THE IOW AN DRIFT 591 



decomposition — lends strong support to the view that the Iowan 

 is separated from the Kansan by a very long interval of time. 



The relative youth of the Iowan may, or may not, be indicated 

 by the fact that in places the formation is still very calcareous up 

 to the grass roots. A concrete illustration of calcareous Iowan is 

 seen in a shallow well near the northwest corner of the southeast 

 quarter of Section 21, Township 95, Range 17. It should be stated 



Fig. 5. — View at the Dykeman quarry in Section 26, Township 97, Range 17, 

 showing part of an area of thin drift, in which neither Iowan, Kansan, nor Nebraskan 

 can be recognized. 



that the later investigations show that this young drift is variable 

 as to the amount of the lime content; for in such localities as that 

 just cited it seems to be as rich in calcium carbonate as the Wis- 

 consin, while in other places it gives no reaction with acid. The 

 original statement concerning this constituent of the Iowan drift 

 was based on facts which remain true for the localities which had 

 then been tested; but the writer has long since ceased to attach 

 much importance to the acid test as a basis for determining the 



