HURON COUNTY. 305 
BROKEN STRATA OF ERIE AND BEDFORD SHALES. 
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BED OF STREAM. 
The mass of the bluff is of Erie shale, with the hard bands which it 
contains broken up and tilted, but not removed from their connection 
with the including strata with which they are still in contact. The irreg- 
ular masses BB are “‘turtle-backs” of the Bedford shales buried in the 
mass of the Hrie. 
All these outcrops of rock occupy now substantially the same topo- 
graphical level. The Hrie shales alone are in their original beds. All 
the others have been disturbed and tilted, pushed out of their beds, and 
carried to a lower level by the ice. | 
In the immediate neighborhood, the Berea is exposed in several places 
dipping in various directions, and varying from 20° to 40°. These dis- 
turbances have left the Berea here resting on the Cleveland shales, and 
have so broken up and crushed the strata as to greatly impair the value 
of the quarries in the county. In a few places, even where the rock is 
tilted up to quite a sharp angle, the strata are still entire, and excellent 
rock can be quarried. At many of the openings, the broken, worthless 
rock largely exceeds that which is suitable for building purposes. 
BEDFORD SHALES. 
The section on page 303 exhibits the general character of the Bedford 
shales in this county. They are exposed only in the different branches 
of the Huron and Vermillion Rivers. Where undisturbed, they range 
from forty to seventy-five feet in thickness, and consist of hard, fine- 
grained sand-rock in their layers, alternating with thinner bands of 
argillaceous shales; the thicker strata of the sand-rock are frequently com- 
posed of a mass of the peculiar contorted rock called “turtle-back,” ren- 
dering it quite worthless. Sometimes, however, this formation yields a 
fair building stone. In places where quite a heavy bed of the Berea con- 
stitutes the surface rock, these shales are entirely wanting, the Berea 
resting upon the Cleveland shales. 
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