1L P. Cushing — Age of the Cleveland Shale of Ohio. 581 



Art. XLVIII. — The Age of the Cleveland Shale of Ohio ; 

 by H. P. Cushing. 



Introduction. — In the February number of this Journal 

 appeared an article entitled " Unconformity at the Base of the 

 Chattanooga Shale in Kentucky.' 1 In addition to describing 

 the unconformity, the author endeavors to fix its date and 

 its duration, and this endeavor leads to a discussion of the age 

 of certain rocks in Ohio with which I have some familiarity. 

 The author also expresses his personal opinion of the correct- 

 ness of the work of certain geologists, in part no longer living, 

 and since I think that in one notable instance his judgment is 

 at fault, I wish also to say a word concerning it. 



That the Newberry Survey erred in correlating the Cleveland 

 shale of northern Ohio with the Sunbury (Waverly black shale) 

 of southern Ohio was but natural, and was later freely acknowl- 

 edged by Dr. Newberry himself ; the error of correlating the 

 black shale along the lake shore west of Cleveland with the 

 Huron shale he himself corrected later, as Mr. Kindle points 

 out. But it seems to me that neither of these has the remotest 

 connection with the argument given in the following quotation: 



" When Prof. .Newberry found himself unable to substan- 

 tiate his previously published statement of the occurrence of a 

 Waverly fauna at the base of the Cleveland shale, he continued 

 to maintain the Carboniferous age of the formation chiefly on 

 the evidence of the occurrence in it of three genera of Carbon- 

 iferous fishes, namely, Hoplonchus, Orodus, and Polyrhizodus.* 

 Concerning this evidence it is well to recall that most of the 

 fossil fishes described by Newberry were obtained for him by 

 collectors on whom he depended for the correct designation of 

 their. geologic horizon. Since Prof. Newberry had himself con- 

 fused the Sunbury and Cleveland shales, the opportunities 

 which existed for the collectors to confuse them are too evident 

 to require discussion." f 



Now, leaving wholly aside the question as to the accuracy of 

 the work of the group of excellent geologists who constituted 

 the corps of the Second G-eological Survey, what I wish to 

 point out is that there was practically no opportunity for con- 

 fusion of these two formations, in so far as toese three genera 

 of fishes were concerned. All three are described from the 

 Cleveland shale at Bedford.^ Because the Cleveland and 

 Sunbury were confused in a long-range correlation the full 

 width of the State, is far from making it " too evident to 

 require discussion" that the two were confused at a single 



*Mon. xvi, TJ. S. G. S., p. 123. 



\ This Journal. Feb. 1912, p. 132. 



% Geol. Surv. Ohio, Pal., vol. ii, pp. 50, 51, 55. 



Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 198.— June, 1912. 



38 



\ 



