J. Hall on Carboniferous Limestones of Mississippi Valley. 189 
2 [{. Lower coal measures, - - — - - 140 fee 
52 | F. Ferruginous sandstone, - — - i ib 
2 4 G. St. Louis limestone, - - - 250 « 
£2 | H. Archimedes limestone, - - - = 200° = 
© (1 Encrinal limestone, - -~— - - 500 “ 
#(J. Chouteau limestone, -  - - - 70 * 
2: K. Vermicular sandstones and shales, - 7. 
6“ (L. Lithographic limestone, - - - - 60 * 
Under each of these divisions are given numerous localities 
where the rock is well developed. 
In descending the Mississi pi river, we come upon the lowest 
and most northerly outcrop of these limestones at Burlington, 
Towa. At this locality we have the following section, in the de- 
Scending order. 
Encrinal limestone. 
2. Oolitic limestone, fossiliferous. 
8. Compact arenaceous limestone. 
4. Fine grained argillaceous sandstone or grit stone, with casts 
of Spirifer, Chonetes, Productus, Bellerophon, Orthoceras, ete. 
5. Green shale. 
The entire thickness of 2, 3, 4, and 5, is about 70 to 80 feet; 
the base of the green shale however has not been observed. 
tocks of that group in New York and elsewhere, and have been 
carefully traced throughout the intermediate space. It is luite 
probable that, in strict aque the green shale of Burling- 
lies between well marked Hamilton : 
And it is likew; that the Lithographic limestone of 
mallow vil apna nabs closely allied to the Hamilton 
\ 
