400 ILLINOIS STATE ACADEMY OF SCIENCE 



of chert. It is entirely eroded from the top of th« anti- 

 cline and is exposed well down on the flanks. The maxi- 

 mum thickness sho^ii in well records is 185 feet. 



Salem Limestone: 



The Salem limestone, like the overlying St. Louis, is 

 also eroded from the top of the anticline. Where ex- 

 posed, it consists of a fine and coarse grained, moderately 

 hard, gray-white and speckled limestone. Locally it 

 contains chert, and is commonly oolitic. As noted from 

 well records its thickness varies up to 140 feet. 



Warsatv Limestone and Shale: 



The Warsaw outcrops on the flanks of the anticline, 

 but it is entirely eroded from th« crest. It consists of 

 gray and buff, crystalline limestone, moderately hard, 

 and locally argillaceous, and interbedded with thin lay- 

 ers of shale. In the upper beds of the formation Spirifer 

 ivnshingtonensis and Prodiictus magnns are abundant. 

 Its thickness ranges up to 125 feet. 



Keohuk-Burlington Limestone: 



The Keokuk-Burlington is the oldest formation ex- 

 posed on the anticline. It consists of coarsely crystal- 

 line, or granular, white limestone with much interbedded 

 blue-white chert. Its thickness varies from a few feet 

 on the top of the anticline to about 240 feet well down 

 on the flanks. 



Kinderhook Limestone and Shale: 



The Kinderhook fonnation has two phases, the upper 

 shaly phase and the lower limy phase. The upper phase 

 is not every where present; in fact it is more commonly 

 absent than present, and so far as known does not out- 

 crop in the vicinity of the anticline. It appears more 

 commonly in the logs of wells drilled near or on the axis 

 of the anticline, and has a thickness of from 32 to 110 

 feet, with an av-erage of 70 feet for the eight wells in 

 which it is logged. 



As indicated by the disparity between the maximum 

 and minimum thicknesses, the shaly portion of the Kin- 



