Locations and grain-size analysis results of sediment samples collected in May and June 2023 using the SEABOSS 2.0 in Nantucket Sound, Massachusetts, in the vicinity of Horseshoe Shoal, by the U.S. Geological Survey during field activity 2023-001-FA (point shapefile and CSV file, GCS WGS 84)

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What does this data set describe?

Title:

Locations and grain-size analysis results of sediment samples collected in May and June 2023 using the SEABOSS 2.0 in Nantucket Sound, Massachusetts, in the vicinity of Horseshoe Shoal, by the U.S. Geological Survey during field activity 2023-001-FA (point shapefile and CSV file, GCS WGS 84)

Abstract:

In May and June 2023, the U.S. Geological Survey, in collaboration with the Massachusetts Office of Coastal Zone Management, collected high-resolution geophysical and seafloor sampling data, in Nantucket Sound to understand the regional geology in the vicinity of Horseshoe Shoal. Geophysical data collected include swath bathymetry, backscatter, and seismic reflection profile data. Ground-truth data, including sediment samples, underwater video, and bottom photographs were also collected. This effort is part of a long-term collaboration between the USGS and the Commonwealth of Massachusetts to map the State’s waters. In addition to resolving coastal hazards, habitats and resources, these data can be used to better understand the Quaternary history of coastal Massachusetts including the influence of sea-level change and sediment supply on coastal evolution. This collaboration produces high-resolution geologic data that serve the needs of research, management, and the public. Data collected as part of this mapping cooperative continue to be released in a series of USGS Reports and Data Releases https://www.usgs.gov/centers/whcmsc/science/geologic-mapping-massachusetts-seafloor

Supplemental_Information:

See the larger work citation to view the sea-floor videos, locations of bottom video tracklines, locations and grain-size analysis results of sediment samples, and geophysical survey data collected during the field activity. Support for field activity 2023-001-FA was provided to the USGS by the Massachusetts Office of Coastal Zone Management. For more information on the field activities associated with this project, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2022-001-FA and https://cmgds.marine.usgs.gov/fan_info.php?fan=2023-001-FA

How might this data set be cited?
Ackerman, Seth D., 20260521, Locations and grain-size analysis results of sediment samples collected in May and June 2023 using the SEABOSS 2.0 in Nantucket Sound, Massachusetts, in the vicinity of Horseshoe Shoal, by the U.S. Geological Survey during field activity 2023-001-FA (point shapefile and CSV file, GCS WGS 84): data release DOI:10.5066/P14NWTX8, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.
Online Links:
- https://doi.org/10.5066/P14NWTX8
- https://www.sciencebase.gov/catalog/item/68badfebd4be0209bab077e0
This is part of the following larger work.
Andrews, Brian D., Baldwin, Wayne E., Ackerman, Seth D., Worley, Charles R., Moore, Eric M., Nichols, Alex R., Berube, Patrick J., Huntley, Emily C., and Brothers, Laura L., 2026, High-resolution geophysical and sampling data collected in Nantucket Sound Massachusetts in the vicinity of Horseshoe Shoal, during USGS Field Activity 2023-001-FA: data release DOI:10.5066/P14NWTX8, U.S. Geological Survey, Reston, VA.
Online Links:
- https://doi.org/10.5066/P14NWTX8
- https://www.sciencebase.gov/catalog/item/68adc403d4be027f635b3f90
Other_Citation_Details:
Suggested citation: Andrews, B.D., Baldwin, W.E., Ackerman, S.D., Worley, C.R., Moore, E.M., Nichols, A.R., Berube, P.J., Huntley, E.C., and Brothers, L.L., 2026, High-resolution geophysical and sampling data collected in Nantucket Sound Massachusetts in the vicinity of Horseshoe Shoal, during USGS Field Activity 2023-001-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P14NWTX8
What geographic area does the data set cover?
West_Bounding_Coordinate: -70.47943085
East_Bounding_Coordinate: -70.29029622
North_Bounding_Coordinate: 41.57544647
South_Bounding_Coordinate: 41.50332379
What does it look like?

https://www.sciencebase.gov/catalog/file/get/68badfebd4be0209bab077e0?name=2023-001-FA_samples_browse.jpg (JPEG)
Thumbnail image of the sediment sample locations in the survey area in Nantucket Sound, Massachusetts.
Does the data set describe conditions during a particular time period?

Beginning_Date: 12-May-2023

Ending_Date: 14-Jun-2023

Currentness_Reference:

Data were collected on the following dates: 20230512, 20230613, and 20230614.
What is the general form of this data set?
Geospatial_Data_Presentation_Form: vector and tabular digital data
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):
  - Entity point (59)
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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
  The ellipsoid used is WGS_1984.
  The semi-major axis of the ellipsoid used is 6378137.000000.
  The flattening of the ellipsoid used is 1/298.257224.

How does the data set describe geographic features?

