PLEISTOCENE MOLLUSC A FROM ILLINOIS 47 



Feet 



8. Fine sand, no pebbles, yellow, highly calcareous * 2| 



7. Calcareous till, banded, yellow and grayish, limestone pebbles, 



compact li 



6. Blue, gummy clay, nearly gritless in some places and pebbles up to 



I inch in others, highly calcareous. 



1 2 

 3 3 



5. Fossiliferous loess, grayish to yellowish, rusty streaks near base, 



calcareous throughout, sand streaks, cross-bedded, dip southerly. . 5 

 4. Stratified yellow sand and gray silt with few pebbles, few fossils, dis- 



coidal, calcareous i\ 



3. Light blue silt, pebbly, some limestone pebbles, highly calcareous; 



may be till i 



2. Sandy to gravelly till, yellowish to rusty, limestone pebbles, matrix 



calcareous 2 



I. Probably till, gray with pinkish tinge, calcareous; steam shovel has 



worked stratum giving steeper slope than above section 7 



Nos. 6 to 10 include the Wisconsin drift sheets; Nos. i to 3 

 represent Illinoian till; Nos. 4 and 5 indicate an interglacial 

 interval between the deposition of these tills. The sand and silt 

 (No. 4) may represent the Sangamon, and the loess (No. 5) the 

 Peorian, although there appears to be no break between them. 

 No. 4 has yielded two species of fresh water mollusks; Planorhis 

 altissimus and Calha palustris, represented by but a few specimens. 



STATION NO. 6 



Locality: Same as Station No. 5. 



Material: Taken from the fossiliferous loess No. 5 of the previ- 

 ous section. Separate collections were made from both the yellow 

 and gray loesses, the mollusks in both being of the same species. 



Stratigraphic horizon: Possibly Peorian loess. 



MOLLUSCAN LIFE 



Succinea vermeta, the common Succinea of the loess, occurred 

 somewhat more abundantly in the yellow than in the gray loess. 

 Mr. B. B. Cox, a student in the University of Chicago, collected 

 mollusks from the loess and other deposits, though he did not dis- 

 criminate betweeen the deposits. He found in addition to the 

 above Sphyradium edentulum alticola, a typical Peorian loess fossil, 

 represented by one specimen. 



