CHAPTER LXXVI. 
REPORT OF THE GEOLOGY OF MIAMI COUNTY. 
The undulating surface of Miami county, is characteristic of, and de- 
pendent upon, the underlying geological formations. We find a bed of 
loose material of greater or less thickness overlying a not very uneven 
rock bed beneath. This condition determines the gentle slopes which 
prevail throughout this section of the State. The blue limestone in the 
southern part of the county, on the two principal water-courses, is a thin- 
bedded stone, inter-stratified with thicker courses of blue marl or shale, 
which do not resist the action of atmospheric agencies in a sufficient de- 
gree to form precipitous bluffs, but wear down into those ee slopes 
so characteristic of south-western Ohio. 
What abrupt unevenness of surface exist, are partly covered up by the 
loose rhaterial, composed of gravel, sand, and clay, which commonly re- 
ceive the name of Drift, spread over the surface. If this Drift were not 
present, we should be able to trace the line of outcrop of the cliff forma- 
tion wherever it occurs throughout the county. There would be a chain 
connecting the cliffs near Charlestown with those two miles east of 
Tippecanoe, at Col. Woodward’s, and onward, marking the course of all 
the tributaries of the Miami, and showing the course of this river, limit- 
ing the valley, to the point where the Miami enters the county on the 
north. In most instances the beds of the water-courses would be greatly 
deepened, and there would be rapids or even precipitous falls in some 
places in most, if not all, of them. The same remark applies to the 
Stillwater, which would be lined by a series of cliffs throughout its entire 
- course in the county. But the Drift now smooth, in a great degree, the 
unevenness of the surface and the transitions from one geological forma- 
tion to another, are only by gentle undulations of surface, instead of abrupt 
cliffs. The origin of this Drift material is discussed at considerable 
length in other portions of these reports, and no further allusion to it ig 
required of me in this place. 
