LEGEND 



HB T VDe DI - coarse to very coarse sond and gravel ( <■ I phi ) 

 I I Type 31 -medium lo coarse sond ( 2 to I pfii) 



Type II - very fine lo medium sond ( 4 lo 2 pni ) 

 Y////A Type I - sill and clay lo very line sond (24 phi ) 



• CERC Cores 



■ ALPINE Cores I 1965) 



1 UARl Cores (1970) 



Figure 13. Eighty cores analyzed to show the four primary sediment types 

 present in the top 5 meters of the sea floor. 



sorting (Table 4), and by color of the dried sample, into four major sediment 

 types: (a) type I sediments composed chiefly of clayey silts and very fine 

 sandy silts (termed mud in some reports); (b) type II materials of very fine- 

 to medium-grained sand, generally moderately to well sorted; (c) type III 

 sediments of medium- to coarse-grained sand, moderately sorted, and (d) type 

 IV lithology classified as coarse and very coarse sand and gravel, pebbles, 

 and cobbles. The distribution of the major lithologies in the cores is shown 

 in Figure 13; the surface distribution is shown in Figure 14. 



a. Primary Sediment Classes . 



(1) Sediment Type I. The sediments are composed of slightly cohesive 

 and soft clayey silts and sandy silt with grain diameters smaller than 0.063 

 millimeter (>4 phi). Figure 14 shows that type I sediments are most abundant 

 in the deeper parts of the Sound and along the Connecticut shore, except along 

 parts of the coast where glacial sand and gravelly deposits are actively 

 eroded by waves. Type I materials originate from rivers, primarily the 

 Connecticut and Thames, that drain glaciated terrain to the north and have 

 brought fine-grained sediment to the Sound for about the past 12,000 years. 

 In addition to contributions of the rivers, Bokuniewicz , Gebert, and Gordon 

 (1976) believe that significant amounts of fine-grained material are trans- 

 ported from Continental Shelf areas south of Long Island and are carried into 

 the Sound and distributed westward by flood tidal currents. Cores 11, 13, 30, 

 32, 37A, 39, 45, 47, 50, 52A, 57, 59, 62, 73, and 77 show fine-grained sedi- 

 ment overlying sandy sediment, and patches of opaqueness on the acoustic 

 profiles suggest that pockets of type 1 sediment with high gas content are 

 common in deeper parts of the basins. 



33 