2023-001-FA_samples.csv

The CSV file created from the XLSX file provided by the USGS Sediment Laboratory. This file contains the grain size analysis results for sample submission SA14, analyzed using the Horiba laser diffraction unit and sieving of the ≥ -2 phi fraction. Note the sample depths were updated as described in Process Step 6. (Source: U.S. Geological Survey)

ANALYSIS_ID

An identifier for the sample which is unique to the database. This identifier begins with the assigned multi-letter code GS-, which corresponds to the type of analysis performed on the sample (grain size analysis), followed by a six-digit number assigned sequentially as samples are registered for analysis. (Source: U.S. Geological Survey) Character set

SAMPLE_ID

The identification value assigned to the sample at the time of collection. This varies from field activity to field activity and the ID can contain any combination of letters and numbers. (Source: U.S. Geological Survey) Character set

PROJECT

Name of project or project number under which samples were taken or data generated; sometimes project name indicates a more specific area. (Source: U.S. Geological Survey) Character set

FAN

The serial number assigned to the dataset field activity from which the sample belongs. This value is in the format YYYY-XXX-FA where YYYY is the year, XXX is the number assigned to the activity within the year, and FA indicates Field Activity. (Source: U.S. Geological Survey) Character set

SUBMITTER

Name of Principal investigator or chief scientist responsible for data collection, or researcher submitting samples for analysis (usually first initial and last name). (Source: U.S. Geological Survey) Character set

AREA

General geographic area of data collection. Name is general enough to easily locate area on a map. (Source: U.S. Geological Survey) Character set

LATITUDE

Latitude coordinate, in decimal-degrees, of sample location. South latitude recorded as negative values. (Source: U.S. Geological Survey)

Range of values
Minimum:	41.50332379
Maximum:	41.57544647
Units:	decimal degrees
Resolution:	0.0000001

LONGITUDE

Longitude coordinate, in decimal degrees, of sample location. West longitude is recorded as negative values. (Source: U.S. Geological Survey)

Range of values
Minimum:	-70.47943085
Maximum:	-70.29029622
Units:	decimal degrees
Resolution:	0.0000001

DEPTH_M

Measured depth of water overlying sediment at sample time, generally not corrected for tides, in meters. Entries with no depth indicated are left blank. (Source: U.S. Geological Survey)

Range of values
Minimum:	-28.7
Maximum:	-4.0
Units:	meters
Resolution:	0.1

T_DEPTH

Top depth of the sample below the sediment-water interface, in centimeters. Entries with no depth indicated are left blank. (Source: U.S. Geological Survey)

Range of values
Minimum:	0
Maximum:	0
Units:	centimeters
Resolution:	1

B_DEPTH

Bottom depth of the sample below the sediment-water interface, in centimeters. Entries with no depth indicated are left blank. (Source: U.S. Geological Survey)

Range of values
Minimum:	2
Maximum:	2
Units:	centimeter
Resolution:	1

DEVICE

Device used to collect the sample. Below lists all possible sample collection devices, please note that all devices may not be present in the table. Entries with no device indicated are left blank. (Source: U.S. Geological Survey)

Value	Definition
SEABOSS 2.0	Collection device name provided by the sample submitter.

DATE COLLECTED

Calendar date indicating when the sample was collected in the format MM/DD/YYYY where DD is the day of the month, MM is the numeric month, and YYYY is the year. Entries with no date indicated are left blank. (Source: U.S. Geological Survey) Character set

ANALYSIS COMPLETION DATE

Calendar date indicating when analyses on the sample were completed in the format MM/DD/YYYY where DD is the day of the month, MM is the numeric month, and YYYY is the year. (Source: U.S. Geological Survey) Character set

WEIGHT

Weight of initial sample in grams. (Source: U.S. Geological Survey)

Range of values
Minimum:	7.0335
Maximum:	31.4686
Units:	grams
Resolution:	.0001

GRAVEL_PCT

Gravel content in percent dry weight of the sample (particles with nominal diameters greater than 2 mm; -1 phi and larger). (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	57.2461
Units:	weight percent
Resolution:	.0001

SAND_PCT

Sand content in percent dry weight of the sample (particles with nominal diameters less than 2 mm, but greater than or equal to 0.0625 mm; 0 phi through 4 phi). (Source: U.S. Geological Survey)

Range of values
Minimum:	18.8427
Maximum:	100.004
Units:	weight percent
Resolution:	.0001

SILT_PCT

Silt content in percent dry weight of the sample (particles with nominal diameters less than 0.0625 mm, but greater than or equal to 0.004 mm; 5 phi through 8 phi, inclusive). (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	37.8213
Units:	weight percent
Resolution:	.0001

CLAY_PCT

Clay content in percent dry weight of the sample (particles with nominal diameters less than 0.004 mm; 9 phi and smaller). (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	12.2545
Units:	weight percent
Resolution:	.0001

CLASSIFICATION (Shepard)

Sediment classification - Sediment description based on a rigorous definition according to Shepard (1954) as modified by Schlee and Webster (1967), Schlee (1973), and Poppe and others (2014). Below lists all possible sediment classifications, please note that all classifications may not be present in the table. (Source: Shepard, F.P., 1954; Schlee, J.S., and Webster, Jacqueline, 1967; Schlee, J.S., 1973; Poppe, L.J., McMullen, K.Y., Williams, S.J., and Paskevich, V.F., 2014.)

Value	Definition
bedrock	Solid rock.
boulders	Rocks with diameters greater than 256 mm.
clay	Sediment whose main phase is less than 0.004 mm.
clayey sand	Sediment whose main phase is sand, but with significant clay.
clayey silt	Sediment whose main phase is silt, but with significant clay.
gravel	Sediment whose main phase is >2 mm.
gravelly sediment	Sediment whose main phase is >2 mm, but with significant other sediment. Gravel > 10 percent.
sand	Sediment whose main phase is less than 2 mm, but greater than or equal to 0.062 mm.
sand silt clay	Sediment with significant (over 20 percent) sand, silt, and clay.
sandy clay	Sediment whose main phase is clay, but with significant sand.
sandy silt	Sediment whose main phase is silt, but with significant sand.
silt	Sediment whose main phase is less than 0.0625 mm, but greater than or equal to 0.004 mm.
silty clay	Sediment whose main phase is clay, but with significant silt.
silty sand	Sediment whose main phase in sand, but with significant silt.
mud	Sediment whose main phase is less than 0.0625 mm
muddy sand	Sediment whose main phase is sand, but with significant silt and clay.

