Folds -- Point San Luis map area [sheet 5]

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Frequently anticipated questions:


What does this data set describe?

Title: Folds -- Point San Luis map area [sheet 5]
Abstract:
This part of SIM 3327 presents data for folds on the offshore geologic and geomorphic map of the Point San Luis map area, in the vicinity of Pismo Beach, California. The vector data file is included in "Folds_PointSanLuis.zip," which is accessible from <https://pubs.usgs.gov/sim/3327/data/sim3327_data_catalog.html>.
Faults shown on these maps are near-surface (upper about 200 m) structures that are mapped primarily on the basis of interpretation of minisparker seismic-reflection data (tracklines shown in fig. 2 on sheets 2, 4, 6; see also, Sliter and others, 2009). These fault and fold interpretations were further modified on the basis of multibeam imagery and magnetic data; these laterally continuous datasets allow for more accurate interpolation of structures between the seismic-reflection profiles. However, we do not infer fault activity from these data, as we have no direct age data for surficial sediments.
Offshore faults are symbolized as follows: a solid line is used where the location is certain; a dashed line, where the location is inferred; and a dotted line, where the location is concealed. In addition, queries are added where the existence of a feature is questionable. A fault or fold is mapped as inferred when its location is determined by interpolating between seismic-reflection profiles, as well as in bedrock outcrops where a lineament exists in the multibeam imagery but where clear evidence of fault offset or folded strata is lacking. A fault or fold is mapped as concealed where it can be identified in seismic-reflection data but where no surface deformation is apparent in either multibeam imagery or seismic-reflection data. However, it is important to note that, in areas where multibeam imagery does not exist, a fault mapped as concealed may, in fact, have surface expression that is at a scale undetectable in the seismic-reflection data alone. Therefore, it is possible that the location of a fault or fold mapped as concealed may be just as accurate as that of a fault or fold whose location is mapped with more certainty (that is, with a solid or dashed line).
Magnetic data are particularly useful in guiding structural interpretations where massive Mesozoic bedrock is at or near the seafloor surface because, in these areas, seismic-reflection data often are poor owing to lack of penetration. Such is the case in the nearshore areas from Point Piedras Blancas to Shell Beach, which, with the exception of sediment-covered areas in central Estero Bay, are characterized by bedrock outcrops of predominantly Mesozoic basement rocks that are composed of variably magnetic rock types. Magnetic anomalies represent local spatial variations in the Earth’s magnetic field that indicate the distribution of magnetic minerals—primarily magnetite—in the underlying rocks. In many cases, the volume content of magnetic minerals can be related to rock type, and so it follows that abrupt spatial changes in the amount of magnetic minerals commonly mark lithologic or structural boundaries that would not be detectable in seismic-reflection data alone. For example, the Shoreline Fault is not detectable in seismic-reflection data but, rather, is mapped on the basis of correlation of magnetic-anomaly gradients, as well as on seafloor scarps visible in multibeam imagery.
Reference Cited:
Sliter, R.W., Triezenberg, P.J., Hart, P.E., Watt, J.T., Johnson, S.Y., and Scheirer, D.S., 2009, High resolution seismic-reflection and marine magnetic data along the Hosgri fault zone, central California: U.S. Geological Survey 2009-1100, v. 1.1, <https://pubs.usgs.gov/of/2009/1100/>.
Supplemental_Information:
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
  1. How should this data set be cited?

    Watt, Janet T., 2015, Folds -- Point San Luis map area [sheet 5]:.

    This is part of the following larger work.

    Watt, Janet T., Johnson, Samuel Y., Hartwell, Stephen R., and Roberts, Michelle, 2015, Offshore Geology and Geomorphology from Point Piedras Blancas to Pismo Beach, San Luis Obispo and Santa Barbara Counties, California: Scientific Investigations Map SIM 3327, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -120.998130
    East_Bounding_Coordinate: -120.613617
    North_Bounding_Coordinate: 35.291089
    South_Bounding_Coordinate: 35.072024

  3. What does it look like?

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

    Calendar_Date: 2015
    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):

      • String (58)

    2. What coordinate system is used to represent geographic features?

      The map projection used is WGS 1984 UTM Zone 10N.

