The MaquoTceta Shales. — James. 349 
Returning now to Richmond, and taking a line toward the 
northwest in the direction of Savannah, Illinois, and the Lit- 
tle Maquoketa river, Iowa, we have records of 14 stations in 
Indiana. These are arranged in the preceding table. 
In this table we find a different series of results. The alti- 
tudes of the rock level do not decrease uniformally, though 
there is such a decrease in general terms. The altitude of the 
top of the Cincinnati group shows an almost uniform decrease. 
The thickness of the rocks diminishea from 900 to 305 feet in 
a distance of about sixty miles, or ten feet to 'the mile. Then 
it increases to 600 feet in eighteen miles, and subsequently di- 
minishes almost regularly for forty miles further, for at Flora 
it is only 306 feet in thickness. 
We are unfortimately without definite information concern- 
ing the underground geology in the two Indiana counties near 
the western border. The surface of these is covered with drift, 
but in Jasper county, near Rensselaer, the Niagara is exposed 
for about eight feet, and a well was sunk to a depth of over 800 
feet into limestone. Part of this is Niagara, part Cincinnati 
and probably part Trenton. 
Mr. Leverett in discussing the features of his table remarks 
that the Cincinnati axis extends in a southeast and northwest 
direction, and he demonstrates it by figures relating to the 
Trenton. We believe the same is shown by the figures given 
in the above table. It is apparent, at all events, that at Koko- 
mo we are on the slope of the axis, for in the course of twen- 
ty miles the altitude of the top of the group above tide, dimin- 
ishes over 300 feet, or about 15 feet to the mile. 
Mr. Leverett refers also to the probable existence of an east 
and west axis of upheaval as extending from Carroll county 
westward to Monon and Kentland. At these two places are 
found outcrops of Niagara limestone, that at the latter place 
apparently being an isolated fragment in the midst of a De- 
vonian area, and forming an island, as it were, half-way be. 
tween the Niagara and Sub-Carboniferous formations. 
From the reports of the Geological Survey of Illinois we 
glean a number of interesting facts relative to the rocks of the 
Cincinnati group in that state. The line we have been tracing 
enters and crosses the nortlioast corner of Iro(}Uois county. In 
the western half of the county the Coq\ Measures come to the sur- 
face. Near its centre a seam of coal eight feet thick, was reported 
