U.S. Department of the Interior  -   U.S. Geological Survey

U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 00-358

CHAPTER 2: USGS EAST-COAST SEDIMENT TEXTURE DATABASE

Hastings, M.E., Poppe, L.J., and Hathaway, J.C
Coastal and Marine Geology Program, USGS, Woods Hole, MA 02543

INTRODUCTION

 

            Many scientific questions and policy issues related to sediments require data of historical, regional and interdisciplinary scope.  Existent data are often geographically clustered and its references are widely dispersed and not always accessible.  Acquisition of new data is expensive and may duplicate previous efforts if a full interpretation of existent data has not occurred. Consequently, the body of existing data need to be utilized to its maximum so that it can serve as a foundation, baseline, and starting point for further work. An accessible, documented, and simple-to-use compilation of existing data on sediment properties is essential for environmental managers, policy-makers, scientific researchers, and interested members of the public. To this end, we have compiled, edited, and integrated the available data on sediment texture and bottom descriptions produced at the Woods Hole Field Center of the Coastal and Marine Geology Program (CMGP) of the U.S. Geological Survey (USGS) in order to produce a regional database which will be available to a wide variety of current and potential users.  The sediment database presented herein is also being merged with data from other federal agencies in a Microsoft  Access relational database, which is currently being developed as part of the USGS CMGP Aggregates Project. Hopefully both databases will grow and evolve, remaining applicable to questions and models developed in the future.

            This sediment database contains data on collection, location, description, and texture of samples taken by numerous marine sampling programs.  Most of the samples are from the Atlantic Continental Margin of the United States, but some are from as diverse locations as Lake Baikal, Russia, the Hawaiian Islands region, Puerto Rico, the Gulf of Mexico, and Lake Michigan. The database presently contains data for over 19,000 samples, which includes texture data for approximately 3800 samples taken or analyzed by the Atlantic Continental Margin Program, a joint U.S. Geological Survey/Woods Hole Oceanographic Institution project conducted from 1962 to 1970 (Emery and Schlee, 1963). The data from this program were originally reported by Hathaway, J.C., 1971. Texture data for approximately 14,500 samples analyzed by the Sediment Laboratory of the USGS CMGP, Woods Hole MA. after 1980 make up the rest of the database. Considerable data from the period 1970 to 1980 have yet to be digitized and included.  Although most records contain complete grain size analyses, some are simple bottom descriptions from rocky and bouldery locations where samples were not taken. Most of the samples were collected with some type of grab sampler; however, a few were obtained by coring.

            Individuals should be careful when assuming geodetic controls for the textural data because different systems, datums, and navigational equipment were used to locate the sample sites.  Geodetic systems and datums define the assumed shape and size of the earth and the origin and orientation of the coordinate systems used to map its surface.  Referencing latitude and longitude coordinates to the wrong system or datum may result in significant position errors.  Most of the sampling conducted prior to 1971 was navigated with Loran-A and is based partly on the Clark 1866 and partly on World Geodetic System 1964 (WGS-84) reference ellipsoids, and most of the sampling conducted between 1972-1988 was navigated with Loran-C and is based on the World Geodetic System 1972 (WGS-72). The Loran shore stations for the North American sample sites were surveyed on the 1927 North American Datum (NAD 27).  Finally, most of the sampling conducted after 1988 was navigated with the Global Positioning System (GPS) and is based on the World Geodetic System 1984 (WGS-84).  Conversion programs that allow interested scientists to adjust between the different reference ellipsoids and cartographic datums (e.g. NADCON) are readily available on the World Wide Web.  Of perhaps equal or greater concern is the horizontal error associated with the above mentioned navigational equipment.  These errors vary spatially and average approximately 185-460 m (absolute accuracy), <100 m, and <10 m for Loran-C, GPS, and differential GPS, respectively (D. Olmsted, Woods Hole Oceanographic Institution, oral communication).  Generally, Loran-A had an average expected accuracy of 1 percent of the distance between the navigator and the stations (U.S. Coast Guard, 1949).

