362 T. E. SAVAGE ALEXANDRIAN SERIES IN MISSOURI AND ILLINOIS 



Section exposed along the River iy 2 Miles ~Sforth of Thebes 



Feet In. 

 4—10. Edgewood formation (Cyrene member). 



10. Heavy layer of gray, coarsely granular limestone, oolitic in the 

 upper part, containing Lyellia thebesensis. Rhijnchotreta the- 

 besensis, Whitfield ella Pillingsana, Metapolichas breviceps var^ 



clintonensis, and other fossils 3 6 



9 . Rather soft, gray shale, without fossils 1 2 



8. Dark gray, argillaceous limestone or calcareous shale, in two 

 layers each about 6 inches thick, separated by a 2-inch part- 

 ing of softer shale ; the calcareous layers contain the fossils 

 Schuchertella propinqua, Whitfieldella ovoides, andDalmanites 



danai 1 3 



7. Rather soft, gray shale, without fossils 1 6 



6. Layer of somewhat fissile, fine-grained, argillaceous limestone 



containing few fossils 1 6 



5. Layer of rather hard limestone having a 2-inch band of chert 



at the top ; no fossils found 8 



4. Layer of conglomerate consisting of fragments of Girardeau 

 limestone from 2 to 12 inches in diameter embedded in a 

 matrix of fine-grained limestone ; in some places this member 

 appears to be composed of calcareous concretions surrounded 



by softer, bluish-gray shale 2 6 



A break in deposition. 

 3. Girardeau limestone: Hard, fine-grained, brittle, dark colored 

 limestone, with fossils characteristic of the Girardeau forma- 

 tion 2 6 



A break in deposition. 

 2. Orchard Creek shale (Richmond) : Bluish-gray, calcareous 

 shale, containing 1- to 2-inch bands of shaly, concretionary 



limestone, 4 to 6 inches apart ; 18 



A break in deposition. 

 1. Thebes sandstone: Brown or chocolate colored, rather fine- 

 grained sandstone, which weathers into thin layers 40 



In the above section the members 4 to 10, inclusive, constitute the 

 Edgewood beds, as that formation is seen at its best exposure in south- 

 west Illinois. At this place the Girardeau limestone was almost entirely 

 cut out by erosion prior to the deposition of the Edgewood strata. A 

 thickness of 13 or more feet of the Girardeau limestone outcrops in the 

 river bluff a few rods north of this place, and masses of this rock, 6 or 8 

 feet in thickness, are also exposed along the river bank a few rods south 

 of the place where the section was made. The conglomerate at the base 

 of the Edgewood, number 4 in the section, is largely composed of frag- 

 ments of Girardeau limeston. 



Another instructive exposure of the Edgewood strata in this vicinity is 

 in an abandoned quarry one-fourth mile southeast of the village of Gale, 



