Sand movement along a portion of the northern California coast

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Frequently-anticipated questions:

What does this data set describe?

Title: Sand movement along a portion of the northern California coast
Abstract:
"The long-term beach and offshore sand movement along the portion of the northern California coast between Drakes Bay and the Russian River has been studied. Analysis of hindcast swell data, availability of sand for transport, refraction diagrams and knowledge of stable shapes of sedimentary coastlines suggested that under present conditions little net longshore movement of sand occurs in the area and that the beaches are generally in equilibrium with negligible supply or loss of sand. Surface sediment samples were collected from beaches and offshore zones. Twelve sedimentary petrologic provinces were outlined on the basis of the patterns of heavy mineral distribution. Sands of the provinces nearest the dioritic cliffs of the headlands, Point Reyes, Tomales Point and Bodega Head, have been derived from these cliffs by erosion during the present sedimentation period. The dioritic debris have been supplied from the cliffs at an imperceptibly slow, yet geologically significant, rate. The heavy mineral compositions of the headland are distinctly different from the dioritic sands near the headlands. The mineralogical evidence confirms the results of initial analysis, and shows that negligible quantities of sand move southward around the headlands. In effect the headlands Point Reyes and Bodega Head are barriers to longshore transport. West of Point Reyes Beach the grain size and heavy mineral patterns of distribution indicate that the sands beyond 90 feet are relatively inactive. These sands are probably relic deposits of an ancient period of sand transportation and deposition. The sands of several of the active nearshore provinces apparently were derived and originally made available for coastal transport during ancient sedimentation periods. These active sands now exist in a relatively stable distribution. The dilution rate as a result of present supply is negligible."
Supplemental_Information:
Data digitized for inclusion into usSEABED. (<http://walrus.wr.usgs.gov/usseabed>)
  1. How should this data set be cited?

    Army, U.S., Coastal Engineering Research Center, and Cherry, John, 1965, Sand movement along a portion of the northern California coast: United States Naval Postgraduate School, Monterey, CA.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -121.193
    East_Bounding_Coordinate: -122.78451
    North_Bounding_Coordinate: 38.4634
    South_Bounding_Coordinate: 37.9565

  3. What does it look like?

    CERC_TM14 (.jpg)
    Screen grab of GIS-produced sample distribution, with bathymetry and land for reference.

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

    Calendar_Date: 1963
    Currentness_Reference: Publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Paper

  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):

      • Point (588)

    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 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Decimal degrees.

  7. How does the data set describe geographic features?

    Point
    SDTS point (Source: Source report)

    Sample penetration
    Penetration of sampler (Source: CERC Technical Memo 14)

    Range of values
    Minimum:0.05
    Maximum:0.18
    Units:Meter
    Resolution:0.01

    Q50
    Median diameter of grainsize (Source: CERC Technical Memo 14)

    Range of values
    Minimum:1.49
    Maximum:3.74
    Units:Phi
    Resolution:0.01

    Q10
    Tenth percentile of grainsize distribution (Source: CERC Technical Memo 14)

    Range of values
    Minimum:-0.77
    Maximum:4.32
    Units:Phi
    Resolution:0.01

    Q25
    First quartile of grain size distribution (Source: CERC Technical Memo 14)

    Range of values
    Minimum:-1.14
    Maximum:4.16
    Units:Phi
    Resolution:0.01

    Q75
    Third quartile of grain size distribution (Source: CERC Technical Memo 14)

    Range of values
    Minimum:-2.17
    Maximum:3.25
    Units:Phi
    Resolution:0.01

    Q90
    Ninetieth percentile of grain size distribution (Source: CERC Technical Memo 14)

    Range of values
    Minimum:-1.63
    Maximum:2.83
    Units:Percent
    Resolution:0.0001

    So
    Sorting (Standard deviation of grainsize) (Source: Trask, 1932)

    Range of values
    Minimum:1.04
    Maximum:3.21
    Units:Percent
    Resolution:0.01

    Heavy mineral analysis
    Heavy mineral analysis (Source: CERC Technical Memo 14)

    Percents, in the sand fraction, of apatite, sphene, dark green hornblende, total hornblende, other hornblende, augite, glaucophane, actinolite and tremolite, garnet, hypersthene, ankerite, lawsonite, zircon, epidote, other minerals. Grain counts of biotites and opaques; grain counts of biotite.

