DEL A WAKE COUNTY. 273 



with its tributaries, constitutes an important system of drainage. The 

 whole limestone district, which embraces all that part of the county 

 west of the Olentangy River, except that underlain by the Waterlime, 

 is moderately undulating, the surface being worn by erosion into shal- 

 low depressions, which, near their junction with larger streams, be- 

 come ravines bounded by steep bluffs. The district of the Waterlime is 

 flat, especially in the townships of Radnor, Thompson, and Scioto. The 

 deeply eroded valleys of the Scioto and Olentangy constitute the most 

 marked topographical features of the county. In the southern part of 

 the county these valleys are deeply cut in the underlying rock. The 

 divide between them at a point west of Powell is one hundred and 

 twenty- five feet above the Scioto. That interval is made up mostly of 

 the beds of the underlying limestone, the Drift not having an average 

 thickness of over twenty-five feet. The descent to the Olentangy is 

 usually very gentle, occupying sometimes. the space of a mile or more on 

 either side ; while the valley of the Scioto is narrower, and its banks 

 more frequently rocky and precipitous. The valley of the Olentangy is 

 excavated for the most part in the black slate or the underlying shale, 

 but that of the Scioto is cut in solid limestone strata. This fact may 

 account for the greater breadth of the former. 



In the north-western part of the county the valley of the Scioto is 

 strikingly different from the southern part. It has here the features 

 that the same valley presents in Marion and Hardin counties. The 

 bluffs are never rocky. The general level of the country is but little 

 above the level of the water in the river. The stream has not yet cut 

 its channel throughout this part of its course through the Drift, and in 

 traveling along its valley one is forcibly reminded of the strong resem- 

 blance of the face of the country to the Black Swamp region of north- 

 western Ohio. It is a natural and reasonable inference that this portion 

 of the country has had a very different superficial history from the south- 

 ern and eastern parts, and one that allies it more to the Lake Erie val- 

 ley than to the Ohio shope. These Black Swamp features prevail in the 

 townships of Radnor and Thompson, and in the north-western part of 

 Scioto. 



Railroad Elevations. 



Above Lake Erie. Above the Ocean. 



Morrow county line (C. C. C. & I. E. R.) 



Ashley (0. 0. C. & I. R. R.) 



Eden " 



Delaware " 



Berlin " 



Lewis Center " 



18 



