THE PREGLACIAL DRAINAGE OF OHIO. 75 



the river. As such they must continue to exist until a greater 

 elevation above sea level of the interior region permits the Ohio 

 and Mississippi to scour their channels deeper than the present 

 grade lines will allow them to do. 



The extensive drift deposits south of Cincinnati have not 

 yet been accounted for in a satisfactory manner. Professor 

 Wright says that the great masses of conglomerate two miles 

 below Aurora, Indiana, are the terminal moraine. Only a casual 

 inspection is needed to show that this assertion is entirely un- 

 founded. There are similar deposits farther down, and at a much 

 greater altitude, which he has overlooked, or at least not 

 mentioned. A careful examination of this entire territory is 

 required in order to determine the limit of the ice sheet ; to 

 ascertain what part it may have taken in the surface changes 

 below Lawrenceburg to estimate the relative elevation of the 

 hills at Madison and those where these deposits are found ; and 

 to discover the probable causes which led to the gravel deposits 

 upon the high lands in Boone county, Kentucky. 