MEAN [Method of Moments Statistics - Logarithmic (φ)]

Average value in the grain size distribution in phi units. (Source: U.S. Geological Survey)

Range of values
Minimum:	-0.6314
Maximum:	2.6544
Units:	phi
Resolution:	.0001

STDEV [Method of Moments Statistics - Logarithmic (φ)]

Standard deviation (root mean square of the deviations) of the grain size distribution in phi units (sorting). (Source: U.S. Geological Survey)

Range of values
Minimum:	0.5506
Maximum:	4.5989
Units:	phi
Resolution:	.0001

SKEWNESS [Method of Moments Statistics - Logarithmic (φ)]

Skewness (unitless deviation from symmetrical form) of the grain size distribution in phi units. (Source: U.S. Geological Survey)

Range of values
Minimum:	-1.5099
Maximum:	3.4657
Units:	phi
Resolution:	.0001

KURTOSIS [Method of Moments Statistics - Logarithmic (φ)]

Kurtosis (unitless degree of curvature near the mode) of the grain size distribution in phi units. (Source: U.S. Geological Survey)

Range of values
Minimum:	1.4292
Maximum:	24.3815
Units:	phi
Resolution:	.0001

D10 [Method of Moments Statistics - Logarithmic (φ)]

Diameter at which 10% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	1.3144
Maximum:	8.4702
Units:	phi
Resolution:	.0001

D25 [Method of Moments Statistics - Logarithmic (φ)]

Diameter at which 25% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.8528
Maximum:	5.5344
Units:	phi
Resolution:	.0001

MEDIAN (D50) [Method of Moments Statistics - Logarithmic (φ)]

Diameter at which 50% of the sample mass is comprised of sediment particles with a diameter less than this value and 50% is larger; middle point in the grain size distribution in phi units. (Source: U.S. Geological Survey)

Range of values
Minimum:	-4.0748
Maximum:	3.1202
Units:	phi
Resolution:	.0001

D75 [Method of Moments Statistics - Logarithmic (φ)]

Diameter at which 75% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	-4.5374
Maximum:	1.5774
Units:	phi
Resolution:	.0001

D90 [Method of Moments Statistics - Logarithmic (φ)]

Diameter at which 90% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	-4.815
Maximum:	1.1852
Units:	phi
Resolution:	.0001

MEAN [Method of Moments Statistics - Arithmetic (μm)]

Average value in the grain size distribution in microns. (Source: U.S. Geological Survey)

Range of values
Minimum:	243.5685
Maximum:	12630.0164
Units:	microns
Resolution:	.0001

STDEV [Method of Moments Statistics - Arithmetic (μm)]

Standard deviation (root mean square of the deviations) of the grain size distribution in microns (sorting). (Source: U.S. Geological Survey)

Range of values
Minimum:	105.9895
Maximum:	11017.6954
Units:	microns
Resolution:	.0001

SKEWNESS [Method of Moments Statistics - Arithmetic (μm)]

Skewness (unitless deviation from symmetrical form) of the grain size distribution in microns. (Source: U.S. Geological Survey)

Range of values
Minimum:	-0.2275
Maximum:	9.0069
Units:	microns
Resolution:	.0001

KURTOSIS [Method of Moments Statistics - Arithmetic (μm)]

Kurtosis (unitless degree of curvature near the mode) of the grain size distribution in microns. (Source: U.S. Geological Survey)

Range of values
Minimum:	1.0848
Maximum:	98.8005
Units:	microns
Resolution:	.0001

D10 [Method of Moments Statistics - Arithmetic (μm)]

Diameter at which 10% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	3.1315
Maximum:	477.8932
Units:	microns
Resolution:	.0001

D25 [Method of Moments Statistics - Arithmetic (μm)]

Diameter at which 25% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	22.2607
Maximum:	581.9219
Units:	microns
Resolution:	.0001

MEDIAN (D50) [Method of Moments Statistics - Arithmetic (μm)]

Diameter at which 50% of the sample mass is comprised of sediment particles with a diameter less than this value and 50% is larger; middle point in the grain size distribution in microns. (Source: U.S. Geological Survey)

Range of values
Minimum:	124.5854
Maximum:	17196.1763
Units:	microns
Resolution:	.0001

D75 [Method of Moments Statistics - Arithmetic (μm)]

Diameter at which 75% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	310.5243
Maximum:	24598.0881
Units:	microns
Resolution:	.0001

D90 [Method of Moments Statistics - Arithmetic (μm)]

Diameter at which 90% of the sample mass is comprised of sediment particles with a diameter less than this value. (Source: U.S. Geological Survey)

Range of values
Minimum:	395.2083
Maximum:	29039.2353
Units:	microns
Resolution:	.0001

PHI_16

16 phi: weight percent of the sample in the 16 phi fraction and smaller (nominal diameter of particles greater than or equal to 0.000015625 mm, less than 0.00003125 mm); colloid. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	0.0
Units:	weight percent
Resolution:	.001

PHI_15

15 phi: weight percent of the sample in the 15 phi fraction (nominal diameter of particles greater than or equal to 0.00003125 mm, less than 0.0000625 mm); colloid. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	0.0
Units:	weight percent
Resolution:	.001

