THE CHESTER SERIES IN ILLINOIS 295 



Yankeetown for a thickness of about 10 feet there is a series of 

 bluish, calcareous shales with platy limestone layers, and above the 

 red bed there are other calcareous shales which pass up into lime- 

 stones, thinly bedded and shaly below, becoming more massive 

 above, these beds being succeeded by more shale beds some of 

 which are variegated red and blue in color. Although there are 

 other reddish or at least variegated shale beds elsewhere in the 

 Chester section, there is no bed anywhere in the series in Illinois 

 that can be mistaken for the deep-red clay bed of the lower part 

 of the Paint Creek formation. Not only is this bed recognizable 

 in surface outcrops, but it can be easily detected in many well 

 records. 



The red shale bed of the Paint Creek formation outcrops at 

 intervals throughout the Chester belt from St. Clair to Randolph 

 counties, the northernmost exposure being about one mile northwest 

 of Millstadt. The formation continues across the Mississippi River 

 into Missouri, and the southernmost exposure is in northern Perry 

 County of that state. Between these two localities the same red 

 shale bed is exposed at many localities. It is exceedingly uniform 

 in its characteristics, and where it is met with it is absolutely impos- 

 sible to mistake it for any other bed in the Chester series. 



The limestones of the Paint Creek formation are similar in 

 lithologic character to many other limestones of the Chester series. 

 The several beds are separated by shale layers varying in thickness 

 from an inch or so to several feet, and the limestone beds them- 

 selves vary in thickness from less than one foot to three or four feet. 

 Most of the shale beds are more or less calcareous, but above the 

 main mass of limestone there is a considerable body of shale in 

 many sections that is little or not at all calcareous, and is varie- 

 gated red and blue or purple. Most of the limestone beds are 

 crystalline, some are quite pure and white, others are more impure 

 and much darker in color. 



In the southern counties of the state, from Union to Hardin, 

 the Paint Creek is represented mostly by shales, with only subor- 

 dinate limestone laj^ers, commonly very thin and exhibiting con- 

 siderable variation in the entire amount that is present. The 

 deep-red shale bed is wanting in the section in these southern 



