CHAPTER LXXVI. 



EEPOKT OF THE GEOLOGY OF MIAMI COUNTY, 



i The undulating surface of Miami county, is eiiaracteristic of, and de- 

 pendent upon, the underlying geological formations. We find a bed of 

 loose m'aterial of greater or less thickness overlying a not very unevers 

 rock bed beneath. This condition determines the gentle siopea which 

 prevail throughout this section of the State. The blue litijestone 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 rolling slopes 

 BO characteristic of south-western Ohio, 



What abrupt unevenness of surface exist, are partly covered up hy the 

 loose material, 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 ail, 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 is 

 required of me in this place. 



