UNCONFORMITY OF BEDFORD AND BEREA FORMATIONS 659 



BLUE SHALE AT THE UNCONFORMITY 



In the bottom of all these deep channels in the horizon of the 

 red Bedford shale is a soft, dark-blue shale, three to four feet thick. 

 This blue shale is not found beneath the sandstone of the small 

 lenses in the Bedford horizon, nor is it found at any given horizon. 

 The bottoms of the quarries are at different depths with the dip of 

 the strata too slight to bring this blue shale to all the quarry floors. 

 The outcrop of the Ohio quarry channel on Chance Creek had no 

 blue shale beneath the sandstone, the sandstone resting directly 

 upon red Bedford shale. Yet this blue shale is found underlying 

 the sandstone in the Ohio pit. 



The reason for the location of this blue shale may be the follow- 

 ing: The lower and deeper portions of the valleys of the Bedford 

 streams became drowned. Sediment carried by the rivers into 

 these quiet bodies of water was deposited and eventually formed 

 this blue shale which occurs between the red Bedford shale and the 

 Berea sandstone. 



Dr. Hubbard and the writer made a careful search for fossils in 

 this blue shale, but none were found. 



CONCLUSION 



Starting a few miles east of Sandusky, Ohio, and extending 

 eastward to Cleveland, Ohio, there is a well-defined unconformity 

 between the Bedford and Berea formations. The unconformity, 

 however, extends over a greater area than the region above defined, 

 as it has been noted as far south as Fairfield County, Ohio. 



During the period that the Bedford horizon was above the level 

 of the sea, its surface was dissected, streams cutting deep channels 

 and wide valleys. The lower portions of these valleys became 

 drowned. In the quiet water thus formed, the rivers deposited 

 sediment which later became a blue shale, logically belonging to 

 the Berea formation. 



The entire Bedford land area gradually was submerged, and the 

 Berea sandstone formation was laid down. 



