CHAPTER LXXXIV. 



REPORT ON THE GEOLOGY OF FRANKLIN COUNTY. 



BY EDWARD ORTON. 



SITUATION AND TOPOGRAPHY. 



Franklin county is bounded on the north by Delaware county, on the 

 east by Licking; and Fairfield, on the south by Pickaway, and on the 

 west by Madison. Union county touches it also on one corner, furnish- 

 ing a very small portion of the northern and western boundary. Its 

 position in the State is very nearly central. A nearer approximation to 

 an exactly central location, could have been secured by combining por- 

 tions of Delaware and Franklin counties in one county. 



Its topography is very much more varied than that of any of the coun- 

 ties that lie along the same parallel to the west of it, the valleys of the 

 Scioto and its tributaries constituting the chief features. This first 

 named valley divides the county into two main divisions, the eastern 

 division having the la,rger area. Its course, from the northern border to 

 the center of the county, is south-easterly ; from this last named point 

 to the line of Pickaway county, its direction is very nearly south. Sev- 

 eral of the principal tributaries of the Scioto do not enter it within the 

 limits of the county, but they run in north and south valleys approx- 

 imately parallel to the main valley, until they pass the southern 

 boundary. 



The north and south direction of the tributary valleys, as well as of 

 the main valley, is a characteristic of the county, especially of the 

 northern half. It is well shown by a section taken from west to east 

 along the southern line of Sharon township. Beginning on the west 

 side of the county, with the well-marked valley of Big Darby Creek, we 

 find a dividing ridge, about eight miles in breadth, from which we de- 

 scend into the Scioto Valley. A second stretch of table land, about five 

 miles wide, carries us to the Olentangy Valley. The intervening high 

 ground between this and Alum Creek Valley, is not far from seven miles 

 in width, while not more than three miles separate the Alum Creek 

 Valley from the Big Walnut Valley. About four miles intervene 



