Finally, one often confusing aspect of reading the referenced reports 

 is the wide variety of names and symbols used for a few concepts and terms. 

 James (1975) discusses this subject and tries to overcome the problem by 

 arranging symbols and terminology in a table showing both previous usage 

 and his usage in the report (Table 1 in James, 1975). This study follows 

 James' guidelines whenever possible, and points out and documents those 

 situations not included in his tabulation. The following listing provides 

 a general perspective for reading the present study: (a) the phi notation 

 (<J>) is used to express sedimentary particle size; (b) the mean and sorting 

 parameters used to describe particle gsd are the phi mean and phi sorting, 

 regardless of the notation used; (c) subscripts, b and n, refer to char- 

 acteristics of borrow site and native beach sediments, respectively; (d) 

 fill factors are identified by a capital R subscripted by a letter that 

 identifies the source of the particular factor; and (e) Greek letters 

 identify characteristics of a "population" which are approximated, using 

 "estimators" denoted by alphabetic symbols; e.g., the population mean, y, 

 is estimated by the sample mean, M; the sample sorting s, estimates 

 the populatio'n sorting, a. 



II. DESCRIPTION OF SEDIMENTS 



1. Classification . 



Natural sediments are generally classified as sand, silt, etc., which 

 indicate the dominant component of the particular sediment, and also imply 

 an actual particle-size range as defined by one of several size classifica- 

 tion schemes. The size schemes most commonly used by coastal engineers are 

 the Unified Soils Classification and the Wentworth Classification (Table 

 1). These two classifications assign similar, but different size ranges 

 (in millimeters) to each sediment category. For example, the total range 

 of sand sizes is 0.074 to 4.76 millimeters for the Unified Soils scheme as 

 opposed to 0.062 to 2 millimeters for the Wentworth. Because of these 

 differences, communication problems can be encountered when it is not clear 

 which classification is being used. The most useful size classification 

 for this study is a logarithmic transformation (phi) of the Wentworth 

 scale. 



The Wentworth scale is essentially a geometric scale to the power of 

 2 with individual size classes defined as "twice as large or half as large" 

 as some other class (Table 1). For example, sand ranges from 2 (2 1 ) to 

 0.062 millimeter (1/16 or 2" 1 *), boulder sizes start at 256 millimeters 

 (2 8 ), and clay is finer than 0.0039 millimeter (2 -8 ). Natural beach sedi- 

 ments are generally composed of materials ranging downward from gravel 

 (2 millimeters) to the silt sizes. 



A common way of comparing different beach sands is to look at plots 

 of the cumulative proportion (usually weight percent) of each sample 

 coarser than a series of size classes. These plots tend to be fairly 

 straight and steep in the less than 1-millimeter size classes, and then 

 tend to "tail out" toward the coarser sizes (Fig. l,a; Table 2). A group 

 of plots for several beach sand samples might look similar even though there 

 are important textural differences among the samples. This apparent simi- 

 larity exists because these textural differences occur in the finer sizes 



