HURON COUNTY. 



299 



bling in all respects the heavy clay lands in north-eastern Ohio, which 

 are underlain by the Cuyahoga shales. Large elms are also a character- 

 istic of the forests here. This surface, thoagh apparently level, slopes 

 uniformly and somewhat rapidly to the north, so that at the northern 

 part of the township it is only three hundred and eighty-five feet above 

 the Lake. The indurated rocks are here deeply buried beneath the 

 Drift which fills the broad, deep channel formerly connecting Vermillion 

 River with the head waters of the Mohican, and Ashland county. 



GEOLOGICAL STRUCTUEE. 



The geological structure of the county is easily made out, and com- 

 prises simply the Upper Devonian and the Lower Sub-Carboniferous 

 rocks, of which the following is an approximate general section : 



Ft. 

 Cuyahoga shale 100 



BereaGrit 50 to 75 



Bedforaehale 40 to 50 



Cleveland shale - 15 to 30 



Brleshale 15 to 33 



=S^ 6. Huron shale. 



700 



Hamilton group 10 to 15 



Corniferons limestone 50 



The exposed strata show evidences of much greater disturbance and 

 displacement than I have observed elsewhere in the State. Sharp syn- 

 clinal and anticlinal axes are visible in a majority of the rock exposures 

 above the Huron shales. These are most conspicuous in the Berea grit, 

 and will be more specifically described in connection with that deposit. 



CUYAHOGA ,: HALES. 



About one hundred feet of the lower part of the Cuyahoga shale under- 

 lie the south-eastern part of the county. This formation is frequently 

 exposed in the banks of Vermillion River and its tributaries, where the 

 harder layers are quarried for local use, and furnish building stone of 

 fair quality. The rock is a compact, fine-grained sandstone in rather 

 thin strata, containing what the quarrymen call turlle-bachs. These show 

 contorted lines of cleavage, which cause the rock to break up in rounded, 

 flattish masses, bearing a rough resemblance to the animal which has 



