T. E. Savage — Relations of the Alexandrian Series. 33 



magnesian limestone (Sexton Creek), the lower part of which 

 furnished Pentamerella f manniensis, and Pentamerus cf. 

 ovalis. In the opposite bluff, on the Illinois side of the river, 

 the Sexton Creek limestone containing Pentamerella f man- 

 niensis and Pentamerus cf. ovalis in the basal portion, 

 and Phinopora near verrucosa, Stricklandinia triflesiana, 

 Triplecla ortoni and their associates in a zone 25 feet higher, 

 may be seen overlying the Bowling Green limestone member 

 in several exposures from a place 2% miles north of Pleasant 

 Hill in Pike County southward to 15 miles below Hamburg, 

 in Calhoun County. A typical section of the Edgewood and 

 Sexton Creek strata in this region is given on page 371 of my 

 paper on the Alexandrian series. The same relations of the 

 Bowling Green limestone member to the underlying oolite 

 phase of the Edgewood below and the overlying Sexton Creek 

 limestone are exposed at a number of places in Jersey County, 

 west and northwest of Grafton. 



In northeast Illinois the Pentamerella f manniensis zone of 

 the Sexton Creek limestone occurs above the upper brown 

 Bowling Green limestone member of the Edgewood formation 

 in the exposures along Kankakee river below Custer Park, in 

 Kankakee County ; along the Des Plaines river southeast and 

 south of Channahon ; and near Essex, in Will County, 

 Illinois. 



It is now known that the Essex limestone exposed in the 

 bank of Horse Creek, near the town of Essex- in Will County, 

 Illinois, corresponds to the limestone removed in the excava- 

 tion two miles below Channahon, and to that exposed in the 

 lower part of the quarry along the Des Plaines river 1^ miles 

 farther south. The chert masses bearing Pentamerallaf 

 manniensis, in number three of the published section of the 

 Essex limestone, have been found to have come from a horizon 

 some feet higher, from which they slumped down to the place 

 where they now rest upon the lower part of the brown 

 limestone equivalent to the Bowling Green member of the 

 Edgewood at that place. With these discoveries, the Essex 

 limestone is seen to represent a horizon of the Edgewood a 

 little higher than the old Channahon limestone previously 

 known, and it is overlain by the brown, almost barren magnesian 

 limestone corresponding to the Bowling Green member of the 

 Edgewood, which, in this vicinity, as along the Kankakee 

 river below Custer Park, and along the Des Plaines river 

 south of Channahon, and in the river bluff below Clarksville, 

 in Pike County, Missouri, and in Pike, Calhoun and Jersey 

 Counties, Illinois, is unconformable overlain by the Sexton 

 Creek (Brassiield) limestone containing the fossils already 

 mentioned. 



Am. Jour. Sci.— Fourth Series, Vol. XXXVIII, No. 223. -July, 1914. 

 8 



