1 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 487 



center of the original basin. Sediments were penetrated to a depth of 20 feet, at 

 which depth sidewall collapse prevented further augering; till was not encountered 

 but the paucity of molluscan fossils, increase in percentage of clay, and occur- 

 rence of pebbles indicated the nearness of the base of the bog deposits. 



Strawn Northeast Section 



Strawn NE Section, measured in auger holes in the SW^SW^SE^ 

 sec. 32, T. 28 N. , R. 8 E., Livingston County, Illinois. 



Thickness 

 (feet) 



5. Black, highly fossilif erous organic muck, partially 

 exposed in wave-cut bank; contains some silt and 

 very fine sand. Radiocarbon date from near base 

 of bed, 2640 ± 75 B.P. (ISGS-161) 2.0 



4. Black organic muck; fine sand, silt, clay, much 

 organic debris, and abundant molluscan fossils. 

 Radiocarbon dates from near base of interval, 

 2330 ± 75 B.P. (ISGS-162A) and 2370 ± 100 B.P. 

 (ISGS-162B) 4.0 



3. Dark gray marl (lighter gray near base of unit); 

 fine sand, silt, clay, much organic debris, and 

 many molluscan fossils. Radiocarbon date from 

 near base of interval, 7760 ± 84 B.P. (ISGS-164) . . 4.0 



2. Gray marl; fine to medium sand, silt, and clay; 



plastic when wet; contains a few pebbles to ^ inch 

 diameter; abundant plant remains and fossil mol- 

 lusks declining in abundance toward base of unit. 

 Radiocarbon date from near base of interval, 

 8940 ± 80 B.P. (ISGS-167) (Coleman, 1974) 4.0 



1. Gray sand; silt and clay mixed with numerous 



pebbles; contains a few mollusks and plant remains 



in upper part; sterile toward base in glacial till 



and/or consolidated outwash. Organic materials 



too sparse for radiocarbon date 3.0 



Total 17.0 



BATAVIA WEST LOCALITY 



The Batavia West Section is also described from a hand-auger boring; the 

 boring is situated along the northwest border of a depression that extends for more 

 than a mile in a southwesterly-northeasterly direction. All of the depression is 

 a peat-covered bog, except for Nelson Lake, which occupies part of the 



