DETAILS OP STRATIGRAPHY 361 



on the opposite side of the river in Illinois and their equivalents elsewhere 

 in the Mississippi Valley. 



It will be convenient, however, to subdivide the Edgewood into three 

 members, as follows : ( 1 ) The Cyrene member, which will include the 

 lower, fossiliferous limestone phase of the formation below the Bowling 

 Green member, exposed 1 to 2 miles east of Cyrene and Edgewood, in 

 Pike County, Missouri, and about 2 miles north of Thebes, in Alexander 

 County, JQlinois; (2) the Noix oolite member, which will refer to the 

 local oolite facies of the formation, which is the equivalent of a variable 

 portion of the upper part of the Cyrene member; and (3) the Bowling 

 Green member, which will embrace the buff or brown, mostly unfossilifer- 

 ous, limestone in the upper part of the formation, corresponding to the 

 strata outcropping near Bowling Green, Missouri. 



The name Channahon limestone will be retained for easy reference to 

 the strata seen only along the Desplaines Eiver 1 mile southeast of Chan- 

 nahon, in Will County, Illinois. This limestone is considered the equiva- 

 lent of some part of the Edgewood formation, but it can not yet be corre- 

 lated with any particular part of this formation because of the complete 

 isolation of the area from other exposures of the Edgewood limestone and 

 the slight difference in its fauna from that of the typical Edgewood lime- 

 stone in eastern Missouri and southwest Illinois. 



Strata representing parts of the Edgewood limestone are nearly coex- 

 tensive with the distribution of the Alexandrian series in the States of 

 Illinois and Missouri. The lower, fossiliferous layers of the formation 

 (Cyrene member) are present near the river in Alexander County, Illi- 

 nois, and over a considerable area in the vicinity of Edgewood and Cy- 

 rene, in Pike County, Missouri, where they are in places overlain by the 

 Bowling Green member. Farther north, near Bowling Green and Mc- 

 Cune Station, the Cyrene member of the Edgewood is mostly absent and 

 the overlying Bowling Green member makes up the greater part of the 

 formation. 



Detailed sections. — An excellent exposure of the lower strata of the 

 Edgewood limestone appears in Illinois along the east bank of the Missis- 

 sippi River, about iy 2 miles north of Thebes, where they occur in the 

 bottom of a low syncline and occupy an old channel eroded in the Girar- 

 deau limestone during the post-Girardeau-pre-Edgewood land interval. 

 The succession of strata at this place is shown in the following detailed 

 section : 



