Table 4-2. Density of Littoral Materials 



^From Terzaghi and Peck, 1967. 



In tropical climates, calcium carbonate, especially shell material, 

 is often the dominant material in beach sand. In temperate climates, 

 quartz and feldspar grains are the most abundant, commonly accounting for 

 about 90 percent of beach sand. (Krumbein and Sloss, 1963, p. 134.) 



Because of its resistance to physical and chemical changes, and its 

 common occurrence in terrestrial rocks, quartz is the most common mineral 

 found in littoral materials. The relative abundance of non-quartz mate- 

 rials is a function of the relative importance of the sources supplying 

 the littoral zone and the materials available to those sources. The small 

 amount of heavy minerals (specific gravity greater than 2.87) usually 

 found in sand samples may indicate the source area of the material 

 (McMaster, 1954; Giles and Pilkey, 1965; Judge, 1970), and thus they 

 may be used as natural tracers. Such heavy minerals may form black or 

 reddish concentrations at the base of dune scarps, along the berm, and 

 around inlets. Occasionally heavy minerals occur in concentrations great 

 enough to justify mining them as a metal ore. (Everts, 1971; Martens, 1928.) 

 Table 4-3 from Pettijohn (1957, p. 117) lists the 26 most common minerals 

 found in beach sands. 



Sand is by far the most important littoral material in coastal engi- 

 neering design. However, in some localities, such as New England, Oregon, 

 Washington, and countries bordering on the North Sea, gravel and shingle 

 are locally important. Gravel-sized particles are often rock fragments, 

 that is, a mixture of different minerals, whereas sand-sized particles 

 usually consist of single mineral grains. 



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