Radiocarbon measurements from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay

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Frequently anticipated questions:

What does this data set describe?

Title:
Radiocarbon measurements from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay
Abstract:
This data release provides radiocarbon measurements from a core obtained off San Francisquito Creek in South San Francisco Bay.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2002-603-DD Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    McGann, Mary, 20230828, Radiocarbon measurements from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay: data release DOI: 10.5066/P9QQT6KZ, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    McGann, Mary, Starratt, Scott W., Reidy, Liam M., Lorenson, Thomas D., Phillips, R. Lawrence, and Kneeshaw, Tara A., 2023, Radiocarbon measurements, census counts of benthic foraminifera, diatoms, and palynomorphs, and geochemistry from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay: data release DOI:10.5066/P9QQT6KZ, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    Other_Citation_Details:
    Suggested Citation: McGann, M., Starratt, S.W., Reidy, L., Lorenson, T.D., Phillips, R.L., and Kneeshaw, T.A., 2023, Radiocarbon measurements, census counts of benthic foraminifera, diatoms, and palynomorphs, and geochemistry from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay: U.S. Geological Survey data release, https://doi.org/10.5066/P9QQT6KZ.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.0961
    East_Bounding_Coordinate: -122.0961
    North_Bounding_Coordinate: 37.4583
    South_Bounding_Coordinate: 37.4583
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2002
    Ending_Date: 2023
    Currentness_Reference:
    Ground condition at time data were collected.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (3)
    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. The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.978698214.
  7. How does the data set describe geographic features?
    A comma-separated values file with the first line being a header line.
    Results of radiocarbon measurements of fine sediment. (Source: Producer defined.)
    Date_Collected
    Date in year. (Source: Producer defined.)
    Range of values
    Minimum:2002
    Maximum:2002
    Latitude
    Latitude of the site at which the push core was collected. (Source: Producer defined.)
    Range of values
    Minimum:37.4583
    Maximum:37.4583
    Units:decimal degrees
    Resolution:0.0001
    Longitude
    Longitude of the site at which the push core was collected. (Source: Producer defined.)
    Range of values
    Minimum:-122.0961
    Maximum:-122.0961
    Units:decimal degrees
    Resolution:0.0001
    Sample_Upper_Depth_Limit_cm
    The upper depth at which the sediment sample was obtained below the sediment surface in a core. (Source: Producer defined.)
    Range of values
    Minimum:80
    Maximum:170
    Units:centimeters
    Resolution:1
    Sample_Lower_Depth_Limit_cm
    The lower depth at which the sediment sample was obtained below the sediment surface in a core. (Source: Producer defined.)
    Range of values
    Minimum:82
    Maximum:172
    Units:centimeters
    Resolution:1
    Material_Radiocarbon_Dated
    Biological specimen type sent off for radiocarbon measurement. (Source: Producer defined.)
    ValueDefinition
    Presence or absence of biological typeBiological type used for radiocarbon dating
    Radiocarbon_Sample_Weight
    Weight of biological material sent off for radiocarbon measurement. (Source: Producer defined.)
    Range of values
    Minimum:5.07
    Maximum:6.91
    Units:milligrams
    Resolution:0.01
    NOSAMS_Accession_Number
    Lab specific ID from the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility of Woods Hole Oceanographic Institution. (Source: Producer defined) Unique ID given to sample in the NOSAMS lab
    Fraction_Modern
    Fraction modern is a measurement of the deviation of the ratio of delta-Carbon-14 to delta-Carbon-12 of a sample from modern carbon (Stuiver and Polach, 1977). (Source: defined in Stuiver and Polach (1977).)
    Range of values
    Minimum:0.8230
    Maximum:0.9287
    Units:unitless
    Resolution:0.0001
    Fraction_Modern_Error
    Fraction modern error is a measurement of the deviation of the ratio of delta-Carbon-14 to delta-Carbon-12 of a sample from modern carbon (Stuiver and Polach, 1977). (Source: defined in Stuiver and Polach (1977))
