36 GEOLOGY OF OHIO. 



The fire-clay found associated with it at several points in southern 

 Ohio is one of the most valuable deposits of this sort in our entire scale- 

 The outcrops of the limestone occur in Scioto, Jackson, Hocking. Perry 

 and Muskingum counties. It is reported in some of the well records of 

 Steubenville, Brilliant, Macksburg, Clarington and at several other points 

 in eastern Ohio. 



There remains to be briefly described the great Carboniferous system 

 of Ohio. An extended and more careful review of its composition will 

 be given in succeeding chapters of the present volume, and it will be 

 enough, at this point, to set in order its more striking features. There is 

 a question as to the divisibility of the lower portion of the series. The 

 Pennsylvania geologists describe as the conglomerate series a number of 

 strata, including several beds of coal, limestone and iron ore, that have 

 been counted members of the true Coal Measures in most of the 

 volumes of our Ohio geology. The grounds for such division . are, with- 

 out doubt, much more imperative when the formations are studied in 

 Pennsjdvania and the Virginias. So far as the Ohio series is concerned, 

 it is not probable that any division would have been called for on this 

 ground, but, for the sake of the general order, the classification recog- 

 nized in Pennsylvania and to the southward will be adopted here. 



13. The Conglomerate Group. 



This group consists of three great sandstones, between which and in 



which are distributed two thin but persistent limestones and four coal 



seams, several of them of considerable value. The order is shown in the 



table below. A fifth coal seam is occasionally found. 



f Home wood Sandstone. 

 (Tionesta Coal). 



(Ore. 

 Upper Mercer Group. < Limestone. 



( Coal, No. 3 a. Newberry, 

 f Ore. 

 Conglomerate group. -{ Lower Mercer Group. -J Limestone. 



( Coal, No. 3, Newberry. 

 Massillon Sandstone, Upper. 

 (Ouakertown Coal). Coal No. 2, Newberry. 

 Massillon Sandstone, Lower. 

 Sharon Coal — Coal No. 1, Newberry. 

 l_ Sharon Conglomerate. 



This group has an average thickness of two hundred and fifty feet, 

 though the range of the formation is considerable. 



14. The Lower Coal Measures. 



This division includes the most important section of the Coal 

 Measures, so far as Ohio is concerned. 



In it are found six seams of coal, four horizons of limestone, two of 

 which are marine in origin, and several valuable iron ores and fire-clavs. 

 A detailed account of the composition of this important division will be 



