Census counts of diatoms 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:
Census counts of diatoms from core 721-1 obtained in 2002 off San Francisquito Creek in South San Francisco Bay
Abstract:
This data release provides census counts of diatoms in sediments of 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, and Starratt, Scott W., 20230828, Census counts of diatoms 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 (25)
    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 dating, benthic foraminiferal census counts, diatom census counts, palynomorph census counts, and metal content 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:0
    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:0
    Maximum:171
    Units:centimeters
    Resolution:1
    Percent_abundance_diatom_taxa
    Columns 6 to 164 are percent abundances of each diatom taxon in the total diatom assemblage and the sum of these columns is approximately 100 percent. The list of diatom taxa below includes both the abbreviation and the full taxonomic binomial nomenclature and is presented in the same order as the taxa on the data file. (Source: Producer defined)
    ValueDefinition
    List of diatom taxa Achnanthes_brevipes_var._intermedia represents Achnanthes brevipes var. intermedia (Kutzing) Cleve, 1895 Achnanthes_pusilla represents Achnanthes pusilla Grunow in Cleve and Grunow, 1880 Achnanthes_wellsiae represents Achnanthes wellsiae Reimer, 1966 Achnanthes_spp. represents Achnanthes spp. Achnanthidium_groenlandicum represents Achnanthidium groenlandicum Cleve, 1873 Actinocyclus_curvatulus represents Actinocyclus curvatulus (Grunow in A. Schmidt) Cleve, 1901 Actinocyclus_normanii represents Actinocyclus normanii (Gregory) Hustedt, 1957 Actinocyclus_octonarius represents Actinocyclus octonarius Ehrenberg, 1837 Actinoptychus_senarius represents Actinoptychus senarius Ehrenberg, 1843 Amphiprora_complexa represents Amphiprora complexa Gregory, 1857 Amphora_ovalis represents Amphora ovalis (Kutzing) Kutzing, 1844 Amphora_ventricosa represents Amphora ventricosa W. Gregory, 1857 Amphora_spp. represents Amphora spp. Anomoeoneis_sphaerophora_f._costata represents Anomoeoneis sphaerophora f. costata (Kutzing) A.-M. Schmid, 1977 Arachnoidiscus_ehrenbergii represents Arachnoidiscus ehrenbergii J.W. Bailey ex Ehrenberg Aulacoseira_granulata represents Aulacoseira granulata (Ehrenberg) Simonsen, 1979 Aulacoseira_spp. represents Aulacoseira spp. Bacillaria_paxillifer represents Bacillaria paxillifer (O.F. Muller) T. Marsson, 1901 Berkeleya_rutilan represents Berkeleya rutilans (Trentepohl ex Roth) Grunow, 1880 Biremis_circumtexta represents Biremis circumtexta (Meister ex Hustedt) Lange-Bertalot and A. Witkowski, 2000 Caloneis_westii represents Caloneis westii (W. Smith) Hendey, 1964 Campylodiscus_echeneis represents Campylodiscus echeneis Ehrenberg ex Kutzing, 1844 Cavinula_cocconeiformis represents Cavinula cocconeiformis (Gregory ex Greville) D.G. Mann and A.J. Stickle, 1990 Chaetoceros_spore represents Chaetoceros spore Chaetoceros_spp. represents Chaetoceros spp. Cocconeis_decipiens represents Cocconeis decipiens Cleve, 1873 Cocconeis_neodiminuta represents Cocconeis neodiminuta Krammer, 1990 Cocconeis_placentula represents Cocconeis placentula Ehrenberg, 1838 Cocconeis_scutellum represents Cocconeis scutellum Ehrenberg, 1838 Cocconeis_spp. represents Cocconeis spp. Coscinodiscus_marginatus represents Coscinodiscus marginatus Ehrenberg, 1844 Coscinodiscus_obscurus represents Coscinodiscus obscurus A. Schmidt, 1878 Coscinodiscus_radiatus represents Coscinodiscus radiatus Ehrenberg, 1840 Coscinodiscus_spp. represents