CHAPTER LXXXVII. 



REPORT ON THE GEOLOGY OP MAHONING COUNTY. 



BY J. S. NBWBBRKY. 



SURFACE FEATURES. 



Viewed as a whole, the surface of Mahoning county may be regarded 

 as an undulating plain, sloping gently to the north, its southern line 

 running on or near the divide between the waters of the Mahoning on 

 the north and the Little Beaver on the south, and having an altitude of 

 from three to five hundred feet above the valleys of the north border. 

 Topographically, the county forms a portion of the highland of the 

 southern rim of the lake basin, but since this rim is cut through by the 

 deep gorge of the Mahoning, the drainage, though locally northward, is 

 all carried through that channel into the Ohio. But little of the surface 

 is even locally level, but consists of an alternation of broad valleys of 

 excavation, separated by rounded hills and tablelands, with gentle 

 slopes. It is all varied and picturasque, while at the same time it is 

 well adapted to agricultural purposes, and is now very generally in a 

 high state of cultivation. The soil is in some places derived from the 

 •decomposition of the underlying rocks ; but it, for the most part, rests 

 upon a sheet of Drift material, for the county lies within the Drift area, 

 though reaching its margin on the south. The general slope of the sur- 

 face, and part of the local erosion, seem to have been produced by the 

 southern extension of a tongue or lobe of the great glacier, which, moving 

 from the north, excavated the low country that lies between the high- 

 lands of Geauga and Portage on the west, and those of Pennsylvania on 

 the east. By this agent the northern outcrops of the rocks which under- 

 lie the country have been ground away, and a large amount of material 

 transported southward from its place of origin. As the eroded rocks 

 were largely sandstone and Conglomerate, much of the transported ma- 

 terial is gravel and sand; while a part, produced by the erosion of the 

 fihales of the Waverly and Erie in Trumbull and Ashtabula, is clay. On 



