-31- 



LA SALLE 

 LS. 



10, 



Limestone - light gray to brownish 

 and greenish gray, dense, algal, 

 nodular in places; brachiopods 

 abundant . 



Shale - light greenish gray to 

 dark gray, blocky. 



Limestone - light gray to gray, 

 crinoidal; contains abundant 

 brachiopods. 



Shale - very dark gray to black, 

 soft. 



Shale - black to dark gray, fissile. 



Shale - black to dark gray. 



Coal 



Clay - dark gray, grades downward to 

 light gray; carbonaceous impressions 

 in upper part. 



Limestone - gray to light greenish 

 gray, dense, slabby, fossiliferous. 



Shale - light greenish gray, blocky; 

 contains numerous limestone nodules. 



Fig. 13 - SPRING VALLEY WEST, ravine west of mine dump about 1/2 mile west of 

 Spring Valley. Sh SE% Mh Sec. 33, T. 16 N., R 11 E., Bureau 

 County, Spring Valley Quadrangle. The histogram indicates the number 

 of conodonts found per kilogram of sample; the bars are divided to 

 show ratios between the genera Gondolella (line pattern) , Strepto- 

 gnathodus (white) , and Cavusgnathus (black) . 



