THE CHESTER SERIES IN ILLINOIS 293 - 



the Yankeetown is rather Hght colored, and it may be detected in 

 many places by the presence of the fragments of nearly white chert 

 scattered through the surficial deposits. 



The thickness of the Yankeetown in the Mississippi River 

 counties nowhere exceeds 20 feet, and in places it is perhaps less 

 than 10 feet thick. In spite of its thinness, however, the Yankee- 

 town is very persistent, and is uniform in its characters from a point 

 in St. Clair County not more than eight or nine miles south of East 

 St. Louis, to near Lithium in the northern part of Perry County, 

 Missouri. 



Where the Lower Chester formations reappear in Union County, 

 Illinois, the horizon of the Yankeetown is occupied by a sandstone 

 formation quite different in character from the Yankeetown, which 

 has been named the Bethel sandstone by Butts from outcrops in 

 Kentucky. This sandstone holds its position in the Chester sec- 

 tion from Union County to Hardin County, except where the out- 

 cropping belt is interrupted by faulting, although in southern John- 

 son County there is a short interval where the formation is entirely 

 lacking. In the first section in Union County, east of Anna, where 

 the Bethel sandstone has been observed, its thickness is compa- 

 rable to that of the Yankeetown in Monroe and Randolph counties. 

 It is certainly not greater than 20 feet, and perhaps does not 

 exceed 10 feet. Traced to the eastward across the southern 

 counties to the eastern edge of Johnson County, the Bethel nowhere 

 exhibits a thickness greater than 25 or 30 feet, and at one locality 

 at least, in Johnson County, it is lacking altogether. In western 

 Pope County the formation is interrupted by a great, down-dropped 

 fault block, and where it is exposed to the east of this fault block 

 it is considerably thicker, and continues to increase to the east, 

 attaining a thickness of at least 100 feet in southwestern Hardin 

 County. 



This sandstone continues southward across the Ohio River into 

 Kentuck}^, and it is this formation which Ulrich mistakenly con- 

 sidered to be the equivalent of the Cypress sandstone of Engel- 

 mann, an error which he has acknowledged and corrected in his 

 latest contribution to the subject.^ 



^ Formations of Chester Series in Western Kentucky (1917), p. 8. 