PHI_14

14 phi: weight percent of the sample in the 14 phi fraction (nominal diameter of particles greater than or equal to 0.0000625 mm, less than 0.000125 mm); colloid. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	0.0
Units:	weight percent
Resolution:	.001

PHI_13

13 phi: weight percent of the sample in the 13 phi fraction (nominal diameter of particles greater than or equal to 0.000125 mm, less than 0.00025 mm); fine clay. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	0.0
Units:	weight percent
Resolution:	.001

PHI_12

12 phi: weight percent of the sample in the 12 phi fraction (nominal diameter of particles greater than or equal to 0.00025 mm, but less than 0.0005 mm); fine clay. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	3.191
Units:	weight percent
Resolution:	.001

PHI_11

11 phi: weight percent of the sample in the 11 phi fraction (nominal diameter of particles greater than or equal to 0.0005 mm, but less than 0.001 mm); fine clay. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	2.49
Units:	weight percent
Resolution:	.001

PHI_10

10 phi: weight percent of the sample in the 10 phi fraction (nominal diameter of particles greater than or equal to 0.001 mm, but less than 0.002 mm); medium clay. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	1.824
Units:	weight percent
Resolution:	.001

PHI_9

9 phi: weight percent of the sample in the 9 phi fraction (nominal diameter of particles greater than or equal to 0.002 mm, but less than 0.004 mm); coarse clay. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	4.749
Units:	weight percent
Resolution:	.001

PHI_8

8 phi: weight percent of the sample in the 8 phi fraction (nominal diameter of particles greater than or equal to 0.004 mm, but less than 0.008 mm); very fine silt. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	4.968
Units:	weight percent
Resolution:	.001

PHI_7

7 phi: weight percent of the sample in the 7 phi fraction (nominal diameter of particles greater than or equal to 0.008 mm, but less than 0.016 mm); fine silt. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	14.936
Units:	weight percent
Resolution:	.001

PHI_6

6 phi: weight percent of the sample in the 6 phi fraction (nominal diameter of particles greater than or equal to 0.016 mm, but less than 0.031 mm); medium silt. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	10.298
Units:	weight percent
Resolution:	.001

PHI_5

5 phi: weight percent of the sample in the 5 phi fraction (nominal diameter of particles greater than or equal to 0.031 mm, but less than 0.0625 mm); coarse silt. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	7.619
Units:	weight percent
Resolution:	.001

PHI_4

4 phi: weight percent of the sample in the 4 phi fraction (nominal diameters of particles greater than or equal to .0625 mm, but less than 0.125 mm); very fine sand. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	13.501
Units:	weight percent
Resolution:	.001

PHI_3

3 phi: weight percent of the sample in the 3 phi fraction (nominal diameter of particles greater than or equal to 0.125 mm, but less than 0.25 mm); fine sand. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.283
Maximum:	48.55
Units:	weight percent
Resolution:	.001

PHI_2

2 phi: weight percent of the sample in the 2 phi fraction (nominal diameter of particles greater than or equal to 0.25 mm, but less than 0.5 mm); medium sand. (Source: U.S. Geological Survey)

Range of values
Minimum:	3.305
Maximum:	70.336
Units:	weight percent
Resolution:	.001

PHI_1

1 phi: weight percent of the sample in the 1 phi fraction (nominal diameter of particles greater than or equal to 0.5 mm, but less than 1 mm); coarse sand. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	71.725
Units:	weight percent
Resolution:	.001

PHI_0

0 phi: weight percent of the sample in the 0 phi fraction (nominal diameters of particles greater than or equal to 1 mm, but less than 2 mm); very coarse sand. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	14.158
Units:	weight percent
Resolution:	.001

PHI_-1

-1 phi: weight percent of the sample in the -1 phi fraction (nominal diameter of particles greater than or equal to 2 mm, but less than 4 mm); very fine pebbles (granules). (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	0.782
Units:	weight percent
Resolution:	.001

PHI_-2

-2 phi: weight percent of the sample in the -2 phi fraction (nominal diameter of particles greater than or equal to 4 mm, but less than 8 mm); fine pebbles. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	21.447
Units:	weight percent
Resolution:	.001

PHI_-3

-3 phi: weight percent of the sample in the -3 phi fraction (nominal diameter of particles greater than or equal to 8 mm, but less than 16 mm); medium pebbles. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	27.139
Units:	weight percent
Resolution:	.001

PHI_-4

-4 phi: weight percent of the sample in the -4 phi fraction (nominal diameter of particles greater than or equal to 16 mm, but less than 32 mm); coarse pebbles. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	54.04
Units:	weight percent
Resolution:	.001

PHI_-5

-5 phi: weight percent of the sample in the -5 phi fraction (nominal diameter of particles greater than or equal to 32 mm, but less than 64 mm); very coarse pebbles. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	0.0
Units:	weight percent
Resolution:	.001

PHI_-6

-6 phi: weight percent of the sample in the -6 phi fraction and larger (nominal diameter of particles greater than or equal to 64 mm, but less than 128 mm); cobbles. (Source: U.S. Geological Survey)

Range of values
Minimum:	0.0
Maximum:	0.0
Units:	weight percent
Resolution:	.001

ANALYST

Name (usually first, middle, and last initials) of person who performed the grain size or physical properties analysis. (Source: U.S. Geological Survey) Character set

