NO. I FORAMINIFERA IN LONG ISLAND SOUND — BUZAS 45 



Several different approaches were used in attempting to draw a 

 generalized sediment map. One consisted of classifying the sedi- 

 ments by their Md<£ into sand, silt, or clay. The result was a map so 

 overgeneralized that it was useless. The percent of sand, silt, and 

 clay at each station was plotted on a triangular diagram in hope of 

 obtaining discrete groups. The plots showed only two major groups 

 with a transitional boundary. Plots of Md<£ vs. o-</>, and Md<£ vs. a<£ 

 also lacked more than two clearly discrete mappable units. The 

 classification of Niggli (1935), adapted to the Wentworth size classes 

 by Pettijohn (1957) and modified by Dunbar and Rodgers (1957), 

 which utilizes the first and third quartiles was finally adopted because 

 it divides the sediment types into objective, manageable (six cate- 

 gories for L.I.S. sediments), and mappable units. The right-hand 

 side of table 11 shows the sediments classified according to Niggli's 

 scheme. 



Examination of figure 20 shows that nearly the entire central area 

 of L.I.S. is composed of clayey silt and silty sands. In traverses 

 2 and 3 more than half of the stations are composed of clayey silt. 

 The sediment in these traverses changes to silty sand as Long Island 

 is approached. Stratford shoal which is a topographic high in the 

 center of the Sound midway between traverses 2 and 3 is composed 

 of pebble sand. Farther east in traverse 4 silty sand is the dominant 

 sediment. The area of silt shown between traverses 3 and 4 is prob- 

 ably of no significance because examination of table 11 shows that 

 with the exception of station 34, the stations in traverse 4 classified 

 as silt differ little from the stations called silty sand. Likewise, sta- 

 tion 10 in traverse 3 differs little from stations 9 and 11 which are 

 classified as clayey silts. The northern coast of Long Island east 

 of longitude 73° is composed of coarse sand. Traverse 5 shows that 

 the area of sand increases as the Sound narrows at its eastern end, 

 and the silty sands become restricted into a narrow band. West of 

 longitude 73° the northern coast of Long Island is irregular and the 

 area of clayey silt shown on the map might have been anticipated 

 from the shoreline configuration. Very little information is available 

 for most of the near-shore areas, but the work of Ellis (1962) shows 

 that the distribution of near-shore sediments is complex. 



Examination of table 11 indicates that most of the sediments are 

 poorly sorted. The silty sands have an average a<f> of 2.3 ; the clayey 

 silts, 2.8. Most of the silty sands are skewed toward the fines, whereas 

 the clayey silts are skewed toward the coarser sizes. The sands are, 

 in general, better sorted and have an average cr^> of 1,5. 



