254 GEOLOGY OF OHIO. 



are unmistakable evidences of a previous erosion of the rock surface, but 

 in the western part of the county no such indications have been seen. 

 Besides occasional irregularities in the surface of the bedded rocks, the 

 manner of the deposition of the Drift was such as to leave very noticeable 

 differences in its condition and thickness in different parts of the county. 

 In the sandstone region, and especially where the Berea grit forms a line 

 of junction with the underlying shale, the Drift is coarse and stony, and 

 the surface is broken. Frequent springs of ferriferous water issue from 

 the hillsides, which seem to be very gravelly. The channels of the 

 streams are deeply cut into the bed rock — plainly beyond the power of 

 the present volume of water — and the valleys are marked by large bowl- 

 ders. Such bowlders are found in the valleys in all parts of the county, 

 but are much more noticeable in the sandstone district. Near South 

 Woodbury, in the creek bottoms (lot 10), is a bowlder of fine-grained 

 syenite, the extreme dimensions of which are nine feet by seven and a 

 half feet, showing four and a half feet above the ground. In this bowl- 

 der hornblende predominates, and the feldspar is flesh-colored, quartz 

 being scarce, giving a rather dark color to the whole. In the western 

 part of the county, however, where the surface is underlain by shale or 

 by the black slate, the Drift is more evenly spread, and the country is 

 flat. The streams have (in very much the same manner, though not to 

 the same extent) cut their channels into the bed rock, but they are fewer 

 in number, and have a less average descent to the mile. The water of 

 wells and natural springs is apt to be sulphurous, and bubbles and jets of 

 gas are very often met with. In some marshy places an inflammable 

 gas rises spontaneously, though this is not known to be the same as that 

 which rises from the shale below the Drift. The surface is clayey, and 

 the soil heeds artificial drainage. 



The following observations for altitude, by aneroid barometer, are re- 

 ferred to the level of Lake Erie through Mt. Gilead Station, the height 

 of which is given at 466 feet by the Cleveland, Columbus, and Cincin- 

 nati Railroad 



Above Above 



Lake Erie. the Ocean. 



Mt. Gilead Station 466 feet. 1031 feet. 



Sill of National House, "Mt. Gi 1 . ^d 516 " 1081 " 



Creek at the mill, Mt. Gilead 391 " 956 " 



Creek at south bridge, Jit. G'iead 356? " 921? " 



Summit of ridge 1 % miles north of Franklin Center, 



section 7, Franklin 625 " 1190 " 



Summit of ridge, Franklin Center 599 " H64 " 



Chesterville, A ain street 320 " 885 " 



Chesterville, bed of creek 286 " 851 " 



Bloomfield Cemetery, N. W. \ section 17 576 " 1141 " 



