BEREA SANDSTONE IN ERODED CLEVELAND SHALE 771 



slanting side of the Berea sandstone at its contact with the gray 

 shale of the present day marks the side of this old channel. 



THE BEDFORD-BEREA UNCONFORMITY AND THE DEVONIAN- 

 CARBONIFEROUS LINE 



Some geologists have questioned the erosion of the Bedford 

 formation prior to the deposition of the Berea, as being of much 

 value in determining the position of the Devonian-Carboniferous 

 Hne. They argue that the time would be very short indeed, 

 geologically, in order that the soft Bedford shale might be worn 

 away to the extent which we find it, and that the cycle of erosion 

 would therefore be of very slight importance. 



Hence, an eroded channel in the Cleveland shale of the magni- 

 tude of the one described should help to show that the period of 

 erosion of the Bedford was of much longer duration than was to be 

 inferred by the channels in the soft Bedford shale, for the rather hard 

 Cleveland shale is not especially easy to erode. The time required 

 in the removal of the Cleveland would be far greater than that 

 required in any of the Bedford channels. 



Therefore, the interval of erosion of the Bedford prior to the 

 Berea deposition was of greater length than has been shown by 

 any other evidence set forth up to the present time. 



Consequently, the Berea sandstone filled channel in the eroded 

 horizon of the Cleveland shale acts as evidence in favor of placing 

 the Devonian-Carboniferous line between the Bedford and Berea 

 formations. 