Coscinodiscus spp. Cosmioneis_pusilla represents Cosmioneis pusilla (W. Smith) D.G. Mann and A.J. Stickle, 1990 Craticula_cuspidata represents Craticula cuspidata (Kutzing) D.G. Mann, 1990 Cyclotella_comta represents Cyclotella comta (Ehrenberg) Kutzing, 1849 Cyclotella_meneghiniana represents Cyclotella meneghiniana Kutzing, 1844 Cyclotella_striata represents Cyclotella striata (Kutzing) Grunow, 1880 Cyclotella_stylorum represents Cyclotella stylorum Brightwell, 1860 Cyclotella_spp. represents Cyclotella spp. Cymatosira_belgica represents Cymatosira belgica Grunow, 1881 Cymatosira_spp. represents Cymatosira spp. Cymbella_pusilla represents Cymbella pusilla Grunow, 1875 Cymbella_ventricosa represents Cymbella ventricosa Kutzing, 1844 Cymbella_spp. represents Cymbella spp. Delphineis_karstenii represents Delphineis karstenii (Boden) G.Fryxell, 1978 Delphineis_minutissima represents Delphineis minutissima (Hustedt) Simonsen, 1987 Denticula_subtilis represents Denticula subtilis Grunow, 1862 Denticula_thermalis represents Denticula thermalis Kutzing, 1844 Diploneis_bombus represents Diploneis bombus (Ehrenberg) Ehrenberg, 1853 Diploneis_diminuta represents Diploneis diminuta (Cleve-Euler) Cleve-Euler, 1953 Diploneis_interrupta represents Diploneis interrupta (Kutzing) Cleve, 1894 Diploneis_oblongella represents Diploneis oblongella (Nageli ex Kutzing) Cleve-Euler, 1922 Diploneis_ovalis represents Diploneis ovalis (Hilse) Cleve, 1891 Diploneis_smithii represents Diploneis smithii (Brebisson) Cleve, 1894 Diploneis_smithii_var._rhombica represents Diploneis smithii var. rhombica Mereschkowsky, 1902 Diploneis_spp. represents Diploneis spp. Encyonopsis_cesatii represents Encyonopsis cesatii (Rabenhorst) Krammer, 1997 Entomoneis_alata represents Entomoneis alata (Ehrenberg) Ehrenberg, 1845 Entomoneis_paludosa represents Entomoneis paludosa (W. Smith) Reimer, 1975 Epithemia_gibberula represents Epithemia gibberula (Ehrenberg) Kutzing 1844 Epithemia_operculata represents Epithemia operculata (C. Agardh) Ruck and Nakov, 2016 Epithemia_sorex represents Epithemia sorex Kutzing, 1844 Epithemia_turgida represents Epithemia turgida (Ehrenberg) Kutzing, 1844 Epithemia_spp. represents Epithemia spp. Eunotia_sp. represents Eunotia sp. Eunotogramma_marinum represents Eunotogramma marinum (W. Smith) H. Peragallo, 1908 Fallacia_pygmaea represents Fallacia pygmaea (Kutzing) A.J. Stickle and D.G. Mann, 1990 Fallacia_sp. represents Fallacia sp. Fragilaria_spp. represents Fragilaria spp. Fragilariopsis_doliolus represents Fragilariopsis doliolus (Wallich) Medlin and P.A. Sims, 1993 Frustulia_interposita represents Frustulia interposita (Lewis) Cleve, 1894 Gomphonema_spp. represents Gomphonema spp. Grammatophora_marina represents Grammatophora marina (Lyngbye) Kutzing, 1844 Gyrosigma_acuminatum represents Gyrosigma acuminatum (Kutzing) Rabenhorst, 1853 Gyrosigma_balticum represents Gyrosigma balticum (Ehrenberg) Rabenhorst, 1853 Gyrosigma_exilis represents Gyrosigma exilis (Grunow) C.W. Reimer, 1966 Gyrosigma_eximium represents Gyrosigma eximium (Thwaites) Boyer, 1927 Gyrosigma_fasciola represents Gyrosigma fasciola (Ehrenberg) J.W. Griffith and Henfrey, 1856 Gyrosigma_spp. represents Gyrosigma spp. Halamphora_granulata represents Halamphora granulata (Gregory) Levkov, 2009 Halamphora_hyalina represents Halamphora hyalina (Kutzing) Rimet and R. Jahn in Rimet and others, 2018 Karayevia_amoena represents Karayevia amoena (Hustedt) Bukhtiyarova, 2006 Lindavia_ocellata represents Lindavia ocellata (Pant.) Nakov, Guillory, M.L. Julius, E.C. Theriot, and A.J. Alverson, 2015 Luticola_cohnii represents Luticola cohnii (Hilse) D.G. Mann, 1990 Luticola_mutica represents Luticola mutica (Kutzing) D.G. Mann, 1990 Mastogloia_elliptica represents Mastogloia elliptica (C. Agardh) Cleve, 1893 Melosira_moniliformis represents Melosira moniliformis (O.F. Muller) C. Agardh, 1824 Melosira_nummuloides represents Melosira nummuloides C. Agardh, 1824 Melosira_sp. represents Melosira sp. Navicula_abunda represents Navicula abunda Hustedt, 1955 Navicula_cincta represents Navicula cincta (Ehrenberg) Ralfs, 1861 Navicula_cryptocephala represents Navicula cryptocephala Kutzing, 1844 Navicula_digitoradiata represents Navicula digitoradiata (Gregory) Ralfs, 1861 Navicula_gregaria represents Navicula gregaria Donkin, 1861 Navicula_peregrina represents Navicula peregrina (Ehrenberg) Kutzing, 1844 Navicula_perminuta represents Navicula perminuta Grunow, 1880 Navicula_salinarum represents Navicula salinarum Grunow, 1880 Navicula_scopulorum represents Navicula scopulorum de Brebisson ex Kutzing, 1849 Navicula_spicula represents Navicula spicula (Hickie) Cleve, 1894 Navicula_tripunctata represents Navicula tripunctata (O.F. Muller) Bory de Saint-Vincent, 1822 Navicula_spp. represents Navicula spp. Neodenticula_seminae represents Neodenticula seminae (R. Simonsen and T. Kanaya) F. Akiba and Y. Yanagisawa, 1986 Nitzschia_fasciculata represents Nitzschia fasciculata (Grunow) Grunow, 1881 Nitzschia_frustulum represents Nitzschia frustulum (Kutzing) Grunow, 1880 Nitzschia_gandersheimiensis represents Nitzschia gandersheimiensis Krasske, 1927 Nitzschia_hummii represents Nitzschia hummii Hustedt, 1955 Nitzschia_longa_var._longa represents Nitzschia longa var. longa Grunow in Cleve and Grunow, 1880 Nitzschia_navicularis represents Nitzschia navicularis (Brebisson) Grunow, 1880 Nitzschia_palea represents Nitzschia palea (Kutzing) W. Smith, 1856 Nitzschia_paleacea represents Nitzschia paleacea Grunow in Van Heurck, 1881 Nitzschia_pusilla represents Nitzschia pusilla Grunow, 1862 Nitzschia_recta represents Nitzschia recta Hantzsch ex Rabenhorst, 1862 Nitzschia_scalpelliformis represents Nitzschia scalpelliformis Grunow, 1880 Nitzschia_sigma represents Nitzschia sigma (Kutzing) W. Smith, 1853 Nitzschia_sigmaformis_var._sigmaformis represents Nitzschia sigmaformis var. sigmaformis Hustedt, 1955 Nitzschia_vitrea represents Nitzschia vitrea G. Norman, 1861 Nitzschia_spp. represents Nitzschia spp. Odontella_aurita represents Odontella aurita (Lyngbye) C. Agardh, 1832 Opephora_schwartzii represents Opephora schwartzii (Grunow) Petit ex Pelletan, 1889 Paralia_sulcata_(small_<20_microns) represents Paralia sulcata (Ehrenberg) Cleve, 1873 (large > 20 microns) Paralia_sulcata_(small_<20_microns) represents Paralia sulcata (Ehrenberg) Cleve, 1873 (small < 20 microns) Petrodictyon_gemma represents Petrodictyon gemma (Ehrenberg) D.G. Mann, 1990 Pinnularia_elegans represents Pinnularia elegans (W. Smith) K. Krammer, 1992 Pinnularia_spp. represents Pinnularia spp. Plagiogramma_minus represents Plagiogramma minus (W. Gregory) Chunlian Li, Ashworth and Witkowski in Li and others, 2020 Plagiotropis_vitrea represents Plagiotropis vitrea (W. Smith) Grunow, 1880 Planothidium_lanceolatum represents Planothidium lanceolatum (Brebisson ex Kutzing) Bukhtiyarova, 1999 Planothidium_rostratoholarcticum represents Planothidium rostratoholarcticum Lange-Bertalot and Bak in Bak and Lange-Bertalot, 2014 Pleurosigma_normanii represents Pleurosigma normanii Ralfs, 1861 Pleurosigma_strigosum represents Pleurosigma strigosum W. Smith, 1852 Pleurosigma_spp. represents Pleurosigma spp. Pseudostaurosira_brevistriata represents Pseudostaurosira brevistriata (Grunow) D.M. Williams