Skip past header information
USGS - science for a changing world
NOAA Logo with link to NOAA Home Page.CT DEP Logo with link to CT DEP Home Page.  

U.S. Geological Survey Open-File Report 2010–1005

Surficial Geology of the Sea Floor in Long Island Sound Offshore of Plum Island, New York


Sediments

Skip past contents information
Click on figure for larger image
Thumbnail image of figure 10 and link to larger figure. A map showing station locations in the study area where photography and sediment samples were collected.
Figure 10. Location of stations in the study area where photography and sediment samples were collected during R/V Rafael cruise 09059.
Sediment Distribution

Sediment samples were taken from six stations in the study area to be analyzed for grain size and seven stations were classified as gravel based on visual observations using the small SEABOSS. The study area contains gravel, gravelly sediment, and sand, based on data from the 13 stations (fig. 10). Gravel and gravelly sediment are located in areas where boulders are visible in the bathymetry data and high-backscatter areas of the sidescan-sonar image. Sand was found in lower backscatter areas of the sidescan sonar and in areas where sand waves were visible. The lack of mud in the study area is likely due to strong currents that prevent fine-grained sediment from being deposited.

Sediment Data

The sediment grain-size dataset provided here contains information on the collection, location, description, and texture of sediments at 13 stations occupied during the 2009 R/V Rafael cruise 09059 (fig. 10). All analyses were conducted in the sedimentation laboratory at the USGS Woods Hole Coastal and Marine Science Center. Records without textural data and statistics are based on visual descriptions. The basic structure of the data is a flat-file format, a matrix where records are rows representing individual samples and the columns contain sample- and station-specific information. This matrix consists of 42 fields which are defined in the Data Dictionary below.

The sediment data are provided in two formats: Microsoft Excel and comma-delimited ASCII text format along with metadata in the Data Catalog section.

Data Dictionary

An integral part of any database is the dictionary that explains the structure and content. It contains a list of the fields and definitions of parameters measured. Data utilization is facilitated by reference to this compilation because it defines abbreviations and lists field names.

LABNO - Unique sample identifier assigned in the laboratory

STATIONID - Sample name or number assigned in the field

PROJECT - Project under which samples were taken or data generated

CRUISEID - Name or number of cruise on which sample was collected or station occupied

PRINCIPAL - Name of principal investigator

LATITUDE - Latitude in decimal degrees

LONGITUDE - Longitude in decimal degrees (west longitudes are negative values)

DEPTH_M - Depth of water measured by a hull-mounted fathometer overlying sediment at the time of sampling, not corrected for tides, in meters

T_DEPTH - Top depth of the sample below the sediment-water interface, in centimeters

B_DEPTH - Bottom depth of the sample below the sediment-water interface, in centimeters

DEVICE - Device used to collect the sample

MONTH - Number of calendar month during which the sample was collected

DAY - Calendar day on which the sample was collected

YEAR - Calendar year during which the sample was collected

WEIGHT - Dry weight of sample, in grams

ZGRAVEL - Gravel content in percent dry weight of the sample (particles with nominal diameters greater than 2 millimeters; -1 phi and larger)

ZSAND - Sand content in percent dry weight of the sample (particles with nominal diameters less than 2 millimeters but greater than or equal to 0.0625 millimeters; 0 through 4 phi, inclusive)

ZSILT - Silt content in percent dry weight of the sample (particles with nominal diameters less than 0.0625 millimeters but greater than or equal to 0.004 millimeters; 5 through 8 phi, inclusive)

ZCLAY - Clay content in percent dry weight of the sample (particles with nominal diameters less than 0.004 millimeters; 9 phi and smaller)

SEDCLASS - Sediment description based on a rigorous definition (Shepard, 1954)

MEDIAN - Middle point in the grain-size distribution, in phi units

MEAN - Average value in the grain-size distribution, in phi units

STDDEV - Standard deviation (root mean square of the deviations) of the grain-size distribution, in phi units (that is, sorting)

SKEWNESS - Deviation from symmetrical form of the grain-size distribution

KURTOSIS - Degree of curvature near the mode of the grain-size distribution

PHI _11 - Weight percent of the sample in the 11 phi fraction (nominal diameter of particles greater than or equal to 0.0005 millimeters but less than 0.001 millimeters); fine clay

PHI_10 - Weight percent of the sample in the 10 phi fraction (nominal diameter of particles greater than or equal to 0.001 millimeters but less than 0.002 millimeters); medium clay

PHI_9 - Weight percent of the sample in the 9 phi fraction (nominal diameter of particles greater than or equal to 0.002 millimeters but less than 0.004 millimeters); coarse clay

PHI_8 - Weight percent of the sample in the 8 phi fraction (nominal diameter of particles greater than or equal to 0.004 millimeters but less than 0.008 millimeters); very fine silt

PHI_7 - Weight percent of the sample in the 7 phi fraction (nominal diameter of particles greater than or equal to 0.008 millimeters but less than 0.016 millimeters); fine silt

PHI_6 - Weight percent of the sample in the 6 phi fraction (nominal diameter of particles greater than or equal to 0.016 millimeters but less than 0.031 millimeters); medium silt

PHI_5 - Weight percent of the sample in the 5 phi fraction (nominal diameter of particles greater than or equal to 0.031 millimeters but less than 0.0625 millimeters); coarse silt

PHI_4 - Weight percent of the sample in the 4 phi fraction (nominal diameters of particles greater than or equal to .0625 millimeters but less than 0.125 millimeters); very fine sand

PHI_3 - Weight percent of the sample in the 3 phi fraction (nominal diameter of particles greater than or equal to 0.125 millimeters but less than 0.25 millimeters); fine sand

PHI_2 - Weight percent of the sample in the 2 phi fraction (nominal diameter of particles greater than or equal to 0.25 millimeters but less than 0.5 millimeters); medium sand

PHI_1 - Weight percent of the sample in the 1 phi fraction (nominal diameter of particles greater than or equal to 0.5 millimeters but less than 1 millimeter); coarse sand

PHI_0 - Weight percent of the sample in the 0 phi fraction (nominal diameters of particles greater than or equal to 1 millimeter but less than 2 millimeters); very coarse sand

PHIM1 - Weight percent of the sample in the -1 phi fraction (nominal diameter of particles greater than or equal to 2 millimeters but less than 4 millimeters); very fine pebbles (granules)

PHIM2 - Weight percent of the sample in the -2 phi fraction (nominal diameter of particles greater than or equal to 4 millimeters but less than 8 millimeters); fine pebbles

PHIM3 - Weight percent of the sample in the -3 phi fraction (nominal diameter of particles greater than or equal to 8 millimeters but less than 16 millimeters); medium pebbles

PHIM4 - Weight percent of the sample in the -4 phi fraction (nominal diameter of particles greater than or equal to 16 millimeters but less than 32 millimeters); coarse pebbles

PHIM5 - Weight percent of the sample in the -5 phi fraction (nominal diameter of particles greater than or equal to 32 millimeters); very coarse pebbles to boulders



Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: https://pubsdata.usgs.gov/pubs/of/2010/1005/html/seds.html
Page Contact Information: Contact USGS
Page Last Modified: Wednesday, 07-Dec-2016 22:35:46 EST