GREENE COUNTY. 669 



mile or two beyond, to the east and north, the horizon of the Dayton 

 stone is shown in many exposures with perfect distinctness; but its 

 place is occupied by light-blue shale, or soapstone, as it is popularly 

 called, and a worthless shaly limestone, yellow in color, and generally 

 covered with fucoidal impressions, which are frequently rendered green 

 by the presence of silicate of iron. This phase is well shown on the 

 Grinnell pike, opposite the farm of Mr. A. V. Sizer, a mile below Yellow 

 Springs. 



By far the best known deposit of the Dayton stone in the county, how- 

 ever, is found on the McDonald farm, three and a half miles south of 

 Xenia. The rock was originally exposed here along a tributary Of 

 Cesar's Creek. When the quarries were first opened, but a light covering 

 of glacial Drift, or bowlder clay, was found; but as the lines have been 

 extended, the stripping has become heavier. The surface of the rock 

 has been planed and polished by glacier agency. From four to eight feet 

 of workable rock are here found, divided into courses varying from four 

 to twenty inches in thickness. The stone finds market in Xenia, being 

 quite widely distributed from that point by railroad. 



The composition of the stone from the McDonald quarry is seen in the 

 following analysis, made by Prof. Wormley: 



Carbonate of lime 84.50 



Carbonate of magnesia 11.16 



Alumina and iron ■; 200 



Silicious •- • 2 - 20 



99.86 



(6.) The Niagara shale directly overlies the Dayton stone where the 

 latter stratum is found, and the Clinton formation, in case the Dayton 

 stone is wanting. It is a normal constituent of the general geological 

 scale of the country. Eighty-five feet of it are found at the Falls erf Ni- 

 agara, and along the Appalachain Chain it is thickened to one thousand 

 five hundred feet. Its maximum development in Greene county can be 

 seen in the "Glen" at Yellow Springs, on the land of W. C. Neff, Esq., 

 and at the locality already noted, in the cutting for the Grinnell pike, 

 opposite the old water-cure gounds. It here attains a thickness of thirty 

 feet This member of the series increases rapidly as it is followed south- 

 ward through the State, measuring in Adams county one hundred and 



six feet. , 



In composition it is not perfectly uniform, the two elements that enter 

 into it being found in varying proportions in different sections. These two 

 elements have been already named-a light-blue calcareous shale, and 



