886 GEOLOGY OF OHIO. 



preeminence here that it may be taken as the proper representative of 

 the whole field. This seam is known as the Limettone Ore. It gets its 

 name from the fact that it is, for the most part, immediately underlain 

 by a stratum of fossiliferous limestone, which is commonly called the 

 Gray Limestone through the country that it occupies. The stratum was 

 named by Prof. Andrews the Ferriferous Limestone, but, for reasons to be 

 hereafter given, it is termed in this report the Hanging Rock Limestone. 



Assuming this ore seam, then, to be the characteristic and determin- 

 ning feature of the Hanging Rock district, and counting in, as belonging 

 to it, all the furnaces that are.established on it, it will be found neces- 

 sary to extend the limits already named, by a few mile;?, so as to embrace 

 the new furnaces of the Hocking Valley that depend on the Baird Ore 

 -for their chief supply, the Baird ore being the name by which the lime- 

 stone ore is known in its northern developments. The south line of 

 Perry county thus becomes the northern boundary of the Hanging Rock 

 district. The western margin of the Coal Measures constitutes its liinit 

 in that direction, while, upon the frast, an equally irregular boundary is 

 formed in the sinuous line that marks the descent of the.limestone'cire 

 ' below drainage. Its southern limit is the Ohio River, for, though all the 

 elements of our geological scale can, be followed unchanged into Kentucky, 

 we have no immediate interest in them there. 



The present report will be confined to the discussion of one general 

 topic, viz., the airatigraphical order of the rocks that occupy this belt. Nor will 

 the whole series be considered here. Only that portion of it that begins 

 with the Zoar Limestone and ends with the Cambridge Limestone, will 

 be particularly treated, but two additional limestones, viz., the Maxville 

 and the Ames, will be employed in the classification. Incidentally, 

 the order of other parts of the series will be briefly discussed, and also 

 the economical values of many of the more important deposits, but the. 

 limits of available space make this restriction necessary. 

 '. 1. , This district embraces the Lower Coed Measures and part of the 

 Barren Measures of the generally received classification, in all amounting 

 to about seveii hundred feet, the Ames Limestone of Prof. Andrews being 

 taken as the upper limit. 



No two sections along this extended belt of country will prove exactly 

 identical. Strata change from mile to mile, and even from farm to farni, 

 somteimes in composition and sometimes in quality. Some are quite local 

 in character, disappearing abruptly; others are more persistent, and cam 

 be traced over wide areas. A few hold their relative positions throughout! 

 the field, but even these are subject to very important modifications. 

 The lime or ore of any one section may be replaced by flint in another. 



