Sediment grain-size distributions from sediment cores collected offshore Cascadia, during field activities 2020-633-FA and 2021-636-FA

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What does this data set describe?

1. How might this data set be cited?
   Hill, Jenna C., SeanPaul M. La Selle, Paull, Charles K., Gwiazda, Roberto, Lundsten, Eve M., Nieminski, Nora M., McGann, Mary L., Lorenson, Thomas D., Watt, Janet T., Caissie, Beth, and Starratt, Scott W., 20260108, Sediment grain-size distributions from sediment cores collected offshore Cascadia, during field activities 2020-633-FA and 2021-636-FA: data release DOI:10.5066/P1JUTTAN, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P1JUTTAN

   This is part of the following larger work.
   Hill, Jenna C., SeanPaul M. La Selle, Paull, Charles K., Gwiazda, Roberto, Lundsten, Eve M., Nieminski, Nora M., McGann, Mary L., Lorenson, Thomas D., Watt, Janet T., Caissie, Beth, and Starratt, Scott W., 2026, Sediment core data from offshore Cascadia - USGS field activities 2020-633-FA and 2021-636-FA: data release DOI:10.5066/P1JUTTAN, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

   Online Links:

   • https://doi.org/10.5066/P1JUTTAN

   Other_Citation_Details:

   Suggested Citation: Hill, J.C, La Selle, S.M., Paull, C.K., Gwiazda, R., Lundsten, E.M., Nieminski, N.M., McGann, M.L., Lorenson, T., Watt, J.T., Caissie, B., and Starratt, S., 2026, Sediment core data from offshore Cascadia during field activities 2020-633-FA and 2021-636-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P1JUTTAN.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -125.33482
   East_Bounding_Coordinate: -125.21519
   North_Bounding_Coordinate: 44.32656
   South_Bounding_Coordinate: 41.71177
   

3. What does it look like?
4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 09-Sep-2020

   Ending_Date: 31-Aug-2021

   Currentness_Reference:

   ground condition

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

   Geospatial_Data_Presentation_Form: Comma Separated Value (CSV) tabular data
   

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 (316)
   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 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in Decimal Degrees. The horizontal datum used is 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 1/298.257223563.
      
7. How does the data set describe geographic features?

   2020-633-FA_2021-636-FA_cores_grainsize.csv

   Comma Separated Value (.csv) file containing grainsize data. (Source: producer defined)

   field_activity_number

   Field Activity Number (Source: producer defined) Unique identifier for the U.S. Geological Survey field activity

   sample_id

   Name of sample in FieldActivity-CoreID-Depth format, where FieldActivity is the year and activity number (for example 2021-636 for 2021-636-FA), CoreID is the unique name given to a core (for example VC1024 is vibracore 1024), and Depth is the depth interval in centimeters in the core from which the sample was collected. Samples that were split and analyzed twice are identified by the "duplicate" appended to the Sample I.D. (Source: producer defined) Unique identifier for the sample determined while subsampling in the laboratory.

   lab_id

   Name of sample in FieldActivity_CoreID_Depth format, where FieldActivity is the year and activity number (for example 21-636FA for 2021-636-FA), CoreID is the unique name given to a core (for example VC1024 is vibracore 1024), and Depth is the depth interval in centimeters in the core from which the sample was collected. Samples that were split and analyzed twice are identified by the "dup" (for "duplicate") appended to the Lab I.D. (Source: producer defined) Unique identifier for the sample given during analysis in the lab

   date_collected

   Date of grainsize subsample collection in the lab in mm-dd-yyyy format. Not to be confused with the date the grain size analyses were performed. (Source: producer defined)

   Range of values
   Minimum:	9/16/2020
   Maximum:	8/25/2021
   Units:	Dates in mm-dd-yyyy format

   latitude

   Latitude of site where sample was collected, in decimal degrees. (Source: producer defined)

   Range of values
   Minimum:	41.711768
   Maximum:	44.32656
   Units:	decimal degrees

   longitude

   Longitude of site where sample was collected, in decimal degrees. (Source: producer defined)

