Sand-size material is predominantly detrital quartz and accessory heavy minerals. 

 Feldspars rarely comprise more than 1 percent of the terrigenous minerals. Micas are 

 generally absent. Biogenous carbonate grains are a significant part (between 10 and 60 

 percent) of the sands in this region. The grains are primarily mollusks; also present are 

 foraminifera, ostracods, bryozoans and fragments of echinoids and barnacles. Nonskeletal 

 and nonsihcate sand grains are less abundant and include relict ooids, detrital phosphorite 

 grains, and calcarenite fragments. 



Clays and silts are abundant in this segment of the study area. These muds are composed 

 of terrigenous clay minerals, detrital quartz silt, and skeletal carbonate silt in various 

 proportions. Calcareous silt constitutes the majority of the fines, mostly in the southern half 

 of the region. 



Lateral and vertical distribution of major sediment types is depicted in Figure 16. In 

 general, individual hthologies are characterized by homogeneity and distinct similarities; 

 individual types are correlated through as many as 12 cores and over a distance of 20 

 nautical miles. Shelf sediments to a subbottom depth of 12 feet in Canaveral Bight are 

 uniform in lithology and extensive in areal distribution (Cores 97, 100, 101, 110, and 115, 

 Fig. 16). The sediments are admixtures of modern terrigenous clays, detrital carbonate and 

 quartz silt, and very fine quartz sands. Gravel-size shells and shell fragments are common in 

 localized concentrations. The shells are light gray and white, and shell fragments are 

 typically very angular, indicating lack of significant transport and abrasion subsequent to 

 fracture. Principal contributor is Anadara transversa, but other mollusks are present. Fine 

 calcareous particles in Canaveral Bight are skeletal fragments and tests. A well-sorted 

 medium-grained quartzose sand is present in three of the cores at subbottom depths of 3, 5, 

 and 6 feet. Occasional whole shells of Mulinia laterata and Crepidula fornicata are present, 

 but most carbonate grains are sand size, blackened mollusk fragments with rounded and 

 polished surfaces, benthonic foraminifera, ooids (1 to 4 percent), and lithoclasts. 



Sands enriched in fibrous organic matter and sandy peats are in Canaveral Bight and on 

 the reconnaissance line. (See Figure 16.) These sediments are found in Cores 100, 185, 183, 

 and 181 at subsea depths of 55, 54, 62, and 48 feet respectively. Peaty layers in Cores 181 

 and 185 did not contain enough organic material to permit a radiocarbon analysis; tests fo 

 Core 183, however, yielded a date of greater than 39,000 B.P. Carbon-14 analysis of the 

 layer in core 100 suggests original deposition occurred 7,320 B.P., probably in an 

 environment landward of the existing shoreUne. 



The cored sedimentary column changes near Melbourne. Four distinct and continuous 

 Hthologies comprise the bulk of sediment volume extending south from the area. 



Surface sediment from Melbourne to Wabasso (Fig. 16) is generally a poorly sorted 

 mixture of fines and shell gravel (Type C). The mud fraction of this 1- to 2-foot-thick layer 

 is calcareous and of gray color, high water content, and high plasticity. 



Beneath this surficial cover is a relatively thick (3 to 10 feet) and continuous layer of 

 light gray, coarse and muddy, shell sand and gravel. Coarse sand and gravel constitutents are 

 mollusks; Mulinia lateralis is the principal contributor. Fine sand-size grains are both detrital 

 quartz and carbonate fragments. 



The bottom layer in cores 183 through 186 is a light brownish-gray silty fine sand of 

 quartz and carbonate grains, including abundant benthonic foraminifera. Silt content is 

 from white calcareous grains of unknown origin. 



39 



