Amorphous carbonate modules and weathered molds are often included in these clays. 

 Whether a correlation exists between all greenish-colored clays has not been determined. If 

 so, these deposits may underhe extensive areas of the inner shelf south of St. Augustine. 



A few samples of gray, black, and brown fissle clay have been obtained from scattered 

 locales within the study area and appear to be unrelated localized deposits. 



Brown silty fine sand similar in character in type F sediment occurs in isolated patches 

 seaward of the type F deposit on the shoreface and continuous innermost ramp. There is no 

 evidence that these isolated deposits are continuous with the type F deposit but they 

 probably formed under similar conditions. 



Very coarse shelly quartz sand and granules with pebbles and granules of phosphorite 

 occur in a few cores from various parts of the study area. This material has been found 

 directly overlying type L calcarenite and probably contains a residual lag formed by 

 weathering of the underlying type L material. Since it occurs in only a few widely scattered 

 cores this material is probably present only as an erosional remnant of a previously more 

 extensive deposit. 



Other unclassified sediments occurring in only one or two cores include hme mud, brown 

 and green friable sandstone, peat, chalky calcareous pebbles, chalky friable Umestone with 

 casts and molds of pelecypods, and reddish brown sand with carbonized wood fragments. 

 2. Sediment Distribution on the Inner Shelf. 



a. Surface Distribution Patterns. The dominant characteristic of surface sediments on 

 the north Florida inner shelf is the abundance of fine quartz sand. Over 90 percent of the 

 sediments lying landward of the 70-foot contour are very fine to medium sand size (0.088 

 to 0.35 millimeters; 3.5 to 1.5 phi); and composed principally of quartz. Surface sediments 

 not included in this generahzation comprise a very fine silty quartz-sand facies, an 

 occasional coarse, quartz-sand deposit, and some surface exposures of carbonate-rich quartz 

 sands. 



Overall distribution patterns of surface sediment on the inner shelf floor of the study 

 area are largely a result of the thin and discontinuous nature of Pleistocene and Holocene 

 sediments. Patches of older sediment are exposed where tlie overlying younger layer or 

 layers are missing due to erosion or nondeposition. Thus, adjoining patches of the shelf 

 surface often contain sediments deposited at different times and under different 

 environmental conditions. Within the study limits, sediments as old as probable late Miocene 

 (Type M) and as young as Holocene (Types A and F) are locally exposed in adjacent surface 

 patches. Boundaries between these patches are siiarp and not gradational as with lateral 

 facies changes in contemporaneous deposits, and both the lithologic character and faunal 

 assemblages of the separate patches may be strikingly dissimilar. In addition to the exposure 

 of sediments of different age at the surface, there are lateral gradations within 

 contemporaneous deposits and the disposition of surface sediments in detail is locally 

 complex and irregular. However, there is a relatively uncomphcated dominant sediment 



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