BORDER OF THE ILLINOIAN DRIFT. 225 



From Jonathan Creek the course is northward across a projecting part 

 of Muskingum County to the "National road," about 2 miles west of Mount 

 Stei'ling. It then changes to a course west of north and comes to the 

 Licking Valley at Hanover, 8 miles east of the city of Newark. The great 

 filling produced in the Licking Valley at the di-ift border is discussed below. 



From the Licking Valley the border bears east of north past Fallsburg 

 and comes to Wahatomaka Creek at Frampton, in the extreme southeast 

 corner of Knox County. It continues with the same course to the Wal- 

 honding River, passing about 2 miles east of New Guilford, in Coshocton 

 County, and coming to the river about 2 miles east of Walhonding. From 

 this river the course is slightly west of north, following nearly the divide 

 between the tributaries of Killbuck and Mohican creeks to the Wisconsin 

 drift border a short distance west of Nashville, Holmes County. The Wis- 

 consin drift apparently conceals its further course in northeastern Ohio. 



It will be observed that the drift border just outlined forms a great loop 

 with a length of about 400 miles, embracing an area whose width is nearly 

 250 miles. The boi'der at its southernmost point, near Louisville, Ky., 

 reaches latitude 38° 20', which is nearly one degree farther north than the 

 extreme limit reached by the Illinoian drift of the Illinois glacial lobe, the 

 limits of that lobe being about 37° 35'. The reentrant in northern Monroe 

 County, Ind., extends up to 39° 20', giving the lobe on the east a protrusion 

 of about 70 miles at its extreme point. The terminal portion of the loop 

 has an indentation near Cincinnati of 15 or 20 miles, producing an incipient 

 double lobation. The drift border on the east side of this area has a 

 remarkable retreat to the north, the point where the Illinoian border 

 disappears beneath the Wisconsin in western Holmes County, Ohio, being 

 about latitude 40° 40', or more than two degrees north of the southern 

 extremity of the lobe. 



To one examining into the causes of this irregularity of outline in the 

 drift border, several topographic features at once present themselves. The 

 reentrant angle in south-central Indiana lies between the great lobes, one 

 of which moved southward through the Lake Michigan Basin, and the other 

 through the Huron-Erie Basin. This, it is thought, will in large part 

 account for its remaining unglaciated. The Lake Michigan Basin and the 

 country to the southwest being an exceptionally low area, the ice sheet 

 extended farther south than in the somewhat elevated area between Lakes 



MON XLI 15 



