OLENTANGY SHALE AND DEVONIAN DEPOSITS 481 



especially shaly, as is often the case, the fauna tends to revert to 

 that of the more typical Marcellus, so that these forms are not 

 limited to the basal portion. But the occurrence in it of certain 

 fossil forms more characteristic of the true Hamilton beds of New 

 York than of the Marcellus of that region has led to the use of 

 Marcellus-Hamilton or Lower Hamilton for the Delaware. In 

 this use of the Hamilton, it is the older and broader sense of that 

 term, rather than the restricted present usage, that was intended. 

 It would more properly be called the lower Erian. The Olentangy 



Fig. 3. — A bank of Olentangy shale downstream a short distance from the one 

 illustrated in Fig. 2. 



shale is overlaid by the Ohio shale in the central part of the state 

 and by the Huron or lower Ohio shale at Sandusky. The strati- 

 graphic position of the blue shale in question, therefore, suggests 

 the same correlation that has been made on the meager fauna and 

 the lithological similarity. When it is recalled that the regions 

 in question lie within the same Devonian basin and that the deposits 

 are a continuation of the same general line of Devonian outcrops, 

 traceable by well-records in the covered interval between, this 

 relationship seems worthy of consideration. 



The relation of the Sandusky deposit to the Hamilton beds of 

 Ontario is much more easily determined. In a memoir on the 

 Devonian of southwestern Ontario, which was recently published by 

 the Geological Survey of Canada, the correlation of the shale below 

 the Prout limestone with the Olentangy has been adopted, and the 



