7s The American Geologist. August, 1893 
stone. The Second Magnesias Limestone on which it rests is 
the rock seen all along the railroad from Washington to Jef- 
ferson city, and at Jefferson it reaches from the base to the 
summit of the hill. The lower beds are thick and densely 
crystalline and often cellular. Higher up are argillo-mag- 
nesian limestones, locally termed Cotton rock, and often sep- 
arated by buff shales inclosing chert concretions, with some- 
times a thin bed of white sandstone. Thin layers of Oolitic 
chert are occasionally found. Lingula, Orthis Pleurotomaria, 
Straparollus, Ophileta, Murchisonia and a trilobite have been 
found, and the limestones often seem to be made up of fu- 
coids. Many of the limestones also emit a fetid odor when 
struck. 
The section at Pacific shows : 
1 — Trenton limestone with Black river beds at the lower part. 
2 — First Magnesian limestone with Cythere. 
3—100 feet of exposed First sandstone. 
Just east of Pacific the sandstone dips beneath the horizon. 
In St. Charles county, just below Augusta, we have : 
1 — Trenton and Black river limestone. 
2 — First Magnesian limestone. 
3—133 feet of Saccharoidal sandstone. 
A little to the east the sandstone dips beneath the horizon. 
One mile west of Augusta the First sandstone rests upon the 
Second Magnesian limestone, and it is found in that position 
westwardly in Warren, Montgomery and Callaway, but be- 
comes gradually thinnerto the west, and in Callaway it often 
occurs as a pocket overlying older rocks. At West Point, 111., 
the succession is the same as that observed at Pacific and at 
Augusta. At Westpoint the sandstone occupies the base of 
the bluffs for one mile, and shows 75 feet thickness. It is 
also here soft and white and it has been referred by Prof. 
Worthen to the age of the St. Peter sandstone. It is overlain 
here by 75 feet of First Magnesian limestone 'with Trenton 
limestone above, containing well known Lower Silurian fos- 
sils. 
At Jones Siding, Kails county, the sandstone is barely ex- 
posed at the foot of the hill, but the overlying limestones 
exactly resemble those seen at Westpoint, Illinois, nearly 100 
miles distant. In the insane asylum well, St. Louis, the First 
sandstone (St.Peter) was reached at about 1,400 feet, and 
