OF DENISON UNIVERSITY. 47 



drift deposit already referred to. This cut is a mile or so in 

 length and of varying depths until at Hanover the railroad again 

 emerges into the open valley which continued west to Newark. 



6. The Course of the Preglacial Muskingum. 



The facts already given indicate that preglacial drainage of 

 the upper Muskingum and Tuscarawas valleys, with a depth of 

 150 feet below the present streams, was through the preglacial 

 Muskingum channel past the morainic dam at Hanover, which 

 has a valley depth at least 150 feet below the Muskingum at 

 Dresden, into the Licking system at Newark, with a valley 

 depth of over 300 feet below the present river. North and 

 west from Newark the valleys are all rock bound and the 

 streams rise in rocky table lands. East, the present Licking 

 river is flowing in a postglacial channel. South, the county is flat 

 and covered with a lacustrine deposit. The divide between the 

 present South Fork of the Licking and the Scioto basin near 

 the Licking Reservoir is about 150 feet above Newark but no 

 rock is exposed in this region. The line of rocky hills extends 

 south from Newark and passes east of the Reservoir and then 

 bends west towards Lancaster. 



Gas wells at Thurston and Basil show a depth of drift of 

 over 335 feet. This would make the rock floor in this direction 

 at least 300 feet below the present river drainage at Newark or 

 584 feet A. T. West of Thurston extends the great drift plain 

 of the Scioto valley and no rock is known in this direction. 



This, then, must be considered the direction of outflow for 

 the preglacial basins of the present Licking and Muskingum 

 rivers. Beyond Newark this old valley made a bend to the 

 south and west and entered the Scioto system south of Colum- 

 bus. 



7. Probable Causes which Produced the Changes in the 

 Drainage of the Muskingum and Licking Rivers. 



In order to find any satisfactory explanation for the com- 

 plicated topography of the Licking and Muskingum basins the 



