662 GEOLOGY OF OHIO. 



safely estimated to be not less than six hundred and fifty feet above 

 Cincinnati, or eleven hundred feet above the sea. There 'is but little 

 difference in the elevations of these dividing ridges. The summits of 

 each consist of stratified beds of sand and gravel belonging to the 

 latest stage of the Drift period. The highest elevation held by the 

 bedded rock is probably in Miami township, to the north and north-west 

 of Yellow Springs. 



The elevations of a few of the principal points in the county are here 

 appended, almost all of which were determined for the Survey by Frank- 

 lin C. Hill, Esq., of Yellow Springs. All are counted above low water at 

 Cincinnati : 



Feet. 



Xenia, grade of railroad at depot 491 



Yellow Springs, grade of railroad at depot 541 



Osborne, " " 410 



Spring Valley, " " 333 



Claysville, " " 321 



Harbine's Station, " " 370 



Oldtown, " " 396 



Goe's Station, " " 427 



Berrybill's Hill, Spring Valley township (outlier of cliff limestone) 560 



Shoup's quarry, two miles south -west of Harbkie's (outlier of cliff lime- 

 stone) 519 



Gravel bank, Yellow Springs, about 625 



Railroad grade, one mile north of Yellow Springs (north line of county), 



about 600 



Cedarville (railroad grade), about 550 



Low water at Cincinnati is four hundred and thirty-two feet above the 

 sea. By adding, therefore, four hundred and thirty-two feet to each of 

 these elevations, the level above the sea is obtained. 



II. GEOLOGICAL SERIES. 



The geological scale of Greene county is identical with that of Mont- 

 gomery and Clarke counties, already reported upon. Its rock formations 

 are confined to two great series, viz., those of Upper and Lower Silurian 

 age; and between them the surface of the county is almost equally di- 

 vided, as is shown on the appended map. 



A vertical section of the rocks of the county would be found to contain 

 the following elements : 



3. Niagara Group. 



2. Clinton Limestone. 



1. Cincinnati Series, Lebanon division. 



The lowest division has an aggregate thickness of two hundred and 

 fifty feet, the middle division of fifty feet, and the uppermost of one 



