Lloyd wells in Nassau County are used to furnish public supplies, although a number of indus- 

 trial and estate wells tap the aquifer wherever no other satisfactory water-bearing horizon 

 is present. 



Lloyd sand ■memher — Suffolk County: Although only a few wells have been drilled into 

 the Lloyd sand member in Suffolk County, the small amount of data available indicates that 

 the aquifer is present beneath all of the County. Information on the extent and character of 

 the Lloyd sand in Suffolk County is confined to a few wells located in the northwestern section 

 of the County, two recently drilled test wells at Brookhaven National Laboratory near the 

 center of the County, and two wells on the north fluke in the extreme northeastern part of the 

 Island. In Suffolk, the top of the Lloyd ranges from about 200 to an estimated 1,700 feet below 

 sea level. The aquifer thickens from about 150 feet at Lloyd Neck in the northwestern part of 

 the County to over 300 feet in the southeastern part of the County. Fresh water is obtained 

 from most Lloyd wells in Suffolk, but only salt water has been pumped from Lloyd wells at 

 Crane Neck Point on the northeast shore of Smithtown Bay (well S 91) and at Orient Point 

 (well S 189). All water in the Lloyd sand in Suffolk County is under artesian pressure, and 

 flowing wells may be expected along the north and south shores where the land surface is 

 close to sea level. 



Rarifan -formation — clay member 



The clay member of the Raritan formation on Long Island typically consists of laminated 

 silty and solid clays with subordinate sandy layers. Light and dark gray colored clays are most 

 commonly observed, with beds of red, white, yellow, and mottled clays being less frequently 

 reported. Layers of lignite and pyrite interbedded with carbonaceous clays are found through- 

 out the member over the entire Island. Plant spores, leaves, and lignitized wood are abundant 

 at various depths. These carbonaceous layers have not been traced horizontally for any great 

 distance. Marine fossils have never been reported from the Raritan clay member. 



The clay member covers the Lloyd sand throughout the Island except at the western end, 

 where much post-Cretaceous erosion has occurred. Valleys formed during several cycles of 

 erosions may have cut entirely through the clay in various parts of the Island, and thus possiby 

 afford avenues for downward percolation of water to recharge the Lloyd sand member. Sandy 

 layers within the clay member also probably assist downward movement of water through the 

 ctay member. 



Clay member — Kings County: The limiting line of the Raritan clay member can only be 

 roughly drawn in Kings County due to the lack of data and the uncertainty of the correlation 

 of a number of deep wells in the Flatbush section of the County. The northwestern limit of 

 the clay member appears to roughly parallel the limit of the overlying Magothy (?) foi-mation 

 but in some places it extends somewhat further to the north and northwest. In the southeastern 

 portion of the County, the clay member overlies the Lloyd sand member whereas in a few 

 places in northeastern Kings County, the clay member rests directly upon bedrock. 



The irregularities of the contour lines shown on the accompanying contour map of the 

 Raritan clay member, are due chiefly to the unusual erosional features which characterize the 

 upper surface of the clay member. In northern Kings County accurate correlation of the clay 

 member in well logs is obscured by the lithologic resemblance of the clay member to overlying 

 Pleistocene clays. 



In Kings County the clay member ranges in depth from about 60 feet at Greenpoint in 

 northern Kings to about 500 feet below sea level in southeastern Kings County, and its thickness 

 ranges from about 30 to 220 feet, increasing toward the south. 



17 



