890 GEOLOGY OF OHIO. 



Limestone may be named as a very wide spread and persistent seam. It 

 takes its name from E wing Site, in the Sunday Creek Valley, where it is 

 a ferrugiaous limstone, five feet in thickaess, about eighty feet above the 

 Cambridge and forty feet below the Ames. It holds its place throughout 

 the counties southward to the Ohii River, and by its steadiuess, indeed, al- 

 most deserves to be counted in the first list. It weathers easily and is so 

 often hidden by the products of its own decomposition that it escapes 

 general notice. 



These, then, are the principal limestones at present known in the 

 Hanging Rock District. They constitute a very orderly and symmetrical 

 system. The suggestion of CroU, that the Coal Measures are the product 

 of a glacial period, the coal seams themselves, and equally the lime- 

 stones and ores with which they are associated, being interglacial 

 growths, finds ia this series its best illustration, and, perhaps, furnishes 

 the best explanation of the astronomical regularity with which these 

 horizons succeed each other. 



Each of the limestones named will ba briefly described. 



1. The Miixville or White Limestone. — It is harder to characterize the 

 Maxville limestone than any other in the series. The exposures of it 

 are few in number, and even these few exhibit great diversity of com- 

 position. The most valuable and, on the whole, the most characteristic 

 part of the stratum as seen at Maxville, Perry county, at Winona 

 Furnace, and at Logan, Hocking county, consists of a light drab- 

 colored limestone, very fine grained and homogeneous, generally poor 

 in fossils, breaking with a conchoidal fracture aud looking very like 

 lithographic stone. Other portions of the stratum are blueish in color, 

 and others still are colored green by silicate of iron. There is often 

 a notable quantity of this substance in the -clays that are found be- 

 tween the layers of the limestone. A light blue stone that is found 

 at the Winona Furnace drifts, is equal in quality to the portion already 

 described. It greatly resembles in appearance the famous Dayton Lime- 

 stone of Upper Silurian Age. The drab or white limestone yields at 

 its best over ninety per cent, of carbonate of lime, and is much esteemed 

 as furnace flux. The darker beds are generally rejected by the furnaces 

 as too silicious, but analysis shows that selection cannot properly be 

 made on the ground of color. 



It has already been stated that this formation is unsteady and irr<iqalar 

 in its occurrence. The best guide in following it is the persistent and 

 easily recogniz.-d horizon of the Zoar or Blue Limestone, whi'h, with its 

 blojk ores, is universally known throughout the district. The place of 

 the Maxv.ille is about one hundred feet below the Blue Limestone. The 



