broad classes differentiated from one another primarily by texture and secondarily by 

 composition. Each type incorporates a broad range of sediments with regard to color, 

 stratigraphic position, and immediate origin. 

 b. Type A Sediment. 



(1) Physical Characteristics. The most common type of sediment in Cape Canaveral 

 grid is a fine to coarse, moderately well-sorted sand called Type A sediment. (See Figure 

 11.) This sand is composed of nearly equal parts of terrigenous and biogenic material; the 

 biogenic component generally decreases witii reduction in mean grain size. 



Mean grain size of Type A ranges from the middle of fine sand (0.177 mm or 2.50 phi) 

 to the upper limits of coarse sand (0.841 mm or 0."25 phi); most samples have a mean size of 

 between 0.125 mm (2.0 phi) and 0.707 mm (0.5 phi). Sorting of Type A sediments is good 

 relative to other marine sediments in this region; standard deviations range from 0.841 mm 

 (0.25 phi) to 0.420 mm (1.25 phi), very well-sorted to moderately well-sorted in terms 

 defined by Friedman (1962). Standard deviation and mean grain size are plotted in Figure 

 12 for 131 representative Type A sediment samples. Variation in mean size and sorting in 

 the figure reflects shell size and abundance rather than contribution of fines. 



Type A sediments are predominantly hght gray (10 yr. 7/1), dark gray (10 yr. 4/1) light 

 brownisii-gray and variegated. Variation in color is caused by relative abundance and color 

 of carbonate grains, degree of iron staining of detrital grains, and relative abundance of 

 fines. Surficial iron oxide grain coating is common in many Type A sediments, particularly 

 in the upper 2 core-feet, and has a distinct red-brownish gray (5 yr. 7/2) color to the 

 sediment. Compared to other areas of the southeastern U.S. Continental Shelf, Florida shelf 

 samples consistently contain low abundance (H 4 percent) of iron-stained quartz grains. 

 (Judd, Smith, and Pilkey, 1969.) High abundances (K 30 percent) of iron-coated grains in 

 the study area suggest that either localized concentrations occur in the area or that coating 

 of the grains occurred after collection of the samples, perhaps during storage of the cores. 



(2) Composition. Type A sediments contain an admixture of nearly equal parts of 

 terrigenous grains and biogenic carbonate grains. While similar in physical characteristics. 

 Cape Canaveral Type A sediment is more quartzose than sands off Fort Pierce which are 

 about 35 percent. (Meisburger and Duane, 1971.) Most samples contain between 40 percent 

 and 60 percent calcium carbonate by weight; however, fine sands associated with 

 shore-connected shoals contain as little as 15 percent carbonate, and in other areas of the 

 grid, local concentrations of shell yield calcium carbonate values as high as 85 percent. 



Terrigenous fraction is predominantly quartz witii small amounts of feldspar, heavy 

 minerals and phosphorite. Mica is absent from Type A sediments, perhaps as a function of 

 the combined factors of source distance and grain durability. Quartz grains mostly show 

 signs of recent abrasion and polishing, particularly in the shoal areas. Grains collected at 

 depth of 12 feet subbottom from Hetzel Shoal, Ohio Shoal and The Bull have a high degree 

 of polish and luster, similar to grains from siioal surfaces and the adjacent beaches. Between 

 and seaward of shoals, grains are often covered with a superficial iron oxide and algal 

 coating. Roundness of Type A quartz grains ranges between subrounded and angular; a small 

 percentage of very angular to well-rounded quartz grains is present, however, probably 

 indicating both recent breakage and diagenetic alteration. 



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