^^^ GEOLOGY OF OHIO. 



In the eastern, and especially in the north-eastern and south-eastern 

 parts, the surfaee is hilly and broken, and the erosion of the Coal Meas- 

 ure rocks has left a succession of terrace-like benches, which characterize 

 the hilly regions of the coal-fields of the State. 



In protected places the drift clay covering still remains in these hilly 

 regions, and sometimes caps the highest hills. East of Mt. Eaton, an ex- 

 cavation for coal discloses 



Yellow drift clay 12 feet. 



Bhie " " 6 " 



Both members containing striated pebbles of the blue limestone, which 

 is in bed on this horizon, and rounded pebbles of granitic rocks. The 

 surface deposits in the central and western parts of the county are simi- 

 lar to those described in the preceding counties. Between the streams 

 an undulating and billowy surface of yellow clay, with blue clay below, 

 may be seen resting, sometimes directly upon the bed-rock, sometimes 

 with a bed of gravel interposed. On the margins of the streams and old 

 pre-glacial channels are sand and gravel ridges, and in the valleys allu- 

 vium, resting upon beds of lacustrine clay, gravel, or bowlder clay, some- 

 times over one hundred feet in depth. 



GEOLOGICAL STRUCTUBE. 



A small portion of the northern parts of Canaan and Milton townships, 

 the greater part of Chippewa and Baughman, all of Sugar Creek and 

 Paint, the greater part of East Union and Salt Creek, and a small por- 

 tion of Green, Franklin, and Clinton townships are covered by the coal 

 formation. All the rest of the county is Waverly, as indicated by the 

 shading upon the map. This western margin of the coal rocks is by no- 

 means coincident with the western margin of the coal, as the sandstone 

 belonging above the Upper Coal is in places found resting directly upon 

 the Waverly, without coal, coal shale, or fire-clay to mark its horizon. 

 The brown shading indicates, as accurately as could be determined, 

 the territory covered by rocks belonging above the Sub carboniferous 

 Conglomerate, which is h^re not continuous, and is colored red. Along 

 parts of this western margin heavy beds of Drift mark the geological 

 structure, and the line is located approximately, as the topography and 

 the nearest outcrops of the rocks indicate its position. 



A section from Mt. Eaton to the bottom of the valley at Fredericks- 

 burgh would expose all the rock strata of the county, froni Coal No. 7, at 

 the top, to the Waverly. 



