APPENDIX B 



RESULTS OF GRAIN-SIZE ANALYSIS 



This appendix provides a list of mean grain size and sorting for samples 

 analyzed by sieving and settling-tube techniques. Sieve data were obtained by 

 sieving samples at 0. 5-phi intervals for periods of 20 to 30 minutes. Raw 

 weights were used to calculate mean grain size and sorting by use of the 

 method of moments. 



Settling-tube data were obtained by analyzing samples on the CERC Rapid 

 Sediment Analyzer (RSA). The RSA method records at the top and bottom of a 1- 

 meter-long plastic tube as grains settle through the water column through use 

 of two pressure transducers. Pressure data are digitized and converted to 

 equivalent size data of spherical quartz grains, and mean grain size and 

 sorting are computed by the method of moments. Through comparison of the 

 results of samples analyzed by both the RSA and sieving techniques, empirical 

 relationships were developed for converting data obtained on the RSA to its 

 sieve equivalent. These expressions, given below, were used to convert RSA 

 means and sorting values to their sieve equivalents. 



Mean: *Sieve = °' 1876 + 1-0735 $ RSA 



Sorting: S. = -0.146 + 1.453 S. 



"frsieve *RSA 



Conversion between phi units and millimeters for grain diameters is pos- 

 sible using the Wentworth grain-size scale (Table 4). The techniques are 

 discussed in the Shore Protection Manual (U.S. Army, Corps of Engineers, 

 Coastal Engineering Research Center, 1977) and Hobson (1979). 



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