KANSAX DRIFT ON SUB-AFTOXIAX 



1 ,1 ■ i 



SUPERIMPOSITION OF K AN SAX DRIFT ON SUB 

 AFTONIAN DRIFT IN EASTERN IOWA. 



MORRIS M. LEIGHTON. 



Many new exposures have been made by the Chicago, Mil- 

 waukee and St. Paul Railway in the reconstruction of their line 

 across Iowa. Various ones of these have proved to be of especial 

 interest to Pleistocene geologists, and among them are several 

 cuts in the northern part of Clinton county, showing superim- 

 position of the two oldest drifts, the Kansan drift on the Sub- 

 Aftonian drift. This paper is devoted to a description of these 

 and their interpretation. 



1. A significant exposure is located at the second viaduct one- 

 half mile east of Delmar Junction. The cut is through a divide 

 with a rounded summit. 250 to 300 yards long, and has a maxi- 

 mum depth of sixty feet. By reference to figure 13, A. the 

 relations of the following materials will be clear: 



K a rt » an 

 Till 



Af tonun 

 Sub- Af tonian 



T. /( 



Fig. 13 A — Diagrammatic sketch of the relations of the materials shown in 

 the south side of the Chicago, .Milwaukee and St. Paul railway cut, one- 

 half mile east of Delmar Junction. 



Fig. 13 B — Cross-section of the railway cut referred to in A. showing 



former track-level, m ; the position of the mineralized stump, c; and the 

 present track-level, n. 