   Range of values
   Minimum:	-125.334818
   Maximum:	-125.215187
   Units:	decimal degrees

   sample_type

   Type of sample collected, subsampled from a core (Vibracore subsample). (Source: producer defined)

   Value	Definition
   Vibracore subsample	The associated sample was subsampled from a split vibracore in the laboratory and placed in a plastic sample bag.

   wt_percent_in_-4.00phi_or_16mm_bin

   Weight percent of sample with grain diameter greater than -4.00 phi, or 16 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-3.75phi_or_13.5mm_bin

   Weight percent of sample with grain diameter between -4.00 and -3.75 phi, or 13.5 and 16 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-3.50phi_or_11.2mm_bin

   Weight percent of sample with grain diameter between -3.75 and -3.50 phi, or 11.2 and 13.5 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-3.25phi_or_9.51mm_bin

   Weight percent of sample with grain diameter between -3.50 and -3.25 phi, or 9.51 and 11.2 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-3.00phi_or_8mm_bin

   Weight percent of sample with grain diameter between -3.25 and -3.00 phi, or 8 and 9.51 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-2.75phi_or_6.73mm_bin

   Weight percent of sample with grain diameter between -3.00 and -2.75 phi, or 6.73 and 8 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-2.50phi_or_5.66mm_bin

   Weight percent of sample with grain diameter between -2.75 and -2.50 phi, or 5.66 and 6.73 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-2.25phi_or_4.76mm_bin

   Weight percent of sample with grain diameter between -2.50 and -2.25 phi, or 4.76 and 5.66 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-2.00phi_or_4mm_bin

   Weight percent of sample with grain diameter between -2.25 and -2.00 phi, or 4 and 4.76 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-1.75phi_or_3.36mm_bin

   Weight percent of sample with grain diameter between -2.00 and -1.75 phi, or 3.36 and 4 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_-1.50phi_or_2.83mm_bin

   Weight percent of sample with grain diameter between -1.75 and -1.50 phi, or 2.83 and 3.36 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.0
   Units:	percentage

   wt_percent_in_-1.25phi_or_2.38mm_bin

   Weight percent of sample with grain diameter between -1.50 and -1.25 phi, or 2.38 and 2.83 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.0
   Units:	percentage

   wt_percent_in_-1.00phi_or_2mm_bin

   Weight percent of sample with grain diameter between -1.25 and -1.00 phi, or 2 and 2.38 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.0
   Units:	percentage

   wt_percent_in_-0.75phi_or_1.68mm_bin

   Weight percent of sample with grain diameter between -1.00 and -0.75 phi, or 1.68 and 2 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.0
   Units:	percentage

   wt_percent_in_-0.50phi_or_1.41mm_bin

   Weight percent of sample with grain diameter between -0.75 and -0.50 phi, or 1.41 and 1.68 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.0
   Units:	percentage

   wt_percent_in_-0.25phi_or_1.19mm_bin

   Weight percent of sample with grain diameter between -0.50 and -0.25 phi, or 1.19 and 1.41 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.0
   Units:	percentage

   wt_percent_in_0.00phi_or_1mm_bin

   Weight percent of sample with grain diameter between -0.25 and 0.00 phi, or 1 and 1.19 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.01
   Units:	percentage

   wt_percent_in_0.25phi_or_0.8409mm_bin

   Weight percent of sample with grain diameter between 0.00 and 0.25 phi, or 0.8409 and 1 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.14
   Units:	percentage

   wt_percent_in_0.50phi_or_0.7071mm_bin

   Weight percent of sample with grain diameter between 0.25 and 0.50 phi, or 0.7071 and 0.8409 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.58
   Units:	percentage

   wt_percent_in_0.75phi_or_0.5946mm_bin

   Weight percent of sample with grain diameter between 0.50 and 0.75 phi, or 0.5946 and 0.7071 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	1.06
   Units:	percentage

