33 
THE OZARK SERIES. 
By G. C. Bkoadhead, Columbia, Mo. 
In the Geologist for January and September 1889, the Ozark 
plateau was discussed by myself as to its elevation and extent. 
In the Missouri geological report, 1855, Prof. CI. C. Swallow 
published a vertical section of palaeozoic rocks, which has suf- 
fered but few corrections. As corrected, it is about as follows: 
Upper Carboniferous 2000 feet 
Lower Carboniferous to base of Burlington 1145 " 
Chouteau group 205 ' ' 
Devonian 125 " 
Upper Silurian 175 " 
Hudson River group ■ • • ■ 165 " 
Tienton and Black River limestones 360 " 
MAGNESIAN LIMESTONE SERIES. 
First Magnesian limestone 190 " 
First or Saccharoidal sandstone 125 " 
Second Magnesian limestone 230 " 
Second sandstone 70 " 
Third Magnesian limestone 350 " 
Third sandstone 50 " 
Fourth Magnesian limestone 300 " 
This series of magnesian limestones is known in Missouri by its 
numbers; the "First" is rarely found in central-southern Missouri, 
excepting on the most elevated points, but it is better developed 
in the counties bordering the Missouri river, occurring as a gray 
or buff or drab limestone, sometimes oolitic as near Horiile in Jef- 
ferson county, or abounding in Cythere suhhvois, as at Pacific, in 
Franklin county. The First, or Saccharoidal sandstone reaches 
its greatest thickness near Augusta, St. Charles countj^, where it 
is 133 feet thick. 'A corresponding thickness was recorded in the 
boring at the Insane Asylum, St. Louis. Its upper part is white 
and pure silica, its lower part often colored brown. It is the 
equivalent of the St. Peter's sandstone. The only evidence of 
organic remains found in it is a large Orthoceras, about 8 inches in 
diameter. 
This sandstone is valuable as a material for glass-making, and 
the glass-works at Crj'stal C ity, in Jefferson county, are located at a 
favorable outcrop. The Second Magnesian limestone is well ex- 
posed at .Jefferson City, and includes all the strata in sight at that 
cityr The lower beds are thick and cellular, the small cells filled 
with a white powder, or else empty. Above these there is a good 
deal of chert occurring mostly in a concretionary form, together 
with some shale, and earthy drab-colored magnesian limestone 
beds, locally called "cotton rock. " But a small percent, of this 
3 