and Round, 1987 Rhaphoneis_amphiceros represents Rhaphoneis amphiceros (Ehrenberg) Ehrenberg, 1844 Rhaphoneis_margaritalimbata represents Rhaphoneis margaritalimbata Mertz, 1966 Rhaphoneis_surirella represents Rhaphoneis surirella (Ehrenberg) Grunow, 1881 Rhaphoneis_surirelloides represents Rhaphoneis surirelloides Simonsen, 1974 Rhaphoneis_spp. represents Rhaphoneis spp. Rhizosolenia_hebetata represents Rhizosolenia hebetata Bailey, 1856 Rhizosolenia_spp. represents Rhizosolenia spp. Rhoicosphenia_abbreviata represents Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot, 1980 Scolioneis_tumida represents Scolioneis tumida (Brebisson ex Kutzing) D.G. Mann, 1990 Stauroneis_anceps represents Stauroneis anceps var. obtusa Grunow in Cleve, 1894 Stauroneis_simulans represents Stauroneis simulans (Donkin) R.R. Ross, 1986 Staurophora_amphioxys represents Staurophora amphioxys (Gregory) D.G. Mann, 1990 Staurosira_construens_var._venter represents Staurosira construens var. venter (Ehrenberg) P.B. Hamilton, 1992 Staurosirella_lapponica represents Staurosirella lapponica (Grunow) D.M. Williams and Round, 1987 Staurosirella_leptostauron represents Staurosirella leptostauron (Ehrenberg) D.M. Williams and Round, 1987 Staurosirella_martyi represents Staurosirella martyi (Heribaud) E. Morales and Manoylov, 2006 Staurosirella_pinnata represents Staurosirella pinnata (Ehrenberg) D.M. Williams and Round, 1987 Stenopterobia_curvula represents Stenopterobia curvula (W. Smith) Krammer, 1987 Stephanodiscus_astraea represents Stephanodiscus astraea (Ehrenberg) Grunow, 1880 Stephanodiscus_spp. represents Stephanodiscus spp. Surirella_fastuosa represents Surirella fastuosa (Ehrenberg) Ehrenberg, 1843 Surirella_ovata represents Surirella ovata Kutzing, 1844 Surirella_sp. represents Surirella sp. Ulnaria_ulna represents Ulnaria ulna (Nitzsch) Compere, 2001 Ulnaria_sp. represents Ulnaria sp. Tabularia_tabulata represents Tabularia tabulata (C. Agardh) Snoeijs, 1992 Thalassionema_bacillaris represents Thalassionema bacillaris (Heiden and Kolbe) Kolbe, 1955 Thalassionema_nitzschioides represents Thalassionema nitzschioides (Grunow) Mereschkowsky, 1902 Thalassiosira_decipien represents Thalassiosira decipiens (Grunow) E.G. Jorgensen, 1905 Thalassiosira_eccentrica represents Thalassiosira eccentrica (Ehrenberg) Cleve, 1904 Thalassiosira_hendeyi represents Thalassiosira hendeyi Hasle and G.Fryxell, 1977 Thalassiosira_nodulolineata represents Thalassiosira nodulolineata (Hendey) Hasle and Fryxell, 1977 Thalassiosira_nordenskioeldii represents Thalassiosira nordenskioeldii Cleve, 1873 Thalassiosira_oestrupii represents Thalassiosira oestrupii (Ostenfeld) Hasle, 1972 Thalassiosira_pacifica represents Thalassiosira pacifica Gran and Angst, 1931 Thalassiosira_proschkinae represents Thalassiosira proschkinae Makarova, 1979 Thalassiosira_punctigera represents Thalassiosira punctigera (Castracane) Hasle, 1983 Thalassiosira_wongii represents Thalassiosira wongii Mahood in Mahood, Fryxell and McMillan, 1986 Thalassiosira_spp. represents Thalassiosira spp. Trachyneis_aspera represents Trachyneis aspera (Ehrenberg) Cleve, 1894 Trachysphenia_acuminata represents Trachysphenia acuminata M. Peragallo in Tempere and Peragallo, 1910 Triceratium_dubium represents Triceratium dubium Brightwell, 1859 Tryblionella_acuminata represents Tryblionella acuminata W. Smith, 1853 Tryblionella_gracilis represents Tryblionella gracilis W. Smith, 1853 Tryblionella_granulata represents Tryblionella granulata (Grunow) D.G. Mann, 1990 Tryblionella_granulata_var._1 represents Tryblionella granulata var. 1 Laws (1988) Tryblionella_levidensis represents Tryblionella levidensis W. Smith, 1856 Tryblionella_punctata represents Tryblionella punctata W. Smith, 1853 Tryblionella_punctata_var._coarctata represents Tryblionella punctata var. coarctata (Grunow in Cleve and Muller) Pelletan, 1889 Tryblionella_scalaris represents Tryblionella scalaris (Ehrenberg) P. Siver and P.B. Hamilton, 2005 Unknown_Laws_(1988)_pl._12_fig._12 represents Unknown, Laws (1988), pl. 12, fig. 12percent abundance ranging from 0-100
