TABLE 3. MAJOR HYDROGEOLOGI C UNITS OF THE GROUND-WATER RESERVOIR 



ON LONG ISLAND, NEW YORK 



Geologic unit 



Upper Pleistocene 

 depos i ts 



Hydrogeo!ogic 

 uni t 



Upper glacial 



aqu ifer 



Approximate maximum 

 thickness (feet) 



600 



Depth from land sur- 

 face to top (feet) 



0-50 



Gardiners Clay 



Gardlners Clay 



300 



50-^00 



Jameco Gravel 



Jameco aquifer 



300 



100-550 



Hatawan-Group 

 Magothy Formation 

 undifferentiated 



Magothy aquifer 



1,100 



0-600 



Clay Mem- 

 ber 



Rar i tan 



Forma- 

 Tion 



Lloyd Sand 

 Member 



Rar i tan clay 



Lloyd aquifer 



300 



500 



0-1,500 



200-1,800 



Adapted from Franke and McClymonds (1972) and Jensen and Soren (in press) 



j_/ Hydraulic conductivity denotes how readily water can move through porous material. 



0-2,700 



28 