   wt_percent_in_1.00phi_or_0.5mm_bin

   Weight percent of sample with grain diameter between 0.75 and 1.00 phi, or 0.5 and 0.5946 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	1.4
   Units:	percentage

   wt_percent_in_1.25phi_or_0.4204mm_bin

   Weight percent of sample with grain diameter between 1.00 and 1.25 phi, or 0.4204 and 0.5 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	1.5
   Units:	percentage

   wt_percent_in_1.50phi_or_0.3536mm_bin

   Weight percent of sample with grain diameter between 1.25 and 1.50 phi, or 0.3536 and 0.4204 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	1.34
   Units:	percentage

   wt_percent_in_1.75phi_or_0.2973mm_bin

   Weight percent of sample with grain diameter between 1.50 and 1.75 phi, or 0.2973 and 0.3536 mm. (Source: producer defined)

   Range of values
   Minimum:	0.0
   Maximum:	1.11
   Units:	percentage

   wt_percent_in_2.00phi_or_0.25mm_bin

   Weight percent of sample with grain diameter between 1.75 and 2.00 phi, or 0.25 and 0.2973 mm. (Source: producer defined)

   Range of values
   Minimum:	0.0
   Maximum:	1.51
   Units:	percentage

   wt_percent_in_2.25phi_or_0.2102mm_bin

   Weight percent of sample with grain diameter between 2.00 and 2.25 phi, or 0.2102 and 0.25 mm. (Source: producer defined)

   Range of values
   Minimum:	0.0
   Maximum:	1.47
   Units:	percentage

   wt_percent_in_2.50phi_or_0.1768mm_bin

   Weight percent of sample with grain diameter between 2.25 and 2.50 phi, or 0.1768 and 0.2102 mm. (Source: producer defined)

   Range of values
   Minimum:	0.00078
   Maximum:	1.08
   Units:	percentage

   wt_percent_in_2.75phi_or_0.1487mm_bin

   Weight percent of sample with grain diameter between 2.50 and 2.75 phi, or 0.1487 and 0.1768 mm. (Source: producer defined)

   Range of values
   Minimum:	0.043993
   Maximum:	1.11
   Units:	percentage

   wt_percent_in_3.00phi_or_0.125mm_bin

   Weight percent of sample with grain diameter between 2.75 and 3.00 phi, or 0.125 and 0.1487 mm. (Source: producer defined)

   Range of values
   Minimum:	0.15
   Maximum:	1.19
   Units:	percentage

   wt_percent_in_3.25phi_or_0.1051mm_bin

   Weight percent of sample with grain diameter between 3.00 and 3.25 phi, or 0.1051 and 0.125 mm. (Source: producer defined)

   Range of values
   Minimum:	0.14
   Maximum:	1.24
   Units:	percentage

   wt_percent_in_3.50phi_or_0.08839mm_bin

   Weight percent of sample with grain diameter between 3.25 and 3.50 phi, or 0.08839 and 0.1051 mm. (Source: producer defined)

   Range of values
   Minimum:	0.23
   Maximum:	1.34
   Units:	percentage

   wt_percent_in_3.75phi_or_0.07433mm_bin

   Weight percent of sample with grain diameter between 3.50 and 3.75 phi, or 0.07433 and 0.08839 mm. (Source: producer defined)

   Range of values
   Minimum:	0.410042
   Maximum:	1.53
   Units:	percentage

   wt_percent_in_4.00phi_or_0.0625mm_bin

   Weight percent of sample with grain diameter between 3.75 and 4.00 phi, or 0.0625 and 0.07433 mm. (Source: producer defined)

   Range of values
   Minimum:	0.590061
   Maximum:	2.380273
   Units:	percentage

   wt_percent_in_4.25phi_or_0.052556mm_bin

   Weight percent of sample with grain diameter between 4.00 and 4.25 phi, or 0.052556 and 0.0625 mm. (Source: producer defined)

