U.S. Geological Survey East-Coast Sediment Texture Database

Field Description

Number assigned to data based on source:

1. Samples taken before start of the joint USGS/WHOI project
2. USGS/WHOI Atlantic Continental Margin Program stations
3. Sediment entirely or partially analyzed, processed, or visually described by USGS Woods Hole scientists; most samples analyzed in the USGS Woods Hole Sediment Laboratory.

Unique identification number generated in the sedimentation laboratory of the USGS's Woods Hole Coastal and Marine Science Center. For samples analyzed after 1980 this identifier consists of 2 characters and 3 numerics (e.g. AS114). For samples analyzed before 1980, this identifier consists of 4 numerics possibly followed by as many as 2 characters.

Sample name or number as assigned in the field by the Chief Scientist.

Project name or number under which samples were taken or data generated; sometimes project name indicates a more specific area.

Name or number of cruise on which sample collected. Historically cruise identifiers were a combination of ship name, year of cruise and cruise leg. In more recent years, cruise identifier is a sequential serial number assigned to field activities within a specific year.

Name of Principal Investigator or Chief Scientist responsible for data collection (usually first initial and last name)

General geographic area of data collection. Name is general enough to easily locate area on a state map.

Latitude coordinate, in decimal-degrees, of sample location. South latitude recorded as negative values.

Longitude coordinate, in decimal degrees, of sample location. West longitude is recorded as negative values.

Measured depth, in meters, of water overlying sediment at sample time. Depth value is not corrected for tides.

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

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

Device used to collect the sample.

Calendar month during which sample was collected.

Calendar day on which sample was collected.

Calendar year during which sample was collected.

Calendar month during which sample completed analysis.

Calendar day on which sample completed analysis.

Calendar year during which sample completed analysis.

Weight of dry sample in grams.

Gravel content in percentage of dry weight of the sample (particles with nominal diameters greater than 2 mm; -1 phi and larger).

Sand content in percentage of 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).

Silt content in percentage of 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).

Clay content in percentage of dry weight of the sample (particles with nominal diameters less than 0.004 mm; less than 8 phi).

Sediment description based on rigorous definition usually Shepard (1954) as modified by Schlee and Webster (1967), Schlee (1973), and Poppe and others (2005).

For sediments with gravel equal to or greater than 10 percent:

• GRAVEL – gravel equal to or greater than 50 percent
• GRAVELLY SEDIMENT – gravel equal to or greater than 10 percent, but less than 50 percent

For sediments with gravel less than 10 percent:

• SAND – sand equal to or greater than 75 percent
• SILTY SAND - sand less than 75 percent and equal to or greater than 50 percent, silt is greater than clay, and clay less than 20 percent
• CLAYEY SAND - sand less than 75 percent and equal to or greater than 50 percent, clay is greater than silt, and silt less than 20 percent
• SILT - silt equal to or greater than 75 percent
• SANDY SILT – silt less than 75 percent and equal to or greater than 50 percent, sand is greater than clay, and clay less than 20 percent
• CLAYEY SILT - silt less than 75 percent and equal to or greater than 50 percent, clay is greater than sand, and sand less than 20 percent
• CLAY – clay equal to or greater than 75 percent
• SANDY CLAY - clay less than 75 percent and equal to or greater than 50 percent, sand is greater than silt, and silt less than 20 percent
• SILTY CLAY - clay less than 75 percent and equal to or greater than 50 percent, silt is greater than sand, and sand less than 20 percent
• SAND SILT CLAY – all of these components greater than 20 percent

Middle point in the grain size distribution, in phi units.

Average value in the grain size distribution, in phi units.

Standard deviation (root mean square of the deviations) of the grain size distribution, in phi units.

Skewness (deviation from symmetrical form) of the grain size distribution, in phi units.

Kurtosis (degree of curvature near the mode) of the grain size distribution, in phi units.

First mode (particle size that occurs the most number of times), in phi units.

Modal strength of the first mode, in percent.

Second mode, in phi units.

Modal strength of the second mode, in percent.

Third mode, in phi units.

Modal strength of the third mode, in percent.

Number of modes.

Weight percentage of the sample in the -5 phi fraction and coarser (nominal diameter of particles greater than or equal to 32 mm); very coarse pebbles to cobbles

Weight percentage 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.

Weight percentage 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.

Weight percentage 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.

Weight percentage 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).

Weight percentage of the sample in the 0 phi fraction (nominal diameter of particles greater than or equal to 1 mm, but less than 2 mm); very coarse sand.

Weight percentage 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.

Weight percentage 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.

Weight percentage 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.

Weight percentage of the sample in the 4 phi fraction (nominal diameter of particles greater than or equal to 0.0625 mm, but less than 0.125 mm); very fine sand.

Weight percentage 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.

Weight percentage 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.

Weight percentage 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.

Weight percentage 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.

Weight percentage 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.

Weight percentage 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.

Weight percentage of the sample in the 11 phi fraction and finer (nominal diameter of particles less than 0.001 mm); fine clay.

Name (usually first initial and last name) of person who performed the grain size or physical properties analysis.

Any further information about sediment analysis for all or specific parameters in this table.

General lithologic description of sample.

Comments on sample collection or lithology.