    Total_Diatoms_Counted
    Total number of diatoms recovered in each sample. (Source: Producer defined)
    Range of values
    Minimum:198
    Maximum:203
    Units:each
    Resolution:1
    Chrysophyte_stomatocysts
    Total number of Chrysophyte stomatocysts recovered in each sample. (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:4
    Units:each
    Resolution:1
    Phytoliths
    Total number of phytoliths recovered in each sample. (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:1
    Units:each
    Resolution:1
    Silicoflagellates
    Total number of silicoflagellates recovered in each sample. (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:1
    Units:each
    Resolution:1
    Sponge_spicules
    Total number of sponge spicules recovered in each sample. (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:7
    Units:each
    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
    • Scott W. Starratt
  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: 2003 (process 2 of 2)
    Twenty-five samples of approximately 1 cubic cm were obtained from core 721-1 for diatom analysis every 10 cm downcore and every 5 cm from 150-80 cm. Samples were processed using 30 percent hydrogen peroxide, 37 percent hydrochloric acid, and 70 percent nitric acid solutions to remove carbonate and organic matter and a 5 percent sodium pyrophosphate solution to deflocculate the remaining clay. The samples were then washed repeatedly with di-ionized water until neutralized. Approximately 50 microliters of the resulting suspension were dried on a 22 X 30 mm coverslip and permanently mounted using Naphrax. Two hundred frustules per sample were enumerated, using a Leica DM LB2 microscope with Nomarski differential interference contrast optics at magnifications of 630X and 1,000X. Data for some taxa were combined because similar or gradational morphological characteristics prevented species differentiation in some samples. The diatom slides and residues of this study are on file at the U.S. Geological Survey, Menlo Park, California.
  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?
    Microscopes are operationally checked every year to assure optics are aligned and visual acuity can be maximized during sorting and identifications. Specimen identifications were compared to reference material (actual specimens and published monographs) to ensure idenfications were accurate. Specimen enumeration (counts) were checked with original laboratory bench sorting sheets to assure numbers were correct, and the sorting and data entry into spreadsheets was rechecked at least once.
  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 laboratory staff before release to confirm that numerical values were not outside a reasonable range for a particular field. Cumulative counts of percentage data for the total diatom assemblage had to equal approximately 100% to ensure numbers were reported correctly.

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_diatoms_data.csv) which contains census counts of diatoms 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_diatoms_metadata.faq.html>
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