ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 487 



Batavia West Section 



Batavia W Section, measured in auger hole situated in the SE^SE^ 

 sec. 24, T. 39 N. , R. 7 E., about 2.75 miles WSW Batavia, 

 Kane County, Illinois. 



8. Dark brown peat; no fossil shells except in lower 

 few inches. Radiocarbon date from lowermost 2 

 inches of interval, 1750 ± 100 B.P. (ISGS-131) 

 (Coleman, 1974) 



7. Gray-tan silt, clay, and marl; contains 



abundant fossil mollusks 



6. Gray-tan marl with abundant fossil mollusks 



and plant remains 



5. Gray-tan marl and clay; plastic and wet; 



abundantly fossilif erous 



4. Dark gray marl and silt, some undecayed peat; 



fossilif erous , very wet, almost semifluid . . . . 



3. Dark gray fossilif erous silt, with small amount 

 of plant material; contains small masses of 

 sterile gray clay 



2. Dark gray, sandy, nonfossilif erous clay; 



plastic and very wet 



1. Base in sterile gray clay, no pebbles 



Total 



Thickness 

 (feet) 



4.5 



0.5 

 2.8 

 2.5 

 2.1 



3.3 



1.6 



0.6 



17.9 



Generalities 



Augering was done with a sandspoon because of the almost semifluid 

 condition of the bog sediments. Samples were removed from the spoon and col- 

 lected in plastic bags, each of which was labeled with appropriate data. The 

 collected samples were subsequently washed over wire screens; the residue was 

 dried and the fossil shells were sorted from the residue. Although no attempt 

 was made to collect samples of uniform size, most of them contained about 

 1,000 shells. A few fossil seeds were recovered; all the samples, except the 

 sterile clay and sand at the base of the borings, contained many ostracods and 

 even more diatoms. 



It is judged that most of the fossil shells at each of the two localities 

 collected on the bottom of a quiet lake; evidence for this includes the apparent 

 lack of sorting of fine sediments and the fact that in all borings and at nearly 

 all levels many small pelecypods were recovered with the two valves still united, 

 despite the operations of boring and the later treatment of the samples. However, 



