50 
IOWA ACADEMY OP SCIENCES. 
The dotted line represents the boundary line between the sur- 
face outcrops of the Des Moines strata on the east and the 
Winterset strata on the west. The main points of difference 
FJg. 1. Present drainage of Madison county , 
are as follows: The drainage of Jefferson township was south- 
eastward along the front of the Winterset limestone to North 
river. Because of the drift, Badger creek now flows northeast- 
ward over the drift across Jefferson township, then southeast- 
ward across the pre-Kansan divide, then eastward across Lee 
township. The stream seems to follow pre- Kansan ravines, 
but does not cut through the drift. 
A preglacial valley extends southwestward from the western 
part of Lincoln township across the southeastern part of Web- 
ster township and thence across Grand River township. This 
old valley is now completely filled by drift, and the drainage, 
which was formerly turned toward Middle river, is now turned 
