CHAPTER XLVII. 



REPORT ON THE GEOLOGY OF MERCER COUNTY. 



BY N. H. WINCHELL. 



SITUATION AND AREA. 



Mercer county lies on the Indiana State line. Its form is that of a 

 regular parallelogram, twenty-six miles in length north and south, and 

 eighteen in width, embracing thirteen towns of thirty-six square miles 

 each. It is bounded north by Van Wert county, east by Auglaize, and 

 south by Darke. 



NATURAL DRAINAGE. 



The natural slope of the whole county is toward the north, and the 

 small streams which take their rise between the ridges run uniformly in 

 that direction. Encountering the ridges, they unite to form one main 

 stream along the upper or outer side of each ridge, which then flows di- 

 agonally across the general slope toward the west or north-west, follow- 

 ing the direction of these barriers. Thus the small streams which form 

 the Wabash rise in Darke county or the extreme southern part of Mercer, 

 and run north till they meet the St. John's Ridge, when they are diverted 

 westward. Before the Wabash leaves the county it crosses this barrier 

 near Fort Recovery, owing, probably, to the very gravelly character and 

 the rolling surface of the Drift prevailing in that section, and then fol- 

 lows the natural, direct descent till it meets the Wabash Ridge. This it 

 is not able to pass, but follows it into Indiana. It finally is carried in 

 this way over the great watershed; or rather, the great watershed verges 

 so far north as to appear on, the other side of this ridge, allowing the 

 Wabash to join the Ohio toward the south. A number of other streams 

 of Mercer county are in the same way diverted westward by the Wabash 

 Ridge. On the north of this ridge the streams have a northerly direc- 

 tion to their union with the St. Mary's, when, with it, they are carried 

 along the southern side of the St. Mary's Ridge till, meeting the St. Jo- 

 seph at Fort Wayne, Indiana, their united waters have succeeded in 

 passing the ridge. 