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?

    USACE CERC and J. Cherry for collection and analysis of data. usSEABED digitization (data): Jennifer Mendonca (USGS); locations: Nadine Golden (USGS). Formatting corrections: Jane Reid (USGS) and Chris Jenkins (University of Colorado).

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

    U.S. Army Coastal Engineering Research Center
    5201 Little Falls Road NW
    Washington, DC 20016

    Unknown (voice)

Why was the data set created?

"The primary objective of this investigation was to determine the patterns of net or long-term littoral and offshore sand movement along the portion of the northern California coast indicated in Figure 1" (just north of the Russian River to an point between Pt. Reyes and Bolinas Bay)

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: Unknown (process 1 of 1)
    Beach samples collected with a 3-inch diameter steel tube at approximately Bascom's 1951 mid-tide level of reference. The tube was inserted into the sand to a depth of about 7 inches. Two of these samples, about 2 feet apart comprise the total sample for each location. Nearly all the offshore samples were collected by means of 4.5-inch diameter steel tubes, which were dragged 10 to 50 yards. Only the upper one or two inches generally is sampled by this method. In the laboratory the sediment samples were mixed, washed, and subjected to grain size analysis for sieving in the standard manner (Krumbein and Pettijohn, 1938). The heavy minerals from a split of the 53 to 247-micron size fraction were then separated in bromoform (density 2.89) and the strongly magnetic grains removed by a hand magnet. Petrographic counts were done using a line-count method.

    Person who carried out this activity:

    U.S. Army Coastal Engineering Research Center
    5201 Little Falls Road, NW
    Washington, DC 20016

    Unknown (voice)

    Data sources used in this process:
    • Krumbein and Pettijohn, 1938
    • Bascom, 1951

    Data sources produced in this process:

    • CERC_TM14

  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?

    No estimate made for the accuracy of the data in the original report. Data digitized by the USGS and partners were visually compared to the source data, and corrected. Where appropriate, data were tested for completeness using MS Excel. Locations checked using GIS.

  2. How accurate are the geographic locations?

    Navigational technique not noted in report. Digitization report: Data locations determined by georeferencing location figure, using digital coastline in ArcGIS 8.3 (2004) and are given to 0.0001 decimal degrees. Poor reproduction quality of the report did not allow for precise digitization of the locations of samples 1-167; 221a-c; and 394-579; while these samples are included in usSEABED, the locations should be used with caution.

  3. How accurate are the heights or depths?

    No water depths are given in the report.

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

    For inclusion into usSEABED digitized data include Appendix A (Grain size distribution in each of the beach and offshore samples) and Appendix B (Heavy minerals composition of each of the beach and offshore samples).

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

    Data fall within normal ranges for the given parameters.

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:
Cite John Cherry and the U.S. Army Coastal Engineering Research Center as the originators of the data.

  1. Who distributes the data set? (Distributor 1 of 2)

    U.S. Army Coastal Engineering Research Center
    5201 Little Falls Road NW
    Washington, DC 20016

    Need (voice)

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

    CERC Technical Memomorandum 14; P(200) W124tm2 no. 14

  3. What legal disclaimers am I supposed to read?

    Although this dataset has been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data. Users of the data should be aware of limitations of the data due to possible imprecision due to navigational inaccuracies, digitization errors, and limitations of the statistical data.

  4. How can I download or order the data?

  1. Who distributes the data set? (Distributor 2 of 2)

    U.S. Geological Survey
    345 Middlefield Road
    Menlo Park, CA 94025

    650.329.5026 (voice)
    men_lib@usgs.gov

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

    P(200) W124tm2 no. 14

  3. What legal disclaimers am I supposed to read?

    Although this dataset has been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data. Users of the data should be aware of the limitations of the data due to possible imprecision due to navigational inaccuracies, statistical limitations, and digitizing errors.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 2005
Metadata author:
U.S. Geological Survey
c/o Jane A. Reid
Geologist
400 Natural Bridges Drive
Santa Cruz, CA 95060

831-427-4727 (voice)
jareid@usgs.gov

Contact_Instructions: Email preferred
Metadata standard:
CSDGM Version 2 (FGDC-STD-001-1998)

Generated by mp version 2.8.17 on Tue May 16 20:31:18 2006