DETAILS OF STRATIGRAPHY 371 



Sexton Creek time these strata have been denuded from a considerable 

 part of eastern Missouri. 



Detailed sections. — The lower layers of the Sexton Creek limestone, 

 containing Pentamerella f manniensis, are 'present south of Clarksville, 

 in Pike County, Missouri, and across the Mississippi Eiver near Belle- 

 view, Illinois. The Sexton Creek limestone is well developed in Calhoun 

 and Pike counties, Illinois, as shown in the following section of strata 

 exposed in the vicinity of Hamburg and Pleasant Hill : 



Section of Strata in the Vicinity of Hamburg, Illinois 



5. Middle Devonian (Iowa Hamilton) limestone: Coarse-grained, gray 

 limestone, containing Spirifcr iowensis and other fossils of the 



Iowa Hamilton. . . . 4 



A long break in deposition. 

 4. Sexton Creek (Brassfield) limestone: Hard, gray limestone in layers 

 6 to 30 inches thick, containing the greater number of fossils 



listed in column number 1 of the table on page 372. '. 48 



A break in deposition. 

 2,3. Edgewood limestone: 



3. Yellow to brown limestone which on weathering breaks into thin 



slabs in an almost vertical direction; fossils few (Bowling Green 



member) 16 



2. Light gray oolite containing fossils similar to those in the middle 



parts of the oolite at Louisiana, Missouri (Noix oolite member) . . 3% 

 A break in deposition. 

 1 . Maquoketa or Orchard Creek shale : Bluish, plastic shale, without 



fossils, exposed 7 



The basal layers of the Sexton Creek limestone in this region, both in. 

 Missouri and Illinois, are marked by numerous shells of Pentamerella ? 

 manniensis Foerste and a species of Pentamerus. A narrow zone, 18 to 

 20 feet below the top of the formation, contains Ehinopora near verru- 

 cosa, StricMandinia triplesiana, Stricklandinia n. sp., and Triplecia 

 ortoni. The upper 10 feet of this limestone furnished Syringolites cf. 

 huronensis and Spirifer radiatus. The fauna of the Sexton Creek lime- 

 stone in this vicinity is shown in the table of fossils on a later page. 



In northeast Illinois the Sexton Creek limestone is thought to be pres- 

 ent over a considerable area in Will and Kankakee counties. A succes- 

 sion of strata very similar in that described in (lie last section occurs 

 along I lie easl bank of Kankakee River, :> to 1- miles below Custer Park. 

 in Will County, as shown in the section given below: 



Section of Strata <iloii<r Kankakee River, below Custer Fork 



Feet 



4. Sexton Creek (Brassfield) limestone : Hard, gray, rather massive 



limestone, containing many fossils ;it certain Levels 18-28 



a probable break in deposition. 