 

DATABASE PLATFORM AND FORMATS

 

            Our objective was to gather all of the available data on grain size for the bottom sediments produced by the Woods Hole Field Center of the U.S. Geological Survey into a scientifically-edited database that will allow scientists, policy makers, and others to manipulate, query, and display the original data themselves in order to address their own specific applications. Requirements for the database formats are that they be comprehensive and simple for both entering and extracting data.

            The basic structure of the database is a matrix where records are rows representing individual samples and the columns contain information on sample identification, navigation, classifications, analyzed parameters, and comments. This is a "flat-file" format, which means that it is not "normalized".  While this is considered inefficient from the point of view of database management, it is the simplest way of presenting the basic data.  This structure was chosen to avoid ambiguity, and to make the process of locating fields, entering data, and validating it as simple yet comprehensive as possible.  Since we know neither the software capabilities of the user nor the probable uses that may be made of the data, we have made no attempt to split the files to reduce blank fields or to remove redundancies. The same data may be presented in more than one form, e.g.: phi class frequencies and cumulative frequencies. Even though each form can be derived from the other, presenting both eliminates the need for the user to program formulas to calculate one from the other.  Although this may violate the principal of having a single entry for any given data item, it greatly simplifies the use of the file.  If the user wishes to make the data base more efficient through "normalization", we feel that it is better that this be done by the user to fit both the applications available to the user and the database structural logic that is familiar to the user.  The price paid for the "flat file" approach is additional storage space, rather wide records, and the possibility that corrections made here at the source may fail to be carried through to all forms of the data affected.  We have made every effort to insure against this last possibility.

            The database presented here contains 98 fields (see the Data Dictionary below). The specific fields and parameters have been chosen based on the data produced by the Sedimentation Laboratory of the Coastal and Marine Geology Program of the U.S. Geological Survey in Woods Hole, MA, and the format of information typically found in the literature. Because the data have come from numerous sources, there are differing amounts and types of information. Most of the samples or sets of samples do not have data in all of the given fields; however, additional fields, qualifiers, and data can be added in virtually unlimited fashion to accommodate specific needs.

            Data that comes from the Woods Hole Sediment Laboratory are exported as standard pre-database files (see Figure 26, Chapter 1, Poppe and others, this CD-ROM).  Several steps are taken to massage these data.  First, area and sampling device codes are assigned full definitions, phi classes and phi ranges are calculated from the cumulative phi values, and the analyst’s name is added.  The classification of “Gravel >10%” is changed to either or “Gravelly sediment” or “Gravel” based on the actual gravel content (Gravel >10% but <=50% or Gravel >50%, respectively).  The USGS Administrative Cruise Summary is consulted in an attempt to add the approximate (month and year) sample collection dates, and the data fields are rearranged to conform to the Data Dictionary (see below).

            The database itself is provided in three formats: two popular software formats and one delimited ASCII text format. All were created in Microsoft Excel 2000. In the delimited ASCII text file, each field or column of data is separated from the next by tabs and can be downloaded into many types of software. The formatted files will open in the appropriate software if the user has the applications installed and their web browser properly configured.

 

* ECST0500.xls                       Microsoft Excel 97-2000 & 5.0/95 (26.5 Mb)

* ECST0500.dbf                      Dbase IV (20.8 Mb)

* ECST0500.txt                       Tab-delimited text (7 Mb)

 

The tab-delimited file contains data as well as headings for the tables of data in uncompressed ASCII format. This file is supplied for users who do not have a DOS or Windows compatible computer, or for users who wish to import the data into unaccommodated applications that can accept ASCII character information.

            The sediment database presented herein can also be imported into Microsoft Access by using the file supplied in Excel format (ECST0500.xls).  To do this, first create a new database in Access by selecting File/New Database and give the database a name.  Create a new table in this database by selecting the Tables tab and choosing New/Import Table.  Navigate to the folder on the CD-ROM where the Excel version of the database is located and in the Files of Type box in Access, choose Microsoft Excel (.xls).  Select the file and choose Import.  This will open the Import Spreadsheet Wizard dialog box. Click on the box that says First Row Contains Column Headings, and then choose Next.  If there are invalid names, Access will assign a field name (e.g. Field 12), which can later be changed.  Valid field names cannot include a period, an exclamation point, an accent grave, or brackets.  To create a new table in this database, select In a New Table and then choose Next.  This dialog box gives options for changing field names, data types and indexing.  The options for each column can be changed by selecting the column in the bottom half of the box.  Change any options you wish and then choose Next.  Specify the primary key in the following box or allow Access to do it for you, and choose Next. In the last dialog box, give the table a name and choose Finish.  Access will then import the table.  If Access encounters any errors or bad records, it will display an error message and then create a table called "Yourfilename$_ImportErrors."  The table will list the error type, the field where the error was encountered, and the row number.

