Sediment designated type I is a medium-grained, clean quartz sand. 

 Actual size ranges from about 0.215 to about 0.707 millimeter (2.2 to 

 0.5 phi). Sorting of the sand ranges from 0.35 to 0.80, which is within 

 the well sorted and moderately well sorted classification (Friedman, 1962). 

 Characteristics of the grain-size distribution and significant grain types 

 for all sediment classifications are summarized in Table 4. The dominant 

 components of all sands are detrital quartz and feldspar. Individual 

 quartz grains are subrounded to subangular; most are clean, but frosted 

 and milky grains are not uncommon. Feldspar grains, including rare twins, 

 are easily identifiable under reflected light on the basis of color and 

 cleavage. Samples contain several percent each of heavy minerals and 

 rock fragments. Glauconite is present in trace quantities and mica is 

 virtually absent. Approximately 1 to 2 percent of the sand is composed 

 of biogenic calcium carbonate. Individual grains of carbonate are white 

 and coarse sized; the majority are derived from mollusk shells. Also 

 present in trace quantities are benthonic foraminifera and ostracods. 



Type II sediment is a fine-grained, well sorted to moderately well 

 sorted, quartz sand that is similar to type I sand in all but two respects, 

 One significant difference is the finer modal size (Table 4) . A second 

 difference is the composition of the biogenic fraction of the two sediment 

 types. Benthonic foraminifera are more abundant in the fine sand than in 

 the medium sand. Dominant types are Elphidium sp. and Quinqueloculina sp. 

 Fragments of molluskan fauna are less abundant and more fragile than in 

 the medium-grained sand, and spines and fragments of echonoids are present 

 in small quantities. Both sands (types I and II) can be described as 

 well-sorted subarkosic arenites (Table 4). 



Type III sediment is also fine sand, but it differs from the other 

 sands slightly in modal size and differs significantly in sorting. The 

 sand is very fine to fine grained and poorly sorted (1.4 to 2.0) 

 (Friedman, 1962). Composition is similar to that of the fine, clean 

 sands of type II with two minor exceptions. Echinoid fragments are more 

 common and plant material in the form of grains and fibers is present. 



Type IV sediment, which is a very poorly sorted silt or slightly 

 sandy mud, contrasts sharply with the clean sands (types I and II). The 

 dominant size of particles is 0.625 to 0.039 millimeter (4 to 8 phi), but 

 both clay particles (<0.039 millimeter or >8 phi) and sand grains (>0.625 

 millimeter or >4 phi) are present in varying proportions. Grain types 

 are difficult to identify under reflected light because of their small 

 size, but the majority are terrigenous silicate grains. Benthonic 

 foraminifera are common; dominant species are Ammonium sp., Quinquelocu- 

 lina sp., and Elphidium sp. Plant fibers and debris are common in places. 



Type V sediment is a classification comprising several different 

 sediment types that are restricted in thickness and distribution. In- 

 cluded within this group are organic-rich silts, clean sands, and poorly 

 sorted gravels. The organic-rich silt is a poorly sorted medium silt; 

 the organic fraction is unidentifiable plant remains. At least four 

 cores contained this type of sediment, and two of them contained enough 



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