620 GEOLOGY OE OHIO. 



the beds at this point. There are no fossils found in either. At Piketon, 

 where the junction between the two groups of rocks is shown with all 

 possible distinctness, it appears, from the occurrence of thin beds of 

 black shale in the lowermost twenty feet of the Waverly beds, that the 

 formation of a shale entirely like the Huron in character was resumed 

 more than once in the early days of the deposition of the Waverly group ; 

 but these returns of previous conditions in the seas were of short dura- 

 tion, and were soon lost altogether. 



A few thin courses of solid stone of remarkable evenness and of very 

 fine grain occur almost every where at ten to twenty feet above the base. 

 They can be seen to excellent advantage in the river bank, on the land 

 of Mr. John Gregg, two miles above Piketon. Analysis shows that these 

 hard and ringing layers have a large enough amount of lime and mag- 

 nesia in their composition to put them in the list of impure limestones. 

 This is the only known occurrence of calcareous layers in the whole Wa- 

 verly series until, at least, its very summit is reached in the regions to 

 the eastward of Pike county. The composition of two specimens is 

 shown in the appended analyses made by Prof. Wormley, Chemist of the 

 Survey. The sample marked No. 1 was obtained from Wolf Run, one 

 mile east of Buchanan. No. 2 comes from. the neighborhood of Mineral 

 Springs, on the north line of Adams county : 



No. 1. No. 2. 



Silicious matter 71.40 58.80 



Alumina and iron 2.40 5.80 



Carbonate of lime 24.40 27.00 



Carbonate of magnesia 1.05 8.62 



99.25 100.22 



The Waverly shales were evidently formed under very different condi- 

 tions from those to which the origin of the overlying group must be re- 

 ferred. The latter never show ripple-marks, sun-cracks, or other indica- 

 tions of having been formed in shallow water, while the Waverly shales 

 are conspicuously marked in this way. The surfaces of successive layers, 

 for many feet in thickness, are often covered with ripple-marks, all of 

 them holding the general direction of north 53° west, or south 53° east.* 



Exposures of these beds are of common occurrence through all of the 

 western half of the county. On Wolf Run, a small branch of Peepee 



* The Survey is indebted to H. W. Overman, Esq., County Surveyor, for a very care- 

 ful series of measurements. Of twenty-four observations, fourteen were found south 

 53° east, as given above. Four points showed south 65° east ; one south 46° east ; one 

 south 57° east. The points that showed south 65° east overlie the other exposures, 

 and probably indicate a real change of direction in the wave action. 



