to the Ohio Shale Problem. 173 



Olmsted and Cleveland certainly, and most probably also the 

 Huron, thin eastwardly and disappear entirely from the sec- 

 tion before reaching the Pennsylvania line. 



The great number of deep wells that have been drilled since 

 Newberry's day in every part of Ohio in search of oil and gas 

 have thrown a vast amount of light on the underground 

 geology of the state. This new and otherwise unattainable 

 information has already enabled us to correct many misappre- 

 hensions ; and its use is by no means yet exhausted. It was 

 the well records that induced Orton to abandon Newberry's 

 view respecting the Huron in central Ohio, and to claim that 

 the black shale series here " comprises all of the elements of 

 the northern section. In other wordSj the so-called Huron 

 shale of central Ohio is the Cleveland, Erie, Huron shale of 

 northern Ohio." 



Orton's quoted view helped matters considerably ; and it is 

 the accepted view today. But is it quite true ? I believe not. 

 As stated in the remarks on the Olmsted, I can not admit that 

 any of the beds in the Ohio shale outcrops in central and 

 southern Ohio are continuous with or of the age of the typical 

 Chagrin in northeastern Ohio. On the contrary, the supposed 

 representative of the Chagrin in the Ohio shale is the 

 expanded southerly extension of the Olmsted, which, together 

 with the underlying Huron and the overlying Cleveland shales, 

 constitute a single formation or group that is but indefinitely 

 divisible into the three lithologic members. The distinction 

 of these members seems to grow more and more indefinite in a 

 southerly direction from the lake shore, and to the south of 

 the Ohio it is perhaps impossible to draw the lines between 

 them with any degree of certainty. Even along Lake Erie I 

 question if the top and bottom of the Olmsted can be every- 

 where sharply delineated. 



Hates of thinning of shale complex as shown in deep wells. — 

 As has been mentioned, the chief datum plane of the drillers in 

 eastern Ohio is the Berea grit. The interval between the 

 Berea grit and the underlying Devonian limestone is usually 

 referred to as the Bedford and Ohio shales and reported as a 

 unit. Now and then the Bedford is distinguished, especially 

 when the red in its coloring matter is conspicuously devel- 

 oped. For the purposes of this discussion it will suffice to 

 follow the drillers in lumping the shale mass beneath the 

 Berea into a single undifferentiated complex. The term shale 

 complex should therefore be understood as referring to this 

 mass. 



The complex as developed in a band some 30 or 40 miles 

 wide, crossing the state in a north-south direction and bounded 



* Ohio Geol. Survey, vol. vi, p. 25, 1888. 



