DEFIANCE COUNTY. 425 
GEOLOGICAL STRUCTURE. 
The rocks of the county embrace the limestones of the Devonian and 
the overlying shales. The highest observed rock is the black slate, but 
it is very probable that higher formations of shale, corresponding to 
_ those above the black slate on the eastern side of the anticlinal, also 
succeed in ascending order in Defiance county, occupying a surface area 
comprising most of the northern tier of towns. The general dip 1s to- 
ward the north. The lower portion of the great Corniferous group of Dr. 
Newberry forms the surface rock of the south-eastern half of Highland 
township. The upper portion of the same, represented by the blue stripe 
on the map, succeeds it on the north, its northern boundary crossing the 
Auglaize River in section 8, Defiance township. The greater portion of 
the Hamilton fossils found in this county pertains to the lower part of 
this limestone, but they are found also throughout its whole thickness. 
It is hence styled Hamilton on the accompanying map, that shale which 
Dr. N. regards as Hamilton in the central portion of the State not hav- 
ing been discovered in Defiance county. Its place is occupied by the 
base of the black slate or Huron shale. (See the Reports on the Geology 
of Paulding County and of Defiance County.) This belt of Hamilton, or 
Upper Corniferous, as it has been styled in the reports on Sandusky and 
Seneca counties, crosses Highland and Defiance townships, underlying 
also the south-eastern portion of Richland. The black slate underlies 
Defiance city. The Maumee River runs over the black slate from near 
the point of its entrance within the county to within a mile and a half 
of the Henry county line. The remainder of the county is colored to 
represent the black slate, although it is not known, as already remarked, 
but higher formations succeed it in the northern towns of the county. 
The Drift is so uniformly spread as to hide the rock from view. 
The Huron Shale-—The only known exposures of the black slate are in 
the valleys of the Auglaize and the Maumee. Beginning on the south, 
the outcrop at the mouth of Powell’s Creek is the first and most import- 
ant, owing to the enterprise there started by Mr. Gleason of manufac- 
turing hydraulic cement from its lower beds. (See Geology of Marion 
County.) This ison the S. H.4 section 34, Defiance township, on the right 
bank of the Auglaize. The thickness of the black slate here developed 
_ is seventeen feet. This includes that passed through in digging a well 
at the same place. This well was drilled for the express purpose of test- 
_ ing the thickness of the slate. The drill then struck a very hard rock, 
which, after two or three hours’ drilling, was so little affected as to cause 
the abandonment of the well. The rock here struck can have been no 
