Because of the geographic position of the study area the obvious major sources of marine 

 sediments are the glacial moraine to the north and Coastal Plain strata underlying the shelf 

 and composing the New Jersey landform to the west. Relative mineral abundance was found 

 to be a definitive criteria in distinguishing between these two most likely sources. Colony 

 (1932) determined that both green and black glauconite are an abundant constituent of the 

 Upper Cretaceous and Tertiary formations restricted to New Jersey. Cretaceous beds 

 reportedly underlie Long Island, buried by thick Pleistocene deposits; consequently, 

 glauconite is not found in the beach sands of Long Island. In the cores east of mainland New 

 Jersey glauconite grains averaged about 5 percent of the total population, while the shelf 

 sands east of Sandy Hook contained 1 to 2 percent glauconite. There was a noticeable 

 decrease northward from Long Branch toward Long Island to where no glauconite was 

 present in the cores immediately south of Rockaway Beach. 



Of the opaque heavy minerals in the fine sand-size class the abundance of magnetite was 

 an important indicator of source. Magnetite is an ubiquitous constituent in Long Island 

 beach sands, carried south by glacial processes from the igneous and metamorphic terrain to 

 the north. In New Jersey magnetite is nearly absent, except for trace amounts near some 

 coast jetties constructed of blocks of igneous and metamorphic rock. Sediment samples 

 immediately south of Coney Island and Rockaway Beach contained as much as 10 percent 

 opaque heavy minerals while samples south of Sandy Hook contained only about 1 percent. 



Feldspar was found to be an equally good source-area indicator. All core-top sediment 

 north of Sandy Hook and on the Rockaway Beach shelf contained at least 8 percent, and 

 some samples as high as 25 percent feldspar. New England Piedmont terrain is characterized 

 by rocks rich in feldspar. Because weathering processes are predominantly mechanical, the 

 rocks tend to disaggregate into constituent minerals with a minimum of decomposition. 

 Core-top samples east of the New Jersey coast were found to average only 2 to 5 percent 

 feldspar. In contrast, Coastal Plain strata have undergone extensive chemical weathering 

 resulting in degradation of the unstable feldspars. This data supports other evidence that the 

 Long Island shelf sediments are from northern glacial deposits and that New Jersey shelf 

 sediments are from Coastal Plain strata. 



In samples containing a gravel fraction the pebble compositions supported the other 

 source -area data. Material east of New Jersey consists primarily of rounded, iron-stained 

 milkv quartz similar to the gravels found onshore in several Coastal Plain formations. Gravel 

 immediately south of Long Island contained a large percentage of quartz, but also in 

 abundance were rock fragments of igneous and metamorphic origins which ranged from very 

 angular to round. The gravel immediately south of Rockaway Beach is similar to the 

 moraine material covering Long Island and areas to the west. 



Grain textures examined by a plane light binocular microscope did not result in any 

 definitive criteria to distinguish source origins. Examination of individual grains by electron 

 microscope has been successfully used by several researchers in determining sediment origins 



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