CHAPTER XLVITI. 
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 
elghteen 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. HWncountering 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. 