   Range of values
   Minimum:	0.79996
   Maximum:	3.560409
   Units:	percentage

   wt_percent_in_4.50phi_or_0.044194mm_bin

   Weight percent of sample with grain diameter between 4.25 and 4.50 phi, or 0.044194 and 0.052556 mm. (Source: producer defined)

   Range of values
   Minimum:	1.23
   Maximum:	4.740544
   Units:	percentage

   wt_percent_in_4.75phi_or_0.037163mm_bin

   Weight percent of sample with grain diameter between 4.50 and 4.75 phi, or 0.037163 and 0.044194 mm. (Source: producer defined)

   Range of values
   Minimum:	1.87
   Maximum:	5.540636
   Units:	percentage

   wt_percent_in_5.00phi_or_0.03125mm_bin

   Weight percent of sample with grain diameter between 4.75 and 5.00 phi, or 0.03125 and 0.037163 mm. (Source: producer defined)

   Range of values
   Minimum:	2.45
   Maximum:	5.780663
   Units:	percentage

   wt_percent_in_5.25phi_or_0.02628mm_bin

   Weight percent of sample with grain diameter between 5.00 and 5.25 phi, or 0.02628 and 0.03125 mm. (Source: producer defined)

   Range of values
   Minimum:	2.75
   Maximum:	5.869728
   Units:	percentage

   wt_percent_in_5.50phi_or_0.0221mm_bin

   Weight percent of sample with grain diameter between 5.25 and 5.50 phi, or 0.0221 and 0.02628 mm. (Source: producer defined)

   Range of values
   Minimum:	2.83
   Maximum:	5.739734
   Units:	percentage

   wt_percent_in_5.75phi_or_0.01858mm_bin

   Weight percent of sample with grain diameter between 5.50 and 5.75 phi, or 0.01858 and 0.0221 mm. (Source: producer defined)

   Range of values
   Minimum:	3.05
   Maximum:	5.529744
   Units:	percentage

   wt_percent_in_6.00phi_or_0.01563mm_bin

   Weight percent of sample with grain diameter between 5.75 and 6.00 phi, or 0.01563 and 0.01858 mm. (Source: producer defined)

   Range of values
   Minimum:	3.55
   Maximum:	5.729031
   Units:	percentage

   wt_percent_in_6.25phi_or_0.01314mm_bin

   Weight percent of sample with grain diameter between 6.00 and 6.25 phi, or 0.01314 and 0.01563 mm. (Source: producer defined)

   Range of values
   Minimum:	4.28
   Maximum:	5.98
   Units:	percentage

   wt_percent_in_6.50phi_or_0.01105mm_bin

   Weight percent of sample with grain diameter between 6.25 and 6.50 phi, or 0.01105 and 0.01314 mm. (Source: producer defined)

   Range of values
   Minimum:	4.330497
   Maximum:	6.050121
   Units:	percentage

   wt_percent_in_6.75phi_or_0.00929mm_bin

   Weight percent of sample with grain diameter between 6.50 and 6.75 phi, or 0.00929 and 0.01105 mm. (Source: producer defined)

   Range of values
   Minimum:	4.230486
   Maximum:	6.341786
   Units:	percentage

   wt_percent_in_7.00phi_or_0.00781mm_bin

   Weight percent of sample with grain diameter between 6.75 and 7.00 phi, or 0.00781 and 0.00929 mm. (Source: producer defined)

   Range of values
   Minimum:	4.080468
   Maximum:	6.3918
   Units:	percentage

   wt_percent_in_7.25phi_or_0.00657mm_bin

   Weight percent of sample with grain diameter between 7.00 and 7.25 phi, or 0.00657 and 0.00781 mm. (Source: producer defined)

   Range of values
   Minimum:	3.900448
   Maximum:	6.241304
   Units:	percentage

   wt_percent_in_7.50phi_or_0.00552mm_bin

   Weight percent of sample with grain diameter between 7.25 and 7.50 phi, or 0.00552 and 0.00657 mm. (Source: producer defined)

