DEFINITION OF THE CARBONIFEROUS. 33 



described, we have ventured to liope that such changes would but slightly 

 impair the usefulness of the attempt to refer our species to definite horizons 

 and thus form the basis for correlation and generalization. In this attempt 

 we have been reasonably successful and feel confident that, with a dozen 

 species of well-preserved fossils from any given stratum, the stratigraphical 

 position can generally be determined within a few feet. 



Reference to current discussion as to the limits of the Carboniferous sys- 

 tem may seem necessary, but in the light of recent revelations the search for 

 a hard and fast line of demarkation between Devonian and Carboniferous 

 seems futile. For our own part, the convenience of the time-honored nomen- 

 clature and the application of the law of priority outweigh all other consid- 

 erations yet advanced, unless the whole Sub-Carboniferous group be dropped 

 and the Paleozoic be restored to its primitive simplicity — Silurian, Devonian, 

 Carboniferous — with only a single series of coordinate terms included in 

 each ; in which case one might let the Berea grit form the base of the Car- 

 boniferous.* 



The General Stratigraphy. 



About the Ohio Waverly the sequence has proved quite simple in central 

 Ohio, but curious misapprehensions have been perpetuated up to the present 

 moment. While Professor Andrews was the first to distinguish the great 

 mass of shales, freestones and conglomerates previously confused with the 

 Carboniferous conglomerate, he introduced so many elements of error that 

 his discovery was nearly unfruitful. To Professor Orton belongs the credit 

 of first distinctly differentiating on purely stratigraphical grounds the Cuya- 

 hoga shales from the typical Waverly of central and southern Ohio. And 

 we may claim the task of carrying out (though quite independently) the 

 minuter subdivision and correlation of the several horizons in the southern 

 part of the Waverly domain. It was a great misfortune that Dr. Newberry's 

 studies of the Waverly were so largely restricted to and based upon the 

 northern exposures which, as we shall see, contain only a poor one-third of 

 the series. The most recent discussion of the problems here touched upon is 

 that contained in Professor Orton's volume VI of the reports of the Geological 

 Survey of Ohio. It will, therefore, be convenient to summarize the results 

 of our W'Ork by reference to that report, and it will, of course, be understood 

 that this reference is not in the nature of criticism, but rather to facilitate 

 comparison with the most conservative and adequate basis for an under- 

 standing of the Waverly which up to this time exists. 



The Bedford Shale. — This argillaceous bed has been considered the base 

 of the Waverly, and is so constant and, in southern and central Ohio, so dis- 



*Cf. the suggestion of Professor Williams in the present volume, p. 19. 



