A CONTRIBUTION TO MADISON COUNTY GEOLOGY. 
BY F. A. BKOWN. 
There is given below a typical or general section of the Missourian 
formation in Madison county, as given by Tilton and Bain.* It is mainly 
to the rocks of this stage that reference will be made in the present 
paper. 
NO. SECTION. FT. INS 
20. Limesone, yellow, earthty, thin layers, fusilina, aulopora and 
Froductus 4 
19. Shale, drab to yellowish 1 
18. Alternating calcarean and shaly bands yellowish with Derbya- 
crassa, — Froductus and spirifer planoconvexa 3 
17. Dark shale 1 2 
16. Ledge of compact limestone '. 1 2 
15. Dark blue shale, many crushed Froductus 6 
14. Black, very carbonaceous shale 1 
13. Shale, argillaceous above, sandy below 4 6 
12. Limestone, coarse, divided by shaly partings 3 
17. Shale, dark, in part very carbonaceous with band crowded 
with Chonetes. In places, the Chonetes are cemented into a 
band of limestone 8 
10. Blue limestone, very fossiliferous, three bands separated by shale 3 
9. Shale, dark above, lighter below 2 
8. Marly, yellowish shale 2 
7. Yellowish soft limestone becoming harder below 5 
6. Thin layers of limestone shaly partings 12 
5. Black slate and shale 3 
4. Yellowish, earthly, calcareous beds 4 
3. Limestone, with thin alternating bands of shale 12 
2. Black shale 3 
1. Band of limestone 6 
To continue this section to the base of the Missourian we have ; 
5. Sandy shale 15 
4. Limestone weathering into nodular fragments 5 
3. Shale parting 3 
2. Limestone, similar to number 4 4 
1. Shale, blue to buff '. 2 
According to the authors of the report on the geology of Madison 
county, the foregoing constitutes a typical section from the top of the Des 
Moines stage to and including the base of the Fusilina limestone, which 
is number 20 of the section: Nos. 6, 7 and 8 of the above are the Win- 
terset limestone. The following section is exposed at the quarries of the 
stone company at the town of East Peru. 
10. Yelelowish, marly shale, with Derbya and Phillipsia .... 3 or more 
9. Limestone, yellow earthy — Allorisma 2 
8. Shale 1 
7. Limestone, yellowish somewhat sandy 4 
6. Shale, with numerous Choretes 10 
5. Limestone, bluish with Conchoidal fracture 10 
4. Shale parting 1 
3. Limestone, heavy bedded 4 1 
2. Shale, with Chonetes and Rhombopora 1 
1. Limestone, bedded from 4 to 12-in 6 
It seems probable, that number 10 of the quarry section at Peru cor- 
responds with No. 8 of the general section, that Nos. 7, 8 and 9 are 
the equivalent of No. 7 of the general section, and Nos. 1, 2, 3, 4, 5 and 
6 of the Peru quarry section can be correlated with No. 6 of the general 
section given above. 
*Geolog:y of Madison county, in VII Ann. Report la Qeol. Surv. 
(203) 
