PLEISTOCENE MOLLUSC A FROM ILLINOIS 49 



Material: The bluff shows the following section: 



Feet 



5. Soil and angular "float" i- ii 



4. Silt, structure mostly obliterated, leached, conforms to the present 



slope 1-3 



3. Sands and silts, laminated and thin-bedded, minor lens and pocket 

 structure; clay yellow and brown; red granite bowlder i foot in 

 diameter occurs about 10 feet above creek bottom on the north 



side near the base of this horizon; maximum 22 



2. Blue silt, fossiliferous, some brown sand 6-8 



I. Coarse, angular gravel, discontinuous in the middle portion exposed 



(above water level) o- 2I 



Stratigraphic horizon: Nos. 2, 3, and 4 are believed to be of 

 Wisconsin age, formed in backwater from the Mississippi, but there 

 is reason to assign it to Peorian age or earlier. 



MOLLUSCAN LIFE 



Mollusks were collected from both the silts and the sands, as 

 follows : 



Silts Sands 



Succinea vermeta, abundant. Succinea vermeta, abundant. 



Vertigo modesta, rare, i spec. 



Pyramidula shimekii, rare, 3 spec. Pyramidula shimekii, rare, i spec. 

 Galba parva, not common. 



The land shells (including all except Galba) are characteristic 

 of the Peorian loess. Their presence (especially Pyramidula 

 shimekii) in this deposit beneath nearly 25 feet of other material 

 would indicate an earlier age than the Wisconsin. The till in 

 Carroll County is of Illinoian age, and it seems probable that the 

 material above the till, especially Nos. 3 to 5 of the section, while 

 deposited by the Wisconsin waters, really covered up life-remains 

 that lived during the Peorian or Sangamon interglacial period. 



In the sands and silts of stratum No. 3 (Station No. 9) three 

 species were found, Succinea vermeta, Vertigo modesta, Galba parva, 

 the Succinea being the only abundant species, the others very rare. 



STATION NO. 10 



Locality: Same as Station No. 8. 



Material: Creek bank 5 feet high on south side of meander 

 curve shows the following section: 