   Range of values
   Minimum:	3.730428
   Maximum:	6.011256
   Units:	percentage

   wt_percent_in_7.75phi_or_0.00465mm_bin

   Weight percent of sample with grain diameter between 7.50 and 7.75 phi, or 0.00465 and 0.00552 mm. (Source: producer defined)

   Range of values
   Minimum:	3.450396
   Maximum:	5.521154
   Units:	percentage

   wt_percent_in_8.00phi_or_0.00391mm_bin

   Weight percent of sample with grain diameter between 7.75 and 8.00 phi, or 0.00391 and 0.00465 mm. (Source: producer defined)

   Range of values
   Minimum:	3.250373
   Maximum:	5.15825
   Units:	percentage

   wt_percent_in_8.25phi_or_0.00329mm_bin

   Weight percent of sample with grain diameter between 8.00 and 8.25 phi, or 0.00329 and 0.00391 mm. (Source: producer defined)

   Range of values
   Minimum:	3.030348
   Maximum:	4.737993
   Units:	percentage

   wt_percent_in_8.50phi_or_0.00276mm_bin

   Weight percent of sample with grain diameter between 8.25 and 8.50 phi, or 0.00276 and 0.00329 mm. (Source: producer defined)

   Range of values
   Minimum:	2.730313
   Maximum:	4.188226
   Units:	percentage

   wt_percent_in_8.75phi_or_0.00232mm_bin

   Weight percent of sample with grain diameter between 8.50 and 8.75 phi, or 0.00232 and 0.00276 mm. (Source: producer defined)

   Range of values
   Minimum:	2.46
   Maximum:	3.768404
   Units:	percentage

   wt_percent_in_9.00phi_or_0.00195mm_bin

   Weight percent of sample with grain diameter between 8.75 and 9.00 phi, or 0.00195 and 0.00232 mm. (Source: producer defined)

   Range of values
   Minimum:	2.18
   Maximum:	3.42
   Units:	percentage

   wt_percent_in_9.25phi_or_0.00164mm_bin

   Weight percent of sample with grain diameter between 9.00 and 9.25 phi, or 0.00164 and 0.00195 mm. (Source: producer defined)

   Range of values
   Minimum:	1.96
   Maximum:	3.16
   Units:	percentage

   wt_percent_in_9.50phi_or_0.00138mm_bin

   Weight percent of sample with grain diameter between 9.25 and 9.50 phi, or 0.00138 and 0.00164 mm. (Source: producer defined)

   Range of values
   Minimum:	1.79
   Maximum:	2.95
   Units:	percentage

   wt_percent_in_9.75phi_or_0.00116mm_bin

   Weight percent of sample with grain diameter between 9.50 and 9.75 phi, or 0.00116 and 0.00138 mm. (Source: producer defined)

   Range of values
   Minimum:	1.67
   Maximum:	2.8
   Units:	percentage

   wt_percent_in_9.99phi_or_0.00098mm_bin

   Weight percent of sample with grain diameter between 9.75 and 9.99 phi, or 0.00098 and 0.00116 mm. (Source: producer defined)

   Range of values
   Minimum:	1.5
   Maximum:	2.52
   Units:	percentage

   wt_percent_in_10.25phi_or_0.00082mm_bin

   Weight percent of sample with grain diameter between 9.99 and 10.25 phi, or 0.00082 and 0.00098 mm. (Source: producer defined)

   Range of values
   Minimum:	1.43
   Maximum:	2.41
   Units:	percentage

   wt_percent_in_10.50phi_or_0.00069mm_bin

   Weight percent of sample with grain diameter between 10.25 and 10.50 phi, or 0.00069 and 0.00082 mm. (Source: producer defined)

   Range of values
   Minimum:	1.19
   Maximum:	2.01
   Units:	percentage

   wt_percent_in_10.75phi_or_0.00058mm_bin

   Weight percent of sample with grain diameter between 10.50 and 10.75 phi, or 0.00058 and 0.00069 mm. (Source: producer defined)

