The complete grain-size dataset including all GRADISTAT parameters, results of individual sample runs, and standard deviations for all sample averages are included in the unedited output files (
https://pubs.usgs.gov/ds/0999/downloads/14CTB_SandAugers_RunStats.zip). Sample runs in the output files for which the mean Folk and Ward grain size varied from the set average by more than 1.5 standard deviations are highlighted in yellow and were not included in final averaged results.
This grain-size dataset includes results for 400 samples from 46 sand augers collected from Assateague Island, Maryland in March/April and October 2014 (USGS FAN 2014-301-FA, 2014-322-FA).
Process_Step:
Process_Description:
USGS scientists collected sediment samples from sand augers (sample type W) from three active overwash zones (transects 1, 3, and 4) and one control transect (transect 2) on Assateague Island during two surveys—one in the spring, March 26 to April 4, 2014, and one in the fall, October 21–30, 2014 (USGS FAN 2014-301-FA and 2014-322-FA, respectively). During the spring survey, at total of 19 cores were collected from 17 sites, including 8 cores from 7 back-barrier marsh sites. During the fall survey, all of the spring sand auger sites were re-cored, and additional cores were collected from overwash deposits at transects 1 and 4; in October, a total of 81 core sections were collected from 69 sites.
Cores were collected using an AMS sand/loose sediment soil probe, which can accommodate a 2.54-centimeter(cm) (1-inch) diameter by approximately 60-cm (2-feet) plastic sleeve. In addition to cores collected from the ground surface, during the October survey a second core was collected at some sites from a trench dug to just above the groundwater table. After extraction, each core was capped, sealed, and labeled with transect location, core number, and orientation. The cores were transported to the USGS SPCMSC for processing and analysis.
Process_Date: 2014
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Julie C. Bernier
Contact_Position: Geologist
Contact_Address:
Address_Type: Mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727-502-8000
Contact_Electronic_Mail_Address: jbernier@usgs.gov
Process_Step:
Process_Description:
At the SPCMSC sediment laboratory, the cores were split lengthwise, x-rayed, photographed, described macroscopically using standard sediment-logging methods, and subsampled at 1.5- to 2-cm intervals for grain-size analysis. Sample frequencies varied between cores depending on observed sedimentologic changes. Some cores were sampled at high frequencies to characterize the washover deposits, whereas in other cores the sampling strategy was more targeted.
Process_Date: 2015
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Julie C. Bernier
Contact_Position: Geologist
Contact_Address:
Address_Type: Mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727-502-8000
Contact_Electronic_Mail_Address: jbernier@usgs.gov
Process_Step:
Process_Description:
Grain-size analyses were performed using a Coulter LS 13 320 particle-size analyzer, which uses laser diffraction to measure the size distribution of sediments ranging from 0.4 microns (µm) to 2 millimeters (mm) (clay to very coarse-grained sand). A total of 400 samples (including 39 replicates) from 46 core sections were analyzed. Samples consisted of a 1.5- to 2-cm section of the core based on the minimum amount of material needed for analysis.
In order to prevent shell fragments from damaging the LS 13 320, particles greater than 1 mm in diameter were separated from all samples prior to analysis using a number 18 (1,000 µm, 1 mm) U.S. standard sieve, which meets the American Society for Testing and Materials (ASTM) E11 standard specifications for determining particle size using woven-wire test sieves. Prior to sieving, each down-core sample was dried at 60 degrees Celsius for 24 hours, and the fraction of sediment greater than 1 mm was recorded as a percentage of the bulk sample dry weight. For samples (N = 60) that were visually identified as organic rich, organic material was chemically removed using 30 percent hydrogen peroxide (H2O2). Wet sediment was dissolved in H2O2 overnight. The H2O2 was then evaporated through slow heating on a hot plate, and the sediment was washed and centrifuged twice with deionized water. The samples were stored in the centrifuge tubes with several milliliters of deionized water until instrument analysis. Due to a limited quantity of sediment available, quantitative measurements of organic content were not practical.
Each sample was processed through the LS 13 320 a minimum of six runs. The LS 13 320 measures the particle-size distribution of each sample by passing sediment suspended in solution between two narrow panes of glass in front of a laser. Light is scattered by the particles into characteristic refraction patterns measured by an array of photodetectors as intensity per unit area and recorded as relative volume for 92 size-related channels (bins). The size-classification boundaries for each bin were specified based on the ASTM E11 standard.
Process_Date: 2015
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Julie C. Bernier
Contact_Position: Geologist
Contact_Address:
Address_Type: Mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727-502-8000
Contact_Electronic_Mail_Address: jbernier@usgs.gov
Process_Step:
Process_Description:
The raw grain-size data were run through the free, widely available program GRADISTAT (Blott and Pye, 2001), which calculates the geometric (in metric units) and logarithmic (in phi units, Φ; Krumbein, 1934) mean, sorting, skewness, and kurtosis of each sample using the Folk and Ward (1957) method as well as the cumulative particle-size distribution. GRADISTAT also calculates the fraction of sediment from each sample by size category (for example, clay, coarse silt, fine sand) based on a modified Wentworth (1922) size scale. A macro developed by the USGS was applied to calculate the average and standard deviation of each sample (six runs per sample) and highlight runs that varied from the set average by more than plus or minus (±) 1.5 standard deviations. Excessive deviations from the mean are likely the result of equipment error or extraneous material in the sample and are not considered representative of the sample. Those runs were removed from the results and the sample average was recalculated using the remaining runs. The individual run statistics are available from
https://pubs.usgs.gov/ds/0999/downloads/14CTB_SandAugers_RunStats.zip. The averaged results for all samples, including the number of runs used, the standard deviation of the averaged results, and graphical class-size distributions, are summarized in a series of Excel workbooks with each core on its own tab and are available from
https://pubs.usgs.gov/ds/0999/downloads/14CTB_SandAugers_SumStats.zip.
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Julie C. Bernier
Contact_Position: Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727-502-8000
Contact_Electronic_Mail_Address: jbernier@usgs.gov
Process_Step:
Process_Description:
Keywords section of metadata optimized by adding theme keyword thesauri and associated keywords.
Process_Date: 20180327
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Arnell S. Forde
Contact_Position: Geologist
Contact_Address:
Address_Type: Mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: aforde@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20201013
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