QUALITY GRADE

Samples are assigned a quality grade based on the examination of the analytical data. Data quality grades may be determined by several factors, such as consistency with samples collected from a geospatially adjacent location and consistencybetween replicate runs, and any comments or notes that indicate the data for a particular sample may be suspect are included in the results table for that sample under "comments". When considering replicate run values, if there is over a 10% difference between relative fraction percentages in this sample and the replicate, a quality grade of B will be assigned, over 15% would be assigned a C, and over 20% would be assigned a D. Quality grades for sample data that do not have any additional comments are assigned based on the calculated percent difference between the weights of the coarse fraction remaining after wet sieving and the sum of all of the weighed fractions after dry sieving the coarse fraction, indicating an estimated differing amount of material which could skew the calculated grain size results: A = percent differences between 0% and ±1.5%, B = percent differences between ±1.5% and ±3%, C = percent differences between ±3% and ±4.5%, and D = percent differences greater than ±4.5%. The quality grade is followed by a hyphen and the initials of the person who assigned the grade: BJB is Brian J Buczkowski; JDC is Jason D Chaytor; SJW is Sarah J Widlansky. (Source: U.S. Geological Survey)

Value	Definition
A	percent differences between 0% and ±1.5%, there is less than 10% difference in relative fraction percentages between this sample and the replicate, or the results are consistent with expected values.
B	percent differences between ±1.5% and ±3%, there is greater than 10% and less than 15% difference in relative fraction percentages between this sample and the replicate, or the results are generally consistent with expected values.
C	percent differences between ±3% and ±4.5%, there is greater than 15% and less than 20% difference in relative fraction percentages between this sample and the replicate, or the results are somewhat consistent with expected values.
D	percent differences greater than ±4.5%, there is greater than 20% difference in relative fraction percentages between this sample and the replicate, or the results are inconsistent with expected values.

Character set

2023-001-FA_samples.shp

The shapefile, containing 59 point features, has a subset of the fields from the grain-size analysis results CSV file (2023-001-FA_samples.csv). Specifically, the diameter Method of Moments Statistics (e.g. D10) and the individual phi measurements (e.g., PHI_13) were removed. The shapefile also has two additional attributes, FID and Shape, which have the following descriptions: Attribute: Attribute Label: FID Attribute Definition: Internal feature number. Attribute Definition Source: Esri Attribute Domain Values: Unrepresentable Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute Label: Shape Attribute Definition: Feature geometry. Attribute Definition Source: Esri Attribute Domain Values: Unrepresentable Domain: Coordinates defining the features. All the other attributes in the shapefile have the same definitions as the CSV file attributes (see the Detailed Description section above for 2023-001-FA_samples.csv for definitions of the file attributes). Please note that some of the field names were truncated since a shapefile field name can only contain up to 10 characters: ANALYSIS_I (truncated field name for ANALYSIS_ID), DATE_COLLE (truncated field name for DATE_COLLECTED), ANALYSIS_C (truncated field name for ANALYSIS_COMPLETION_DATE), and CLASSIFICA (truncated field name for CLASSIFICATION). (Source: U.S. Geological Survey)

Entity_and_Attribute_Overview:

The CSV file contains the sediment analyses as received from the sediment lab (but with the updated depth data). The column headers of CSV file is slightly modified from the original data provided by the sediment laboratory in order to enable import into GIS software. The shapefile is a simplified version of the sediment lab analyses (see the Entity Type Definition for more details).

Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
- Seth D. Ackerman
Who also contributed to the data set?
To whom should users address questions about the data?

Seth Ackerman

U.S. Geological Survey

Geologist

384 Woods Hole Rd.
Woods Hole, MA

USA

508-548-8700 x2315 (voice)

508-457-2310 (FAX)

sackerman@usgs.gov

Why was the data set created?

These data were collected to characterize the sea floor by identifying sediment texture and to ground-truth acoustic data collected during the both 2022-001-FA, and 2023-001-FA. This dataset contains the locations and grain-size analysis results of surficial sediments collected with a modified Van Veen grab sampler on the SEABed Observation and Sampling System (SEABOSS 2.0). Fifty-nine sediment samples were acquired at 60 sampling locations covering both the 2022-001-FA, and 2023-001-FA survey areas in Nantucket Sound. The SEABOSS 2.0 is equipped with a FLIR Blackfly S BFS-PGE-50S5M-C camera, a DeepSea Power & Light HD Multi SeaCam video camera and a modified Van Veen grab sampler and was deployed from the Research Vessel (R/V) Rafael during USGS field activity 2023-001-FA (May 12 and June 13-14, 2023). These data were collected to characterize the sea floor by identifying sediment texture and to ground-truth acoustic data collected during the field activity. The sediments were analyzed using the Horiba laser diffraction unit (LA-960) and sieving of the ≥ -2 phi fraction.

How was the data set created?