   Range of values
   Minimum:	0.96
   Maximum:	1.62
   Units:	percentage

   wt_percent_in_10.99phi_or_0.00049mm_bin

   Weight percent of sample with grain diameter between 10.75 and 10.99 phi, or 0.00049 and 0.00058 mm. (Source: producer defined)

   Range of values
   Minimum:	0.67
   Maximum:	1.12
   Units:	percentage

   wt_percent_in_11.25phi_or_0.0004mm_bin

   Weight percent of sample with grain diameter between 10.99 and 11.25 phi, or 0.0004 and 0.00049 mm. (Source: producer defined)

   Range of values
   Minimum:	0.38
   Maximum:	0.64
   Units:	percentage

   wt_percent_in_11.48phi_or_0.00035mm_bin

   Weight percent of sample with grain diameter between 11.25 and 11.48 phi, or 0.00035 and 0.0004 mm. (Source: producer defined)

   Range of values
   Minimum:	0.09
   Maximum:	0.15
   Units:	percentage

   wt_percent_in_12.02phi_or_0.000241mm_bin

   Weight percent of sample with grain diameter between 11.48 and 12.02 phi, or 0.000241 and 0.00035 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   wt_percent_in_13.02phi_or_0.00012mm_bin

   Weight percent of sample with grain diameter between 12.02 and 13.02 phi, or 0.00012 and 0.000241 mm. (Source: producer defined)

   Range of values
   Minimum:	0.000000
   Maximum:	0.000000
   Units:	percentage

   Entity_and_Attribute_Overview: The first line of the csv 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)
   • Jenna C. Hill
   • SeanPaul M. La Selle
   • Charles K. Paull
   • Roberto Gwiazda
   • Eve M. Lundsten
   • Nora M. Nieminski
   • Mary L. McGann
   • Thomas D. Lorenson
   • Janet T. Watt
   • Beth Caissie
   • Scott W. Starratt
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   PCMSC Science Data Coordinator

   U.S. Geological Survey, Pacific Coastal and Marine Science Center

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov

Why was the data set created?

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: 25-Aug-2021 (process 1 of 2)

   Subsurface sediments were subsampled from vibracores VC874 and VC1024 by hand in the USGS Pacific Coastal and Marine Science Center (PCMSC) sediment lab.

   Date: 29-Jun-2023 (process 2 of 2)

   Grain-size analysis was conducted by the PCMSC sediment lab using a Beckman Coulter LS 13 320 particle size analyzer with an aqueous liquid module attachment. PCMSC procedures are modified from those described in Carver (1971) and Folk (1974, 1980). 5-50 grams of sediment was sub-sampled and at least 10 milliliters of 30 percent hydrogen peroxide were added to oxidize for at least 12 hours to remove organics. The samples were then heated to 250 degrees Celsius to drive off excess hydrogen peroxide. Next, samples were placed in an ultrasonic bath to help disperse silt and clay (mud) from sand and larger-sized particles. Samples were then rinsed twice in deionized water with centrifugation to remove soluble ions. Subsequently, the samples were wet sieved with 1 millimeter and 0.063 millimeter sieves to segregate the combined gravel and coarse sand fraction (greater than 1 millimeter), sand (1 millimeter to 0.063 millimeter), and mud (less than 0.063 millimeter). The coarse sand + gravel fractions were then dried, dry sieved at 1/4phi intervals and weighed (Carver, 1971). The sand fraction was dried and weighed. The mud fraction was collected in a 1 liter graduated cylinder, 5 milliliters of at least 10 percent sodium hexametaphosphate (dispersant) were added, and deionized water was added to bring the total the volume to 1 liter. The mud + dispersant solution sat for at least 12 hours to ensure complete dispersion and to observe if flocculation occurred. Subsequently, a 20 milliliter aliquot was extracted from the graduated cylinder and dried to obtain the mud fraction weight normalized to a 1-liter basis. The mud and sand fractions were analyzed separately via the Beckman Coulter LS 13 320 with the aqueous liquid module attachment. All size fraction data were compiled and converted by the PCMSC sediment lab pcSDSZ program (Penscil, 2015) to a grain-size distribution at 1/4phi size intervals on a weight percent basis. Person who carried out this activity:
   