 

VISUALIZATION OF THE TEXTURAL DATABASE

 

            Those samples for which full grain-size data are available were also assigned classifications based on definitions found in Shepard (1954).  In displaying the lithologic descriptors, the general ranking principle of the main constituents (e.g. gravel, sand) and modifying constituents (e.g. sandy, silty) follows in order of decreasing coarseness. The color display follows this pattern:

 

Red       - sediment whose main phase is gravel (>=50%); rocky bottom

Orange  - sediment with significant amounts of gravel (>10%, but <50%)

Yellow  - sediment whose main phase is sand without significant gravel or mud

Light Green  - sediment whose main phase is sand (>50%) with significant silt or clay

Dark Green - sediment with significant sand, silt, and clay

Blue      - sediments whose main phase is silt (Usually >50%)

Purple   - sediments whose main phase is clay (Usually >50%)

Black    - bedrock (based on visual observation)

 

Available overviews of the sediment classes from the data in this archive include:

 

            * The Atlantic Continental Margin

            * Georges Bank/Gulf of Maine

            * Mid-Atlantic/NY Bight

            * North and South Carolina (Carolina Trough)

            * Georgia and Florida (Blake Plateau Basin)

            * Gulf of Mexico

            * Puerto Rico

 

Also available is an overview showing those samples which have a lithologic description but incomplete size data or no rigorous classification.

 

            * Lithology only

 

 

 

DATA DICTIONARY

 

            An integral part of any functioning database is the dictionary that explains the structure and content of the database.  The dictionary contains an index and definitions of the parameters measured and lists the fields which record and qualify those parameters. Extracting data from the database is facilitated by reference to this document because it provides a means to keep track of abbreviations and the sediment fields names. A copy of this data dictionary (datadict.xls) may also be downloaded in Microsoft Excel 5.0/95 format.

 

Short Field Name  |  Full-Length Field Name  |  Field Description

 

GROUP  |  Group  |  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 = samples analyzed by the USGS Branch of Atlantic Marine Geology Sediment Laboratory

 

USGS DB_ID  |  USGS unique sample identifier  |  Unique identification number (consisting of 2 characters and 3 numerics) generated in the sedimentation laboratory of the USGS's Woods Hole Field Center for the Atlantic Margin Texture Database

 

FIELD_ID  |  Field identifier  |  Sample name or number as assigned in the field

 

PROJ_NAME  |  Project name  |  Project under which samples were taken or data generated; sometimes indicates more specific area

 

CRUISE_ID  |  Cruise ID  |  Name or number of cruise on which sample collected

 

CONTACT  |  Principal contact  |  Name of Principal Investigator (usually first initial and last name)

 

AREA  |  Area  |  General geographic area (general enough to easily locate on a state map )

 

LATITUDE  |  Latitude  |  Latitude in decimal-degrees (south latitudes are depicted by  negative values)

 

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

 

ORIG_PREC  |  Original Precision  |  Precision of location measurement (e.g., DM for degrees and minutes, DMS.x for degrees, minutes, and seconds to the tenth decimal position)

 

DEPTH_M  |  Depth or sounding in meters  |  Measured depth of water overlying sediment at sample time, not corrected for tides, in meters

 

SOUND.METHOD  |  Sounding method  |  Method used to ascertain depth

 

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

 

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

 

DEVICE  |  Sampling device  |  Device used to collect the sample

 

MONTH_COLL  |  Month collected  |  Calendar month sample collected

 

DAY_COLL  |  Day collected  |  Calendar day sample collected

 

YEAR_COLL  |  Year collected  |  Calendar year sample collected

 

