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 Flatrock, with dip 
north-east. About three-quarters of a mile still further occurs the out- 
erop 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 paleontological charac- 
ters. Those paleontological 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 
