270 LIFE OF THE PLEISTOCENE 



Hard blue till (Illinoian) 25-30 feet 



Black muck (Yarmouth) 20 " 



Sand and gravel at bottom (Buchanan gravels) x 



At Bloomington, McLean County, a well section passes thru three intergla- 

 cial intervals, 81 as noted below: 



1. Surface soil and brown clay (Wisconsin) 10 feet 



2. Blue clay (Wisconsin) •. 40 " 



3. Gravelly hard pan (Wisconsin) 60 " 



4. Black mold with pieces of wood (Sangamon) 13 " 



5. Hard pan and clay (Illinoian) 89 " 



6. Black mold, etc. (Yarmouth) 6 " 



7. Blue clay (Kansan) 34 " 



8. Sand, buff and drab, with fossil shells (Aftonian) 2 " 



9. Coal shale (Coal measures) x 



Depth of well 234 " 



Bannister reports Heliciua occulta from No. 8, which is suggested might 

 be loess. Another shaft, a little over a mile distant, passed thru materially 

 the same strata, with only local variations in thickeness. 



Near Coatsburg, Adams County, a coal boring showed the following series 

 of strata: 82 



1. Soil and yellow clay (loess) 6 feet 



2. Gray or ashy clay, resembling a soil (Sangamon) 4 " 



3. Yellow till, becoming gray or blue near bottom (Illinoian) 10-15 " 



4. Blue-gray till (Illinoian) 70-75 



5. Black soil (Yarmouth) 2^ " 



6. Stratified clay (Yarmouth) 6 " 



7. Tough blue clay (Kansan) 20 " 



Depth of well 118 



Worthen 83 reports wood and bones from No. 5, and lacustrine and fluviatile 

 shells from No. 6. The loess is said to contain land shells. 



a. Silveria Formation 



Hershey 84 has given the name Silveria to certain stratified silt-like clays 

 which underlie the Illinoian till in northwestern Illinois. These are referable 



81 Bannister, Geol. Illinois, IV, p. 178; Leverett, 111. Glacial Lobe, pp. 108, 694. 

 8 -0;>.a7.,p.716. 



83 Geol. Illinois, IV, pp. 46-47. 



84 Amer. Journ. Sci., (iv), II, pp. 324-330, 1896, Leverett, Illinois Glacial Lobe. dd. Ill— 

 118. 



