GEOLOGICAL SCALE AND STRUCTURE. 27 



which were quite widely distributed throughout central and southern 

 Ohio, as far back as fifty years ago. Associated with the sandstone at 

 this locality, and everj-where throughout the district, were several other 

 strata that were always counted as members of the group by the geolo- 

 gists who gave the name. In fact, the boundaries were made definite and 

 were easily applied. The Waverly group extended, by its definition and 

 by unbroken usage in our early geology, from the top of the great black 

 shale to the Coal Measure conglomerate. This latter element was, in a 

 part of the field, confused with the Waverly conglomerate, afterwards 

 recognized and defined by Andrews, until a recent date, it is true, but the 

 intent of the geologists is apparent, and many of their sections were com- 

 plete and accurate. If the term Waverly is to be retained in our classifi- 

 cation, and it bids fair to be, every interest would be served by recogniz- 

 ing and retaining the original boundaries. The departure from them that 

 has been proposed has led already to more or less confusion. To make 

 the Cleveland shale the base of the Waverly is, as has been already shown, 

 to turn the entire shale stratum into a no-man's land. Aside from a few 

 sections in northern Ohio, where an arbitrary limit was fixed for this 

 upper division, there is no place in the state where a line can be drawn 

 with any approach to a certainty between Cleveland and Erie, or between 

 Erie and Huron. The plan was proposed before the true equivalence of 

 the northern and southern ends of the column had been established. If 

 the fact that the Cleveland shale of northern Ohio forms the top of the 

 great shale of central and southern Ohio had been known, it is doubtful 

 whether any proposal would have been made to break into this undivided 

 and indivisible series, which had been held to underlie the Waverly group, 

 ever since the name was first applied. 



11a. The Bedford Shale. 



At Waverly and in its vicinity, numerous sections are afforded 

 reaching from the black shale to the Waverly sandstone courses. This 

 interval ranges from fifty to ninety feet in thickness, and its boundaries 

 are generally clear and distinct. It is occupied with shales, light blue or 

 gray for the most part, but sometimes reddened in the lower portion 

 with peroxide of iron. The latter phase is seen in the excellent section 

 found at Piketon. These shales are thin-bedded, occasionally inter- 

 rupted with fine-grained sandstone courses, and sometimes carrying un- 

 gainly masses of the same material, nodular or rudely concretionary in 

 shape. The beds are almost entirely destitute of fossils, aside from the 

 burrows of sea-worms, which are found on the surfaces of most of the 

 layers, often preserved with great sharpness of outline. At a few points, 

 however, fossiliferous bands, containing a considerable number of species, 

 are found. These have recently been pointed out by Prof. C. L> Her- 

 rick, and an account of some of these fossils will be found in his con- 



