GREENE COUNTY. 



679 



limited to the different representatives of the Cedarville division, but 

 various limestones of the State are included. 



III. DBIFT. 



The Drift of Greene county agrees so closely in all particulars with 

 that of the adjacent counties, already reported upon, that no extended 

 description will be given in this place. All of the distinguishing fea- 

 tures of this most interesting but perplexing formation are here shown 

 with great distinctness. In other words, the materials for a perfect 

 theory of the Drift are found spread over the rocky floor of Greene 



county. 



1. In the first place, the face of the Niagara limestone has been uni- 

 versally planed and polished by glacier agency. It does not, it is true, 

 show the marks of this agency every where, for the upper bed. of the 

 limestone have often been partially dissolved by the action of atmos- 

 pheric waters infiltrating through the Drift beds; but wherever the sur- 

 face has not been thus affected it exhibits the glaciated markings now 

 under consideration. These markings have been noted in every section 

 of the county in which the cliff limestone is exposed; but they are 

 shown most plainly in the uncovered surfaces of the Yellow Springs 

 quarry and of McDonald's quarry. The grooves and stria, have a direc- 

 tion in most instances of ten to fifteen degrees west of north In the 

 Yellow Springs quarry their line of direction cuts the line of direction 

 of the Glen, which is immediately adjoining, at an angle of about twenty 

 degrees, showing that even such deep furrows as this had no influence m 

 changing the course of the abrading ice-sheet. 



2 Over the polished surface of the rocks,,as well as over those more 

 extensive areas'where the rocks retain no markings of this kind, h * 

 in deposits of varying thickness, a covering of bowlder clay. This is an 