From what previous works were the data drawn?
How were the data generated, processed, and modified?
Date: 14-Jun-2023 (process 1 of 6)
STEP 1: COLLECTED DATA. A marine geophysical and sampling survey (field activity 2023-001-FA) was conducted in Nantucket Sound, Massachusetts, in the vicinity of Horseshoe Shoal in May and June 2023. The ground validation data was collected while the R/V Rafael occupied one of the target sites, and the SEABOSS 2.0 was deployed off the vessel's portside. The SEABOSS was equipped with a modified Van Veen grab sampler, a FLIR Blackfly S BFS-PGE-50S5M-C digital camera with a topside feed, an oblique downward-looking DeepSea Power & Light HD Multi SeaCam video camera with a topside feed, and DeepSea Power & Light LED SeaLites to illuminate the sea floor for video and photograph collection. The elements of this particular SEABOSS were held within a stainless-steel frame that measured ~1 x 1 meter. The frame had a stabilizer fin that oriented the system as it drifted over the seabed. Two red lasers were set 20 centimeters apart (both as they were mounted on the SEABOSS frame and as seen in photographs and video on the seabed) for scale measurements. The red laser dots can usually be seen in the sea-floor photos and videos depending on the bottom type, water clarity, and distance to the sea floor. The winch operator lowered the SEABOSS until the sea floor was observed in the topside live video feed. Generally, the vessel and SEABOSS drifted with wind and current for up to a few minutes to ensure a decent photo with a clear view of the sea floor was acquired. A scientist monitored the real-time bottom video and acquired bottom photographs at points of interest by remotely triggering the FLIR camera shutter. The photographed area is most often within 0.5 to 1.25 meters from left to right. Bottom video was also recorded during the drift from the oblique downward-looking DeepSea Power & Light HD Multi SeaCam video camera directly to a solid-state drive using an Odyssey7 video recorder. Due to equipment overheating issues, the FLIR camera stopped working after site 2023-001-050, so still-image frame grabs were captured from the DeepSea Power & Light bottom videos for the last 10 sites (sites 2023-001-051 through 2023-001-060) described in a subsequent process step. After drifting for up to a few minutes, the winch operator lowered the SEABOSS sampler until it rested on the sea floor. When the system was raised, the Van Veen grab sampler closed and collected a sample as it was lifted off the sea floor. The sampler was recovered to the deck of the survey vessel where a subsample was taken for grain-size analysis at the sediment laboratory at the USGS Woods Hole Coastal and Marine Science Center. During the survey, DGPS navigation from a Hemisphere R131 DGPS receiver (see Positional_Accuracy statement above for more info). Dates and times were recorded in UTC. When the FLIR camera shutter was remotely triggered to take a photo, the photo filename and navigation data for that timestamp were saved to a CSV file, which was used to geotag the images in a subsequent process step. The DGPS data were also overlaid onto the video using a Proteus-V Pro video overlay device. A survey log was maintained during the field activity by the technical and scientific staff as an Excel spreadsheet. It contains information about bottom photo and video acquisition, sediment sampling, and other miscellaneous notes from the survey. A total of 59 sediment samples were collected using the SEABOSS 2.0 at 60 sites during field activity 2023-001-FA. Bottom imagery was collected at all 60 sites. Person who carried out this activity:

Seth Ackerman

U.S. Geological Survey

Geologist

384 Woods Hole Rd.
Woods Hole, MA

USA

508-548-8700 x2315 (voice)

508-457-2310 (FAX)

sackerman@usgs.gov

Data sources produced in this process:
- Original FLIR TIFF photographs
- DeepSea Power & Light bottom videos
- Survey log
- Photo navigation CSV files Survey log
- Raw navigation data
- Sediment samples
Date: 18-Jul-2023 (process 2 of 6)
STEP 2: ASSEMBLED SAMPLE INFORMATION FOR SEDIMENT LABORATORY. The sediment sample times (as recorded in the survey log) were checked by viewing the bottom videos to see when the sampler was lifted off the sea floor at each site and updated with more precise times as appropriate. The latitude and longitude from the video overlay at the time of the sample were also noted for each sediment sample. Sites from the survey day in May had no video overlay so the sample time as recorded on that day was correlated to the ship's navigation log to determine the GPS position. Depths for each sample were extracted from a composite bathymetry dataset for coastal Massachusetts. These depths were updated from a bathymetry grid of the newer data from this mapping program (field activities 2022-001-FA and 2023-001-FA (see Process Step 5). This information was then provided to the sediment laboratory at the USGS Woods Hole Coastal and Marine Science Center with the sample analysis request form for the survey. Person who carried out this activity:

Seth Ackerman

U.S. Geological Survey

Geologist

384 Woods Hole Rd.
Woods Hole, MA

USA

508-548-8700 x2315 (voice)

508-457-2310 (FAX)

sackerman@usgs.gov

Data sources used in this process:
- Survey log
- Bottom videos
- Composite bathymetry
Data sources produced in this process:
- Survey log with updated sample times
- Sediment sample locations CSV file
Date: May-2024 (process 3 of 6)
STEP 3: SAMPLE ANALYSIS Samples submitted to the Sediment Laboratory for grain size analysis using the Horiba laser diffraction unit (LA-960) and sieving of the ≥ -2 phi fraction are assigned unique analysis identifiers (ANALYSIS_ID), and divided into batches of no more than 30 samples. Each batch is entered into a Microsoft Excel data entry spreadsheet (LD Worksheet Template_SA14.xlsx, where SA14 is the identifier assigned to the sample submission) to record the initial and dried sample weights, as well as the sieved coarse fraction weights. Each batch is also is entered into macro-enabled Microsoft Excel data entry spreadsheets (SA14_GrainSizeWorksheet_LD1-30.xlsm or SA14_GrainSizeWorksheet_LD31-60.xlsm, where SA14 is the identifier assigned to the sample submission, “LD1-30” and “LD31-60” refer to the pre-labeled and weighed glass laser diffraction vials the samples will be run in) to record the measurement data coming from the laser diffraction unit and incorporate the initial, dried, and sieved weights.About 5-10 grams of wet sediment or 3-5 grams of dry sediment are placed in a pre-weighed beaker and the gross weight is recorded. The sample is wet sieved through a 4 mm (No. 5) sieve. If there is any coarse fraction remaining in the sieve, the coarse material is oven dried at 100°C in a pre-weighed beaker, and weighed again when dry. This coarse fraction is dry sieved to determine the individual weights of the -2 to -5 phi fractions, and the weights are recorded in the data entry spreadsheet LD Worksheet Template_SA14.xlsx. The fine fraction in water is collected in a pre-labeled and weighed glass laser diffraction vial. If there is any coarse fraction remaining in the sieve from wet sieving, this vial is also oven dried at 100°C and weighed when dry. If there is no coarse fraction remaining from wet sieving, the sample can proceed directly to processing for analyses by the Horiba laser diffraction unit (LA-960).Fine fractions ready for analysis by the Horiba laser diffraction unit are rehydrated with distilled water if they’ve been dry. Fifteen (15) ml of pre-mixed 40 g/l sodium hexametaphosphate [(NaPO3)6] are added to each sample. If the height of the fluid in the laser diffraction vial is less than 5 cm, more distilled water is added to raise the level to no more than 8 cm in the vial. The samples are gently stirred, covered, and allowed to soak for at least 1 hour (for samples that were not dried) up to 24 hours (for samples that were dried). Soaked vials are placed into an ultrasonic bath and run for 10 minutes at a frequency of 37 Hz with a power level of 100. If the samples appear to be fully disaggregated, they are placed into pre-determined autosampler locations, and are run using the Horiba LA-960 for Windows software to get the fine fraction grain size distributions. The fine fraction distribution data are added to the appropriate data entry spreadsheets (SA14_GrainSizeWorksheet_LD1-30 or SA14_GrainSizeWorksheet_LD31-60.xlsm). The spreadsheet is used to calculate a continuous phi class distribution from the original fractions. Data from this submission were processed using version 2.3 of the data entry spreadsheet. Person who carried out this activity:

U.S. Geological Survey

Sediment Laboratory Manager

384 Woods Hole Road
Woods Hole, MA

USA

(508) 548-8700 (voice)

(508) 457-2310 (FAX)

Date: 16-May-2024 (process 4 of 6)
STEP 4: ADDITIONAL SAMPLE CALCULATIONS Continuous phi class distribution from the original fractions are transposed to the "results" tab in the macro-enabled Microsoft Excel data entry workbook (SA14_GrainSizeWorksheet_LD1-30.xlsm or SA14_GrainSizeWorksheet_LD31-60.xlsm, where SA14 is the identifier assigned to the sample submission, “LD1-30” and “LD31-60” refer to the pre-labeled and weighed glass laser diffraction vials the samples will be run in). Macros in the workbook (“GS_MoM_Arithmetic_1”, “GS_MoM_Arithmetic_2”, "GS_statistics", and "sedimentname") are run to calculate grain size classification and statistical analyses and finish processing the data. Sample, navigation, and field identifiers, along with continuous phi class distribution data, grain size classification, and statistical analysis results are copied and pasted into a final Microsoft Excel spreadsheet (SA14_GS-LD_results.xlsx, where SA14 is the batch number assigned to the sample submission). The processed data are quality control checked and assigned a quality grade based on the examination of the analytical data. Processed data are released to the submitter and incorporated into the laboratory's database. All raw analytical data generated by the samples are archived in the Sediment Laboratory. Person who carried out this activity:

U.S. Geological Survey

Sediment Laboratory Manager

384 Woods Hole Road
Woods Hole, MA

USA

(508) 548-8700 (voice)

(508) 457-2310 (FAX)

gs-wh_sedlab@usgs.gov

Date: 09-Aug-2024 (process 5 of 6)
STEP 5: CONVERT XLSX TO CSV AND SHAPEFILE The sediment laboratory Excel spreadsheet was saved as a CSV file, column headers were modified, and the CSV file was imported into QGIS (version 3.34.7) as a delimited text layer. The resulting spatial dataset was saved as an Esri shapefile format. Person who carried out this activity:

Seth Ackerman

U.S. Geological Survey

Geologist

384 Woods Hole Rd.
Woods Hole, MA

USA

508-548-8700 x2315 (voice)

508-457-2310 (FAX)

sackerman@usgs.gov

Date: 11-Sep-2025 (process 6 of 6)
STEP 6: UPDATE DEPTHS New depths for each sample were extracted from a composite bathymetry created from the bathymetry grid in this publication and from survey 2022-001-FA (2022_2023_NtktSnd_Merge_MLLW_2m.tif) using the geoprocessing tool "Sample Raster Values" in QGIS 3.34.7. A new final shapefile was exported. Depths were also updated in the XLXS and CSV files. The new depth data were provided back to the Sediment Laboratory to update these sample records in their database. Person who carried out this activity:

Seth Ackerman

U.S. Geological Survey

Geologist

384 Woods Hole Rd.
Woods Hole, MA

USA

508-548-8700 x2315 (voice)

508-457-2310 (FAX)

sackerman@usgs.gov
What similar or related data should the user be aware of?
Shepard, F.P., 1954, Nomenclature based on sand-silt-clay ratios: Journal of Sedimentary Petrology v. 24, no. 3., p. 151-158.

