34 The Ainerlcan Geologist. juiy. i89i 
is suitable for building. Fossils are not abundant. Those found 
area Xm^»/a (like L. prima Ilall) an OphihUa^ and Pleurotomaria. 
At the base of the hill at Hermann, a trilobite (probabl}- C0710- 
cepJiaUtcs), an Orthis, &c. , were obtained. 
The Second sandstone occupies the tops of the hills in Madison, 
"Washington, Rej-nolds, and some other counties, and is apparently 
replaced b^' certain chert beds in those counties. This sandstone 
is coarser than the First sandstone, and is often slightly colored 
with iron, and is often a firm, solid rock, useful for building pur- 
poses. The Third Magnesian limestone occupies the base of 
nearly all the hills of southern ]Missouri, sometimes reaching to 
the hill tops. It occurs chief!}' in thick beds of coarse, gra}* dolo- 
mites, or finer textured flesh-colored la3-ers, the latter sometimes 
as much as 20 feet thick between the bedding planes. The coarse 
gray dolomites often disintegate and weather into rough surfaces, 
and at the lead mines decompose into dolomitic sand. 
The Third sandstone was recognized by Prof. Swallow, on the 
Osage and Niaugua rivers, in Camden and Dallas counties. 
A part of this series may be referred to Prof. Dana's Canadian 
period. 
The First Magnesian limestone lying below the Trenton group, 
may l)e Lower Silurian, and some have considered it to be 
of the age of the Chazy; in the absence of fossils it is not eas}- to 
assign it to its proper place. The series below, including to the 
base of Second sandstone, and probably part of the Third Mag- 
nesian limestone, may be considered of equal age with the Calcif- 
erous of the New York system. The Lower part of the Third 
IMagnesian limestone ma}' probabh' be of the age of the Potsdam, 
and the other strata below seem certainl}' to be of Potsdam age. 
The Second Magnesian limestone and the other series below to 
the Archaean seem to correspond with the description and position 
of l)eds referred to the Lipper Cambrian by Mr. C. D. Walcott. 
So, whatever may be the true geological position of this series of 
rocks, they belong to different periods of geologic time. I there- 
fore, for this reason and from the similarit}' of the composition of 
the rocks, think best to place them in one series, and call that great 
series 
"The Ozahk Sekies" 
Distributed as follows: 
First Magnesian limestone. 
First or Saccharoidal sandstone — St. Peter's sandstone. 
Second Magnesian limestone. 