    Range of values
    Minimum:0.0016
    Maximum:0.0019
    Units:unitless
    Resolution:0.0001
    Conventional_Radiocarbon_Age_years
    Conventional Radiocarbon Age calculated using the radiocarbon decay equation (Stuiver and Polach, 1977). (Source: defined in Stuiver and Polach (1977).)
    Range of values
    Minimum:595
    Maximum:1560
    Units:years
    Resolution:5
    Conventional_Radiocarbon_Age_Error
    Standard error for Conventional Radiocarbon Age. (Source: defined in Stuiver and Polach (1977).)
    Range of values
    Minimum:15
    Maximum:15
    Units:years
    Resolution:5
    Delta_C13_per_mil
    delta-C-13 is a measure of the ratio of stable isotopes Carbon-13 to Carbon-12, reported in parts per thousand (per mil). (Source: standard reporting value in isotope chemistry)
    Range of values
    Minimum:-3.59
    Maximum:-2.20
    Units:parts per thousand (per mil)
    Resolution:0.01
    Delta_C14_per_mil
    The relative difference between the absolute international standard (base year 1950) and sample activity corrected for age and delta-Carbon-13. (Source: defined in Stuiver and Polach (1977).)
    Range of values
    Minimum:-182.12
    Maximum:-77.16
    Units:parts per thousand (per mil)
    Resolution:0.01
    Delta_R_years
    The relative difference between the regional radiocarbon content of the ocean water and the global ocean waters (known as the regional reservoir-age correction, as defined by Ingram and Southon, 1996) in years. A regional reservoir-age correction of 22 years was used for the benthic foraminifera and molluscan shell fragments (modified from Watt and others 2021). (Source: defined in Ingram and Southon (1996).)
    Range of values
    Minimum:22
    Maximum:22
    Units:parts per thousand (per mil)
    Resolution:1
    Delta_R_error_years
    The error of the relative difference between the regional radiocarbon content of the ocean water and the global ocean waters in years. A regional reservoir-age correction error of plus or minus 1 year was used for the benthic foraminifera and molluscan shell fragments (modified from Watt and others 2021). (Source: Producer defined.)
    Range of values
    Minimum:1
    Maximum:1
    Units:years
    Resolution:1
    Minimum_Calibrated_Age_years_95_percent_conf_level
    The Minimum Calibrated Age in years AD. Reported at the 95 percent confidence level (2-sigma range). Determined using the CALIB 8.2 program (Stuiver and Reimer, 1993) and the Marine20 calibration curve (Heaton and others, 2020). -999 indicates the parameter was not determined. (Source: defined in Heaton and others (2020).)
    Range of values
    Minimum:895
    Maximum:895
    Units:years
    Resolution:1
    Maximum_Calibrated_Age_years_95_percent_conf_level
    The Maximum Calibrated Age in years AD. Reported at the 95 percent confidence level (2-sigma range). Determined using the CALIB 8.2 program (Stuiver and Reimer, 1993) and the Marine20 calibration curve (Heaton and others, 2020). -999 indicates the parameter was not determined. (Source: defined in Heaton and others (2020).)
    Range of values
    Minimum:1164
    Maximum:1164
    Units:years
    Resolution:1
    Median_Calibrated_Age_years_95_percent_conf_level
    The Median Calibrated Age in years AD. Reported at the 95 percent confidence level (2-sigma range). Determined using the CALIB 8.2 program (Stuiver and Reimer, 1993) and the Marine20 calibration curve (Heaton and others, 2020). -999 indicates the parameter was not determined. (Source: defined in Heaton and others (2020).)
    Range of values
    Minimum:1027
    Maximum:1027
    Units:years
    Resolution:1
    Calibrated_Age_Corrected_Error_years
    The error in the Median Calibrated Age in years AD. Reported at the 95 percent confidence level (2-sigma range). Determined using the CALIB 8.2 program (Stuiver and Reimer, 1993) and the Marine20 calibration curve (Heaton and others, 2020). -999 indicates the parameter was not determined. (Source: defined in Heaton and others (2020).)
    Range of values
    Minimum:15
    Maximum:15
    Units:years
    Resolution:1
    Entity_and_Attribute_Overview:
    The first line of the comma-separated values file is a header line.
    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)
    • Mary McGann
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    650-329-4979 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

