344 GEOLOGY OF OHIO. 



The dip is very slight, but to the north. In regular order, and a little 

 further north, the Onondaga beds of the Corniferous group appear. Next 

 the Corniferous proper appears at the mouth of the JFlatrock, with dip 

 north-east. About three-quarters of a mile still further occurs the out- 

 crop which holds the abundant Hamilton fossils, there the dip being 

 in the same direction and to the same amount. This is at the mouth 

 of the Little Flatrock. A half mile still further north is Mr. Mead's 

 quarry, in the blue limestone of Delaware, the dip being the same. A 

 few rods still further north is Mr. Columbia's quarry, in the beds of the 

 same, or nearly the same, horizon. About three-quarters of a mile still 

 further north the blue limestone is again quarried, in section 17, Defi- 

 ance, Defiance county, where the dip is still north or north-east. About 

 a mile and a half still further the Tully limestone comes into view, and 

 is wrought by Mr. Dilz for lime. A mile still further the black slate 

 appears. Throughout the whole of this distance there is no return of 

 the strata by an exceptional dip. The beds occur in exactly that order 

 they should if laid regularly down like the shingles on a roof. The 

 inference is inevitable that the lowest layers occur in outcrop furthest 

 south. Now, as there is no blue limestone exposed to the south of the 

 mouth of the Little Flatrock, but since there is, on the other hand, 

 abundant exposure to the north, the dip being observed constantly to 

 the north, the rock at the Little Flatrock containing the Hamilton 

 fossils mentioned must lie below the rest of the blue limestone observed, 

 and very near the bottom of that formation. There can be no other 

 evidence except that of actual, observed superposition. The writer did 

 not give strict attention to the subject of the downward limitation of 

 well-known Hamilton fossils in the survey of any other county, having 

 regarded the uniformity of lithological characters sufficient to establish 

 the essential unity of the whole of the blue limestone, and never having 

 noticed a lack of corresponding uniformity of palasontological charac- 

 ters. Those palasontological characters were sufficient to indicate the 

 Hamilton age, and the perfect parallelism of the blue limestone with 

 the Hamilton limestone of the adjoining State of Michigan. 



No. 5 is that which is seen in the Auglaize River, near the mouth of 

 the Flatrock. It is much different from the blue limestone in lithologi- 

 cal characters. It is not so hard, nor so dark-colored. The beds are 

 generally of about the same thickness as those of the blue limestone, but 

 much less uniform. They are apt to taper toward the right or left, and 

 appear as lenticular pieces. Their upper surfaces are also roughened 

 by prominent corallites. It is much freer from argillaceous matter than 

 the blue, and makes a whiter quicklime. It is sometimes crinoidal. and 