   Angela Tan

   U.S. Geological Survey, Pacific Coastal and Marine Science Center

   Physical Scientist

   2885 Mission Street

   Santa Cruz, CA
   

   831-460-7409 (voice)

   atan@usgs.gov

3. What similar or related data should the user be aware of?
   Beckman-Coulter, 2011, Instructions for Use: LS 13 320 Laser Diffraction Particle Size Analyzer.

   Online Links:

   • https://www.beckmancoulter.com/wsrportal/techdocs?docname=b05577ab.pdf

   Other_Citation_Details:

   Beckman-Coulter, 2011, Instructions for Use: LS 13 320 Laser Diffraction Particle Size Analyzer: Brea, Calif., Beckman-Coulter, 246 p.

   Carver, Robert E., 1971, Procedures in Sedimentary Petrology.

   Online Links:

   • https://tamug-ir.tdl.org/handle/1969.3/21450

   Other_Citation_Details:

   Carver, R.E., 1971, Procedures in Sedimentary Petrology: Wiley Interscience, New York: 49-94.

   Folk, Robert Louis, 1974, Petrology of Sedimentary Rocks.

   Online Links:

   • https://tamug-ir.tdl.org/handle/1969.3/21435

   Other_Citation_Details:

   Folk, R.L., 1974, Petrology of Sedimentary Rocks: Hemphill Publishing Co., Austin, TX, 182 p.

   Folk, Robert Louis, 1980, Petrology of Sedimentary Rocks.

   Online Links:

   • https://repositories.lib.utexas.edu/bitstream/handle/2152/22930/folkpetrology.pdf?sequence=3

   Other_Citation_Details:

   Folk, R.L., 1980, Petrology of Sedimentary Rocks: Hemphill Publishing Co., Austin, TX, 184 p.

   Penscil, Inc., 2015, pcSDSZ Sediment Size Analysis Software for Windows: Operation Manual Version 2.00.

   Other_Citation_Details:

   Penscil Inc., 2015, pcSDSZ Sediment Size Analysis Software for Windows: Operation Manual Version 2.00: Los Osos, Calif., 131 p.

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

1. How well have the observations been checked?
   For grain-size analyses, annual service tests and daily calibrations with reference standards ensured that the Beckman Coulter LS 13 320 operated within specifications. Each sample was analyzed three times by the instrument, and the data were averaged. In addition, a lab procedural duplicate was run with each batch of samples to ensure consistency and values were within 15 percent.
2. How accurate are the geographic locations?
   The horizontal positioning for vibracores was determined using a Sonardyne Ranger 2720 USBL with Lodestar AHARS equipped on the ROV Doc Ricketts.
3. How accurate are the heights or depths?
   No formal positional accuracy tests were conducted, nor were they applicable for this dataset.
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 rest of the metadata record carefully for additional details.
5. How consistent are the relationships among the observations, including topology?
   No formal logical accuracy tests were conducted

How can someone get a copy of the data set?

1. Who distributes the data set? (Distributor 1 of 1)
   
   U.S. Geological Survey - CMGDS

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov
2. What's the catalog number I need to order this data set? Sediment grainsize data are available in comma-delimited text file format (2020-633-FA_2021-636-FA_cores_grainsize.csv), accompanied by FGDC-compliant metadata
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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	comma separated value (.csv) file in format comma-delimited text Size: 0.147
     Network links:	https://doi.org/10.5066/P1JUTTAN

   • Cost to order the data: None

Who wrote the metadata?

Dates:

Last modified: 08-Jan-2026

Metadata author:

PCMSC Science Data Coordinator

U.S. Geological Survey, Pacific Coastal and Marine Science Center

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)