486 C. R. STAUFFER 



is correct, as seems probable, the Huron shale does not repre- 

 sent the Upper Hamilton, but rests unconformably on the Prout 

 or Encrinal limestone. 



Mr. Allen R. Stuckey, who has drilled numerous wells in 

 Crawford and adjoining counties, reports that at Bucyrus the 

 drift ranges from 55 to 80 feet in thickness. Under this is 35 to 

 200 feet of black shale, which is usually succeeded below by about 

 10 feet of gray shale, so tough and sticky that it is difficult to drill. 

 This gray shale immediately overlies the limestone, but in a few 

 wells it has been found to be absent where the black shale rests 



Fig. 5. — The Olentangy-Ohio shale contact at "Dripping Rock," near Liberty 

 Church, Delaware County, Ohio. Here again there is an undulating contact. 



directly upon the limestone. In the eastern part of this county, 

 30 feet of the gray shale is found at many places. It is evident, 

 therefore, that in Crawford County the Olentangy shale is even 

 more variable in thickness than it is in central Ohio and that the 

 Prout limestone of the Sandusky region has disappeared. At 

 "Dripping Rock" (Fig. 5), in Delaware County, where the Prout 

 limestone is wanting and the Olentangy shale is only about 31 feet 

 in thickness, the contact between it and the overlying Ohio shale 

 is most marked and slightly undulating. The contact is equally 

 marked at High Banks, near the Franklin-Delaware county line, 

 and again in the town of Delaware (Fig. 6). At this latter place 

 the basal Ohio shale is somewhat arenaceous. Near the Ohio 

 River, at Kinkead Springs, Pike County, the Ohio extends down 

 to the Silurian limestone and is firmly welded to it. 