      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000100
      Ordinates (y-coordinates) are specified to the nearest 0.000100
      Planar coordinates are specified in Meter

      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    Folds
    lines representing mapped folds (Source: This report)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    FGDCRefNo
    FGDC Digital Cartographic Standard for geologic map symbolization (Source: This report)

    text field containing the reference number for the FGDC Digital Cartographic Standard for geologic map symbolization

    Shape_Length
    Length of feature in internal units. (Source: ESRI)

    Positive real numbers that are automatically generated.


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?

    USGS Pacific Coastal & Marine Science Center
    Attn: Janet Watt
    Geologist
    400 Natural Bridges Drive
    Santa Cruz, CA 95060
    USA

    (831) 460-7565 (voice)
    (831) 427-4748 (FAX)
    jwatt@usgs.gov


Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to aid in assessments and mitigation of geologic hazards in the central California coastal region and to provide sufficient geologic information for land-use and land-management decisions both onshore and offshore.


How was the data set created?

  1. From what previous works were the data drawn?

    CSUMB (2009) (source 1 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_ba2_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 2 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_ba3_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 3 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bb_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 4 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bc_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 5 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bd_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 6 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_be_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 7 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bf_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 8 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bg_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 9 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bh_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 10 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bi_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    CSUMB (2009) (source 11 of 12)
    Seafloor Mapping Lab, California State University Monterey Bay, 20091231, cc_bj_2mbthy.

    Online Links:

    Type_of_Source_Media: digital file of gridded elevation data (ArcInfo GRID)
    Source_Contribution: Digital Elevation Model (2 meter resolution)

    Sliter and others, 2009 (source 12 of 12)
    Sliter, Ray W., Triezenberg, Peter J., Hart, Patrick E., Watt, Janet T., Johnson, Samuel Y., and Scheirer, Daniel S.,, 2009, High-Resolution Seismic-Reflection and Marine Magnetic Data Along the Hosgri Fault Zone, Central California: U.S. Geological Survey Open-File Report 2009-1100, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

    Type_of_Source_Media:
    seismic data files (.sgy files) ASCII lat/long shotpoint files TIFF images of processed seismic lines
    Source_Contribution:
    Digital seismic data used to interpret subsurface geologic structure

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

    Date: 2009 (process 1 of 1)
    Folds were mapped onto shot lines based on the latitude and longitude of seismic picks from Sliter and others (2009). Folds were then adjusted based on folding apparent in the multibeam bathymetry data.

  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?

    Folds were primarily mapped by interpretation of seismic reflection profile data.
    Folds lines were digitized by heads-up screen digitization on to shot point picks from seismic line navigation data - each shot point has an associated lat/long in the survey data. Error is introduced from layback, as well as from interpretation of oblique features, so horizontal accuracy of fault and fold location is estimated to be on the order of 10 to 20 meters.

  3. How accurate are the heights or depths?

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

    Data are complete: no offshore features that could be accurately identified and represented at the compilation scale of 1:24,000 were eliminated or generalized. The smallest area represented is approximately 100 square meters. All geospatial database elements are attributed.

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

    Map elements were visually checked for overshoots, undershoots, duplicate features, polygon closure, and other errors by the lead authors and by the GIS technician(s) who created the digital database. Review drafts of the map were reviewed internally by at least two other geologists for consistency with basic geologic principles and general conformity to USGS mapping standards.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
If physical samples or materials are available, constraints on their on-site access are described in "WR CMG Sample Distribution Policy" at URL: <http://walrus.wr.usgs.gov/infobank/programs/html/main/sample-dist-policy.html>
Use_Constraints:
This information is not intended for navigational purposes.
Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data.
Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.
This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.

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

    U.S. Geological Survey, Coastal and Marine Geology Program
    Attn: Janet Watt
    400 Natural Bridges Drive
    Santa Cruz, CA 95060-5792
    US

    831-460-7565 (voice)
    831-427-4748 (FAX)
    jwatt@usgs.gov

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

  3. What legal disclaimers am I supposed to read?

    This information is not intended for navigational purposes.
    This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
    Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: Jan-2013
Last Reviewed: Jan-2012
Metadata author:
U.S. Geological Survey, Coastal and Marine Geology Program
Attn: Steve Hartwell
400 Natural Bridges Drive
Santa Cruz, CA 95060-5792
US

831-460-7814 (voice)
831-427-4748 (FAX)
shartwell@usgs.gov

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


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