264 GEOLOGY OF OHIO. 



out Peru township, and especially in the banks of Alum Creek, make it 

 evident that the underlying Erie shale, if it exists at all, must be re- 

 duced to a few feet in thickness. The absence, then, of the Erie shale, 

 or its great attenuation, makes it uncertain whether the above exposure 

 may not belong to the Huron. It bears a resemblance to some portions 

 of the Huron. In the absence of fossils, it will be necessary to leave its 

 designation conjectural. 



The Erie Shale. — The existence of this shale in Morrow county is 

 altogether hypothetical. The most southern point at which it has been 

 observed is in Polk township, in Crawford county. It is not known to 

 exist in Delaware county, which lies next south of Morrow, but it may 

 have the thickness there of a few feet. This horizon, owing to its shaly 

 character, is generally deeply buried under the Drift. On the accompa- 

 nying map this shale is represented as running out, but the evidence to 

 that effect is not conclusive. 



Huron Shale. — This shale underlies the western tier of townships,'its 

 eastern limit leaving the county near the south-west corner of Benning- 

 ton township and the north-west corner of Washington township. It 

 is well exposed at a number of places, especially along the valley of the 

 East Branch of the Olentangy, in Westfield and Cardington townships, 

 and along Alum Creek, in Peru township. The exposure at Cardington 

 amounts to about twenty feet. It is here in very thin beds (J? to \ of an 

 inch), and parts, under the weather, into small chips. When wet it has 

 no unctuous feel, but keeps its color and texture. It is rather firm, and 

 of a black color. It contains no concretions, or hard masses. An in- 

 crustation of alum forms on the exposed edges of the beds, but very little 

 pyrites can be seen. The beds have a slight dip east. 



The black slate, or Huron shale, is exposed in the banks of the creek 

 on lot 13, land of Annis Oliver, and at other points below. At Benedict's 

 mill, lot 16, twenty feet may be seen. It is here, also, of a very homo- 

 geneous character, like that at Cardington. 



This exposure is approximately forty feet below that at South Woodbury. 



At West Liberty the following section, in d ^ -mding order, may be seen : 



No. 1. Hard-pan Drift __ 20 ft 



" 2. Thinslate "' 6 «' 



" 3. Blue, silioious limestone, like that at South Woodbury. In 



one bed 4 j n 



" 4. Thin, homogeneous slate 30 " 



Total 56 ft. 4 in. 



Along Alum Creek, about half a mile north of the county line, the 

 Huron shale is well exposed. Indeed, there is nearly a constant exposure 

 of the black slate along that creek south from South Woodbury to the 



