
    384 Woods Hole Road
    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 polygons that identify the geologic unit type present in outcrop or subcrop along the Long Bay inner shelf. Polygon areas are based upon digital interpretations of Chirp seismic reflection data and coastal plain boreholes. A polygon outlining the inner shelf study area was erased (ArcGIS Analysis toolbox)in iterations using polygons outlining gridded surfaces of Holocene surficial sediment (sedthick_grd)and paleochannel unconformities (paleoch_grd). Outside of the area covered by the Holocene surficial sediment grid, seismic data indicate surficial sediment cover of < 50 cm. In these areas, paleochannel fills, Cretaceous, and Tertiary units are interpreted to crop out at the sea floor, or subcrop near the surface.

How was the data set created?

  1. From what previous works were the data drawn?

    sedthick_grd, v1.0, 2006 (source 1 of 2)
    U.S. Geological Survey, 2007, SEDTHICK_GRD - ESRI ArcRaster representing the isopach of Holocene surficial sediment within the inner shelf of Long Bay, South Carolina: Open-File 225-1346, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    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:

    Type_of_Source_Media: DVD-ROM
    Source_Contribution:
    This data set contains polygons that identify the geologic unit type present in outcrop or subcrop along the Long Bay inner shelf. Polygon areas are based upon digital interpretations of Chirp seismic reflection data and coastal plain boreholes. A polygon outlining the inner shelf study area was erased (ArcGIS Analysis toolbox) in iterations using polygons outlining gridded surfaces of Holocene surficial sediment (sedthick_grd) and paleochannel unconformities (paleoch_grd). Outside of the area covered by the Holocene surficial sediment grid, seismic data indicate surficial sediment cover of < 50 cm. In these areas, paleochannel fills, Cretaceous, and Tertiary units are interpreted to crop out at the sea floor, or subcrop near the surface.

    palech_grd, v1.0, 2006 (source 2 of 2)
    U.S. Geological Survey, 2007, PALEOCH_GRD - ESRI ArcRaster representing the elevations of paleochannel unconformities underlying the inner shelf of Long Bay, South Carolina: Open-File 2005-1346, U.S. Geological Survey, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    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:

    Type_of_Source_Media: DVD-ROM
    Source_Contribution:
    This data set contains polygons that identify the geologic unit type present in outcrop or subcrop along the Long Bay inner shelf. Polygon areas are based upon digital interpretations of Chirp seismic reflection data and coastal plain boreholes. A polygon outlining the inner shelf study area was erased (ArcGIS Analysis toolbox) in iterations using polygons outlining gridded surfaces of Holocene surficial sediment (sedthick_grd) and paleochannel unconformities (paleoch_grd). Outside of the area covered by the Holocene surficial sediment grid, seismic data indicate surficial sediment cover of < 50 cm. In these areas, paleochannel fills, Cretaceous, and Tertiary units are interpreted to crop out at the sea floor, or subcrop near the surface.

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

    Date: 2003 (process 1 of 4)
    Polygon shapefiles outlining the gridded surface areas of Holocene surficial sediments (sedthick_grd) and paleochannel unconformities (paleoch_grd) were generated.

    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

    Data sources used in this process:
    • sedthick_grd, v1.0, 2006
    • paleoch_grd, v1.0, 2006

    Data sources produced in this process:

    • surf_geol.shp

    Date: 2003 (process 2 of 4)
    The erase function, within the ArcGIS Analysis toolbox, was used in iterations to reduce a polygon outlining the entire inner shelf study area. First, the polygon outlining Holocene surficial sediment was used, and then the polygon outlining paleochannel fills.

    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: 2007 (process 3 of 4)
    The resulting polygon of the study area (without areas coincident with the Holocene surficial sediment and paleochannel surfaces) was then split, using an arc that was projected from the intersection of the Cretaceous/Tertiary boundary with the coast to the seaward edge of the study area.

    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: 2007 (process 4 of 4)
    Each polygon shapefile was classified by the interpreted geologic type and the four were merged back to a single polygon shape file.

    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?

    These data were interpretted from seismic-reflection and sample data at a regional scale of 1:75,000.

  2. How accurate are the geographic locations?

    Interpretations are derived from seismic-reflection and sample data at a regional scale of 1:75000.

  3. How accurate are the heights or depths?

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

    All interpretations of seafloor geologic type are present 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:
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?

  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 have ArcGIS or ArcView 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing the data. A free data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 23-Jan-2007
Metadata author:
Wayne Baldwin
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA 02543-1598
USA

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

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

Generated by mp version 2.9.2 on Wed Mar 07 15:27:08 2007