LITHOLOGY  |  Lithology  |  General lithologic description of sample

 

COMMENTS  |  Comments  |  Comments on sample collection or lithology

 

MNTH_ANAL  |  Month analyzed  |  Calendar month sample analyzed

 

DAY_ANAL  |  Day analyzed  |  Calendar day sample analyzed

 

YEAR_ANAL  |  Year analyzed  |  Calendar year sample analyzed

 

WEIGHT  |  Weight  |  Weight of wet sample in grams

 

GRAVEL_PCT  |  %Gravel  |  Gravel content in percent dry weight of the sample (particles with nominal diameters greater than 2 mm; -1   and larger)

 

SAND_PCT  |  %Sand  |  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  through 4 )

 

SILT_PCT  |  %Silt  |  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  through 8 , inclusive)

 

CLAY_PCT  |  %Clay  |  Clay content in percent dry weight of the sample (particles with nominal diameters less than 0.004 mm; 9  and smaller)

 

SED_CLASS  |  Classification  |  Sediment description based on a rigorous definition

 

CLASS_CODE  |  Classification code  |  Code number assigned based on sample classification; for plotting purposes only (see Visualization of the Textural Database)

 

MEDIAN  |  Median  |  Middle point in the grain size distribution in phi units

 

MEAN  |  Mean  |  Average value in the grain size distribution in phi units

 

STDEV_SORT  |  Standard deviation (sorting)  |  Standard deviation (root mean square of the deviations) of the grain size distribution in phi units

 

SKEWNESS  |  Skewness  |  Skewness (deviation from symmetrical form) of the grain size distribution in phi units

 

KURTOSIS  |  Kurtosis  |  Kurtosis (degree of curvature near the mode) of the grain size distribution in phi units

 

MODE_1_CLA  |  Mode 1 class  |  First mode (particle size that occurs the most number of times) in phi units

 

MODE_1_STR  |  Mode 1 strength  |  Modal strength of the first mode in percent

 

MODE_2_CLA  |  Mode 2 class  |  Second mode in phi units

 

MODE_2_STR  |  Mode 2 strength  |  Modal strength of the second mode in percent

 

MODE_3_CLA  |  Mode 3 class  |  Third mode in phi units

 

MODE_3_STR  |  Mode 3 strength  |  Modal strength of the third mode in percent

 

N_MODES  |  Number of modes  |  Number of modes

 

PHI_STEP  |  Phi step  |  Phi interval used in analysis (e.g. full phi, half phi)

 

FROM_PHI  |  From Phi  |  Largest particle size measured, in phi units

 

TO_PHI  |  To Phi  |  Smallest particle size measured, in phi units

 

PHI-11  |  -11 Phi  |  Weight percent of the sample in the -11  fraction (nominal diameter of particles greater than or equal to 2048 mm)

 

PHI-10  |  -10 Phi  |  Weight percent of the sample in the -10  fraction (nominal diameter of particles greater than or equal to 1024 mm, but less than 2048 mm)

 

PHI-9  |  -9 Phi  |  Weight percent of the sample in the -9  fraction (nominal diameter of particles greater than or equal to 512 mm, but less than 1024 mm)

 

PHI-8  |  -8 Phi  |  Weight percent of the sample in the -8  fraction (nominal diameter of particles greater than or equal to 256 mm, but less than 512 mm); boulders

 

PHI-7  |  -7 Phi  |  Weight percent of the sample in the -7  fraction (nominal diameter of particles greater than or equal to 128 mm, but less than 256 mm); large cobbles

 

PHI-6  |  -6 Phi  |  Weight percent of the sample in the -6  fraction (nominal diameter of particles greater than or equal to 64 mm, but less than 128 mm); small cobbles

 

PHI-5  |  -5 Phi  |  Weight percent of the sample in the -5  fraction (nominal diameter of particles greater than or equal to 32 mm, but less than 64 mm); very coarse pebbles

 

PHI-4  |  -4 Phi  |  Weight percent of the sample in the -4 fraction (nominal diameter of particles greater than or equal to 16 mm, but less than 32 mm); coarse pebbles

 

PHI-3  |  -3 Phi  |  Weight percent of the sample in the -3  fraction (nominal diameter of particles greater than or equal to 8 mm, but less than 16 mm); medium pebbles

