192 J, Hall on Carboniferous Limestones of Mississippi Valley. 
ary limestone of Dr. Owen is succeeded by sandstones and shales 
of the coal measures, which is the true order at the mouth of 
the Desmoines and other places, but not universally true. In 
the section of Prof. Swallow, the St. Louis limestone (Concre- 
tionary limestone of Owen) is shown to be succeeded by a bro 
or ferruginous sandstone, F, of section of Missouri report, and 
upon this rests the lower coal measures. This order is likewise 
true of some parts of Missouri and of Illinois, but it is not every- 
where true in these states. 
The ferruginous sandstone is in turn succeeded by an exten- 
sive and important limestone formation, consisting of beds o 
limestone of greater or less thickness alternating with thin seams 
of marl or shale, and in some parts heavy bedded limestone of 
considerable thickness, without shaly partings or with very thin 
ones. The group embraces likewise one or more heavy sand- 
ten and amass of green shale or marl more than fifty 
thick. ; 
formation constitutes the limestones of Kaskaskia and 
: : : y 
the abundance of its Pentremites. It has evidently been always 
confounded with the lower Archimedes or Keokuk limestone, 
of the lower ones. The strati p Srene HeC 
The following section illustrates the preceding statements Te 
gore e order of superposition among the different cnecibert 
% estone series. 