Schlee, J.S., and Webster, J., 1967, A computer program for grain-size data: Sedimentology v. 8, no. 1., p. 45-53.
Schlee, J.S., 1973, Atlantic continental shelf and slope of the United States-sediment texture of the northeastern part: Professional Paper 529-L, U.S. Geological Survey, Reston, VA.
Online Links:
- https://doi.org/10.3133/pp529L
Poppe, L.J., McMullen, K.Y., Williams, S.J., and Paskevich, V.F., 2014, USGS east-coast sediment analysis: Procedures, database, and GIS data: Open-File Report 2005-1001, U.S. Geological Survey, Reston, VA.
Online Links:
- https://pubs.usgs.gov/of/2005/1001/

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

How well have the observations been checked?
How accurate are the geographic locations?
The seafloor survey was conducted with the SEABOSS 2.0 system, and the sampling site locations were recorded . This was done by populating the metadata of each image with coordinate data from the vessel's navigation system. The estimated horizontal positional accuracy of the bottom image locations is approximately 5 meters. This is a conservative estimate that accounts for the various sources of horizontal offsets and inaccuracies. Navigation Data and Processing: During field activity 2023-001-FA, Differential Global Positioning System (DGPS) navigation was used. For the May survey day, the DGPS was set to receive fixes at 4 hertz (Hz) or 4 records per second in geographic coordinates (Geographic Coordinate System [GCS] World Geodetic System of 1984 [WGS 84]). For the June survey days, the DGPS was set to receive fixes at 2 Hz or 2 records per second. A key factor of potential inaccuracy is the location of the recorded position. The coordinates embedded in each image's metadata correspond to the position of the DGPS antenna on the survey vessel, not the exact location of the SEABOSS on the seafloor. For the survey day in May, the DGPS antenna was located on the R/V Rafael's aft starboard side of the wheelhouse and for the June survey days the antenna was on the aft port side of the wheelhouse. In both cases, the antenna was approximately 2-3 meters from the SEABOSS deployment location. No layback or offset was applied to correct for this physical separation or for the SEABOSS potentially drifting away from the vessel when deployed to the seafloor. Data Management and Discrepancies: A comparison of the SEABOSS's DGPS and the ship's navigation data at three locations on the first day showed them to be less than one meter apart. It is important to note that the navigation data were processed differently for the bottom photos and the video tracklines, meaning these datasets may not always intersect exactly with the sample site location.
How accurate are the heights or depths?
Depths values recorded in the CSV and shapefile are referenced to MLLW tidal datum. Depths were extracted using the published locations of the samples and the published bathymetry grid from this publication and 2022-001-FA. See Processing Step 2 for details. In general the vertical accuracy of the bathymetry is approximately 1 percent of water depth. However, any inaccuracies in the vertical component are far outweighed by the inaccuracies inherent in the method used to record the x,y coordinates of the sample as described above.
Where are the gaps in the data? What is missing?
This dataset includes a Comma Separated Values (CSV) file and a shapefile of the locations and grain-size analysis results of the sediment samples collected during field activity 2023-001-FA. The shapefile contains a subset of the grain-size analysis results, so users should access the CSV file for the full sediment grain-size analysis results. Physical sediment samples were collected at 59 of the 60 sites occupied during field activity 2023-001-FA; there was no sample collected at site 2023-001-006.
How consistent are the relationships among the observations, including topology?
These data were checked but no modifications or corrections have been made to the file.

How can someone get a copy of the data set?

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

Access_Constraints	No access constraints. Please see 'Distribution Information' for details.
Use_Constraints	These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations.

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

U.S. Geological Survey - ScienceBase

Denver Federal Center
Denver, CO

1-888-275-8747 (voice)

sciencebase@usgs.gov
What's the catalog number I need to order this data set? Downloadable Data. Locations and grain-size analysis results of sediment samples collected in Nantucket Sound, Massachusetts, in the vicinity of Horseshoe Shoal in May and June 2023 by the U.S. Geological Survey during field activity 2023-001-FA. This dataset contains the following files: a CSV version of the sediment laboratory analyses and a shapefile with a subset of the sediment analyses.
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. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

How can I download or order the data?

Availability in digital form:

Data format:

This dataset contains a CSV file of locations and grain-size analysis results for sediment samples collected by the U.S. Geological Survey in Nantucket Sound, Massachusetts, in the vicinity of Horseshoe Shoal in May and June 2023 by the U.S. Geological Survey during field activity 2023-001-FA. The transfer size of the CSV file is 0.026 MB. in format Comma-delimited text (version Microsoft Excel 2024) Comma Separated Values (CSV) text file Size: 0.026

Network links:

https://www.sciencebase.gov/catalog/item/68badfebd4be0209bab077e0
https://www.sciencebase.gov/catalog/file/get/68badfebd4be0209bab077e0
https://doi.org/10.5066/P14NWTX8

Data format:

This dataset contains an Esri format shapefile of locations and a subset of the grain-size analysis results for sediment samples collected by the U.S. Geological Survey in Nantucket Sound, Massachusetts, in the vicinity of Horseshoe Shoal in May and June 2023 by the U.S. Geological Survey during field activity 2023-001-FA. The transfer size of the shapefile file is 0.3 MB. in format Shapefile (version QGIS (version 3.34.7)) Esri Shapefile Size: 0.3

Network links:

https://www.sciencebase.gov/catalog/item/68badfebd4be0209bab077e0
https://www.sciencebase.gov/catalog/file/get/68badfebd4be0209bab077e0
https://doi.org/10.5066/P14NWTX8

Cost to order the data: none

What hardware or software do I need in order to use the data set?
This dataset contains data available as a point shapefile and a CSV file. The user must have software capable of reading shapefile format to use the point shapefile. The CSV file can be read with a text editor or any software capable of viewing tabular data.

Who wrote the metadata?

Dates:

Last modified: 21-May-2026

Metadata author:

Seth Ackerman

U.S. Geological Survey

Geologist

384 Woods Hole Rd.

Woods Hole, MA

USA

508-548-8700 x2315 (voice)

508-457-2310 (FAX)

whsc_data_contact@usgs.gov

Contact_Instructions:

The metadata contact email address is a generic address in the event the person is no longer with the USGS.

Metadata standard:

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

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P14NWTX8/2023-001-FA_samples_meta.faq.html>