The urbanized area of downtown Menlo Park is subject to persistent flooding and sediment deposition by San Francisquito Creek in South San Francisco Bay. To mitigate these events, a suite of cores was collected in 2002 at the mouth of the creek to determine sediment depositional rates on the delta. One of those cores was selected for microbiological (pollen, diatoms, and foraminifera) and geochemical analyses to reconstruct a depositional record over the past two millennia. Based on an abrupt change in lithology and faunal assemblages, an instantaneous vertical displacement and deepening of the depositional environment is evident. Coseismic subsidence associated with large fault ruptures may cause these events. An age model based on the first appearances of non-indigenous biota, radiocarbon dates, radiochemistry, and sediment geochemistry suggests the 1868 rupture of the Hayward Fault may have been the cause.

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: 2002 (process 1 of 2)
    A metal core barrel, approximately 9 cm in diameter, was driven into the mudflat slightly northwest of Hooks Point on informally named "Hooks Island" in South San Francisco Bay near Palo Alto, California in 2002 to recover a sediment core. The precise coring location is not available. The core was brought to the the USGS facility in Menlo Park, California and housed in a core refrigerator.
    Date: 2023 (process 2 of 2)
    Samples of benthic foraminifera or molluscan shell fragments for radiocarbon dating were measured by accelerator mass spectrometry (AMS) at the National Ocean Sciences AMS (NOSAMS) Facility of Woods Hole Oceanographic Institution. The radiocarbon ages were obtained by a ratio of 14C to 12C using a 14C half-life of 5568 years (Stuiver and Polach, 1977) and then were converted to calibrated calendar ages (cal years AD) using the CALIB 8.2 program (Stuiver and Reimer, 1993; website accessed in 2022 and 2023) and the Marine20 calibration curve (Heaton and others, 2020). The calibrated ages are reported as the median probability ages at the 95 percent confidence level (2 sigma range). A regional reservoir-age correction (delta R), as defined by Ingram and Southon (1996), of 22 plus or minus 1 years was used for both the benthic foraminiferal and molluscan shell fragment samples based on the delta R used by Watt and others (2022) in nearby San Pablo Bay.
  3. What similar or related data should the user be aware of?
    Stuiver, M., and Polach, H.A., 1977, Discussion: reporting of 14C data.

    Online Links:

    Other_Citation_Details:
    Stuiver, M., and Polach, H.A., 1977, Discussion: Reporting of 14C data: Radiocarbon, v. 19, p. 355-363.
    Stuiver, M., and Reimer, P.J., 1993, Extended 14C Data Base and Revised CALIB 3.0 14C Age Calibration Program.

    Online Links:

    Other_Citation_Details:
    Stuiver, M., and Reimer, P.J., 1993: Radiocarbon, v. 35, p. 215-230.
    Ingram, B.L., and Southon, J.R., 1996, Reservoir ages in eastern Pacific coastal and estuarine waters.

    Online Links:

    Other_Citation_Details:
    Ingram, B.L., and Southon, J.R., 1996, Reservoir ages in eastern Pacific coastal and estuarine water: Radiocarbon, v. 38, p. 573-582.
    Heaton, T.J., Kohler, P., Butzin, M., Bard, E., Reimer, R.W., Austin, W.E.N., Ramsey, C. Bronk, Grootes, P.M., Hughen, K.A., Kromer, B., Reimer, P.J., Adkins, J., Burke, A., Cook, M.S., Olsen, J., and Skinner, L.C., 2020, Marine20-The marine radiocarbon age calibration curve (0-55,000 ca BP).

    Online Links:

    Other_Citation_Details:
    Heaton, T.J., Kohler, P., Butzin, M., Bard, E., Reimer, R.W., Austin, W.E.N., Bronk Ramsey, C., Grootes, P.M., Hughen, K.A., Kromer, B., Reimer, P.J., Adkins, J., Burke, A., Cook, M.S., Olsen J., and Skinner, L.C., 2020, Marine20-The marine radiocarbon age calibration curve (0-55,000 ca BP): Radiocarbon, v. 62, p. 779-820.
    Watt, J.T., McGann, M.L., Takesue, R.K., and Lorenson, T.D., 2022, Marine paleoseismic evidence for seismic and aseismic slip along the Hayward-Rodgers Creek fault system in northern San Pablo Bay.

    Online Links:

    Other_Citation_Details:
    Watt, J.T., McGann, M.L., Takesue, R.K., and Lorenson, T.D., 2022, Marine paleoseismic evidence for seismic and aseismic slip along the Hayward-Rodgers Creek fault system in northern San Pablo Bay. Geochemistry, Geophysics, and Geosystems.: Geochemistry, Geophysics, and Geosystems, Geochemistry, Geophysics, and Geosystems, v. 23, e2021GC010180, 24 p.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The age and associated error of the radiocarbon ages are calculated from the fraction modern and its error and the ages are reported according to conventions that the radiocarbon community has adopted. The Conventional Radiocarbon Age is always reported rounded (the NOSAMS convention is reported at https://www2.whoi.edu/site/nosams/calculations-and-reporting-of-results). The fraction modern values and the ages are listed in this data release, so there can be no misinterpretations of these data. The age for the calibration (not rounded) can be calculated using -8033 multiplied by the log normal of the fraction modern.
  2. How accurate are the geographic locations?
    A formal accuracy assessment of the horizontal positional information in the data set has not been conducted. The horizontal position was estimated based on distances from the modern tidal channel listed on a figure provided to the first author in October 2003. The horizontal accuracy cannot be determined.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the metadata for each part of this data release carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    Data were checked for logical consistency by the NOSAMS staff before release, and by the USGS staff compiling this data release, to confirm that numerical values were not outside a reasonable range for a particular field.

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 USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originators of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in a comma-delimited text file (SFC_radiocarbon_data.csv) which contains results from radiocarbon measurements from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  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 can be viewed with any text editor software.

Who wrote the metadata?

Dates:
Last modified: 28-Aug-2023
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P9QQT6KZ/SFC_radiocarbon_metadata.faq.html>
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