CHAPTER LXXXVII. 
REPORT ON THE GEOLOGY OF MAHONING COUNTY. 
BY J. S. NEWBERRY. 
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 picturesque, while at the same time it is 
well adapted to agricultural purposes, and is now very generally ina 
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 
shales of the Waverly and Erie in Trumbull and Ashtabula, is clay. On 