 

PHI-2  |  -2 Phi  |  Weight percent of the sample in the -2  fraction (nominal diameter of particles greater than or equal to 4 mm, but less than 8 mm); fine pebbles

 

PHI-1  |  -1 Phi  |  Weight percent of the sample in the -1  fraction (nominal diameter of particles greater than or equal to 2 mm, but less than 4 mm); very fine pebbles (granules)

 

PHI_0  |  0 Phi  |  Weight percent of the sample in the 0 fraction (nominal diameters of particles greater than or equal to 1 mm, but less than 2 mm); very coarse sand

 

PHI_1  |  1 Phi  |  Weight percent of the sample in the 1  fraction (nominal diameter of particles greater than or equal to 0.5 mm, but less than 1 mm); coarse sand

 

PHI_2  |  2 Phi  |  Weight percent of the sample in the 2  fraction (nominal diameter of particles greater than or equal to 0.25 mm, but less than 0.5 mm); medium sand

 

PHI_3  |  3 Phi  |  Weight percent of the sample in the 3  fraction (nominal diameter of particles greater than or equal to 0.125  mm, but less than 0.25 mm); fine sand

 

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

 

PHI_5  |  5 Phi  |  Weight percent of the sample in the 5  fraction (nominal diameter of particles greater than or equal to 0.031 mm, but less than 0.0625 mm); coarse silt

 

PHI_6  |  6 Phi  |  Weight percent of the sample in the 6  fraction (nominal diameter of particles greater than or equal to 0.016 mm, but less than 0.031 mm); medium silt

 

PHI_7  |  7 Phi  |  Weight percent of the sample in the 7  fraction (nominal diameter of particles greater than or equal to 0.008 mm, but less than 0.016 mm); fine silt

 

PHI_8  |  8 Phi  |  Weight percent of the sample in the 8 fraction (nominal diameter of particles greater than or equal to 0.004 mm, but less than 0.008 mm); very fine silt

 

PHI_9  |  9 Phi  |  Weight percent of the sample in the 9  fraction (nominal diameter of particles greater than or equal to  0.002 mm, but less than 0.004 mm); coarse clay

 

PHI_10  |  10 Phi  |  Weight percent of the sample in the 10  fraction (nominal diameter of particles greater than or equal to 0.001 mm, but less than 0.002 mm); medium clay

 

PHI_11  |  11 Phi  |  Weight percent of the sample in the 11  fraction (nominal diameter of particles greater than or equal to 0.5 m, but less than 0.001 mm); fine clay

 

PHI_12  |  12 Phi  |  Weight percent of the sample in the 12  fraction (nominal diameter of particles greater than or equal to 0.25 m, but less than 0.5 m); very fine clay

 

PHI_13  |  13 Phi  |  Weight percent of the sample in the 13  fraction (nominal diameter of particles greater than or equal to 0.125  m, but less than 0.25 m)

 

PHI_14  |  14 Phi  |  Weight percent of the sample in the 14  fraction (nominal diameters of particles greater than or equal to .125 m, but less than 0.0625 m)

 

PHI_15  |  15 Phi  |  Weight percent of the sample in the 15  fraction (nominal diameter of particles greater than or equal to 0.0625 m, but less than 0.031 m)

 

PHI_16  |  16 Phi  |  Weight percent of the sample in the 16  fraction (nominal diameter of particles greater than or equal to 0.031 m, but less than 0.0125 m)

 

PHI_17  |  17 Phi  |  Weight percent of the sample in the 17  fraction (nominal diameter of particles greater than or equal to 0.0125 m, but less than 0.00625 m)

 

PHI_18  |  18 Phi  |  Weight percent of the sample in the 18 fraction (nominal diameter of particles greater than or equal to 0.00625 m, but less than 0.0031 m)

 

PHI_19  |  19 Phi  |  Weight percent of the sample in the 19  fraction (nominal diameter of particles greater than or equal to  0.0031 m, but less than 0.00125 m)

 

PHI_20  |  20 Phi  |  Weight percent of the sample in the 20  fraction (nominal diameter of particles greater than or equal to 0.00125 m, but less than 0.625 m)

