354 



THE ILLINOIS GLACIAL LOBE. 



The combined thickness of the several sheets of drift has been deter- 

 mined at various points along the line of this morainic system, while at 

 other points wells have been sunk to great depth without reaching the 

 bottom of the drift. The rock surface beneath the drift appears to be quite 

 uneven, there being a known range from about 100 feet above the level of 

 Lake Michigan to more than 100 feet below the surface of the lake. The 

 following list of deep borings sets forth the variations in the thickness of the 

 drift and the elevation of the rock surface: 



List of borings showing thickness of drift along the Valparaiso morainic system. 



At Ivanhoe. Illinois, on crest 



Near Lake Zurich, on crest 



At Lake Zurich, 20 to 30 feet below crest 



Hainesville, near crest 



Gilmer, near crest 



Crest east of Wauconda 



Crest south of Barrington 



Barriugton, 40 to 45 feet below crest 



East of Elgin, near crest - 



Palatine and vicinity 



Near Schaumberg, along crest 



Arlington Heights, about 150 feet below crest 



North of Arlington Heights, 20 to 30 feet above station . 



Near Spaukliug, about 50 feet below crest 



Bartlett, 10 to 20 feet below crest 



Ontarioville, near crest 



Eoselle, about 50 feet below crest 



Crest south of Bloomingdale 



Itasca 



Bensenville 



Elmhurst 



Turner Junction 



Crest east of Najierville 



Downer's Grove 



Crest east of Downers Grove 



Near Clarendon Hills , 



Crest northwest of Lemont 



Crest of moraine east of Lockport 



Near Spencer 



Elevation 

 of well 

 mouth. 



Feet. 

 290 



a 267+ 

 240+ 

 287+ 

 213+ 

 230+ 

 315+ 

 254 

 220-240 

 100-170+ 

 190+ 

 128 

 190 

 120 

 100+ 

 140+ 

 100+ 

 162 

 72+ 



116 



115+ 

 113+ 

 159 

 160+ 

 150 

 115+ 

 81 



820 

 850 

 850 

 818 

 850 

 750 

 825 

 700 

 725 

 770 

 800 

 815 

 770 

 800 

 692 

 677 

 688 

 765 

 740 

 720 

 750 

 755 

 740 

 725 

 710 



Elevation 

 of rock 

 surface. 



Feet. 

 510 



(?) 

 (?) 

 (?) 

 (?) 



(?) 

 (?) 

 564 

 610 

 650 

 (?) 

 572 

 535 

 650 

 (?) 

 (?) 

 (?) 

 638 

 (?) 

 580 

 590 

 649 

 (?) 

 (?) 

 591 

 (?) 

 590 

 (?) 

 629 



a Where the + sign is affixed the rock is not reached. 