 

PHI_21  |  21 Phi  |  Weight percent of the sample in the 21 fraction (nominal diameter of particles greater than or equal to 0.625 nm, but less than 0.31 m)

 

PHI_22  |  22 Phi  |  Weight percent of the sample in the 22 fraction (nominal diameter of particles greater than or equal to 0.31 m)

 

CFP11  |  Cfp11  |  Cumulative frequency percent of the 11  fraction and coarser (less than 0.001 mm)

 

CFP10  |  Cfp10  |  Cumulative frequency percent of the 10  fraction  and coarser (less than 0.002 mm)

 

CFP09  |  Cfp09  |  Cumulative frequency percent of the 9  fraction and coarser (less than  0.004 mm)

 

CFP08  |  Cfp08  |  Cumulative frequency percent of the 8  fraction and coarser (less than  0.008 mm)

 

CFP07  |  Cfp07  |  Cumulative frequency percent of the 7  fraction and coarser (less than 0.0016 mm)

 

CFP06  |  Cp06  |  Cumulative frequency percent of the 6  fraction and coarser (less than 0.031 mm)

 

CFP05  |  Cfp05  |  Cumulative frequency percent of the 5  fraction and coarser (less than 0.062 mm)

 

CFP04  |  Cfp04  |  Cumulative frequency percent  of the 4  fraction and coarser (less than 0.125 mm)

 

CFP03  |  Cfp03  |  Cumulative frequency percent  of the 3  fraction and coarser (less than 0.250 mm)

 

CFP02  |  Cfp02  |  Cumulative frequency percent  of the 2  fraction and coarser (less than 0.5 mm)

 

CFP01  |  Cfp01  |  Cumulative frequency percent  of the 1  fraction and coarser (less than 0.1 mm)

 

CFP00  |  Cfp00  |  Cumulative frequency percent  of the 0  fraction and coarser (less than 2 mm)

 

CFPM1  |  Cfpm1  |  Cumulative frequency percent  of the -1  fraction and coarser (less than 4 mm)

 

CFPM2  |  Cfpm2  |  Cumulative frequency percent  of the -2  fraction and coarser (less than 8 mm)

 

CFPM3  |  Cfpm3  |  Cumulative frequency percent of the -3  fraction and coarser (less than 16 mm)

 

CFPM4  |  Cfpm4  |  Cumulative frequency percent of the -4  fraction and coarser (less than 32 mm)

 

CFPM5  |  Cfpm5  |  Cumulative frequency percent of the -5  fraction and coarser (distribution is usually less than 64 mm)

 

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

 

ANAL_COMM  |  Comments on analyses  |  Any further information about sediment analysis for all or specific parameters in this table

 

ACKNOWLEDGMENTS

 

            This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards (or with the North American Stratigraphic Code). Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.  Image on the title page is clipart from Corel XARA (v. 1.5).  We thank J. Schlee, J. Frothingham, C. Hayes, M. Ferrebee, D. Eskinasy, S. Wood, C. Parmenter, B. Brewster, H. Maiers, G. Kineke, S. Mateus, A. Brown, M. Moffett, C. Wright, R. Siplac, A. Harmon, B. Taylor, B. Kennedy, S. Parolski, A. Robinson, D. Walsh, and E. Loftfield, the sediment lab analysts who generated the data presented in this report, and J. Reid, who helped refine the instructions to import these data into Access.

 

 

REFERENCES CITED

 

Emery, K.O., and Schlee, J.S., 1963, The Atlantic Continental Shelf and Slope, a program for study: U.S. Geological Survey Circular 481, 11 p.

 

Hathaway, J.C., 1971, Data File - Continental Margin Program: Woods Hole Oceanographic Institution Technical Report 71-15, 492 p.

 

Shepard, F.P., 1954, Nomenclature based on sand-silt-clay ratios: Journal of Sedimentary Petrology, v. 24, p. 151-158.

 

U.S. Coast Guard, 1949, Electronic navigational aids: CG157, 73 p.

 

DISCLAIMER

 

            The database presented here has been approved for release and publication by the Director of the USGS.  Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review.   Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.

 

 

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