698 ABSTRACTS OF PAPERS 



the formation. There appear to be five drift sheets exhibited in Wisconsin as 

 follows : 



First drift, a very old, thin drift ; second drift, a very old, thick drift, corre- 

 lated with the Kansan of northeastern Iowa ; third drift, a relatively old, thin 

 drift, correlated with the Iowan of northeastern Iowa ; fourth drift, a rela- 

 tively thin, fresh drift, correlated with the early Wisconsin of northeastern 

 Illinois; fifth drift, the Wisconsin drift. Extensive alluvial and lacustrine 

 deposits in old valleys and lowlands of interglacial origin between the second 

 and third drifts; the loess deposits of later origin than the third drift and 

 older than the fourth. 



IOWAN DRIFT 



BY FRANK LEVEEETT 



(Abstract) 



Dr. S. Weidman, of the Wisconsin Geological Survey, has found in western 

 Wisconsin an old drift sheet overlying the Kansan drift and extending in 

 places beyond its limits, whose state of weathering is about that of lllinoisan 

 drift. Its constitution there is unlike the underlying Kansan, and it lies in 

 and partially obliterates valleys of post-Kansan age. It has loose texture and 

 much gravelly material, and is so rapidly pervious to water that it has in 

 places suffered very little erosion and presents intact the features left by the 

 ice-sheet. It is thought by him to be a continuation and correlative of the 

 Iowan drift of northeastern Iowa. 



Drift of this sort has been noted by the present writer and by Doctor Weid- 

 man in Minnesota inside the limits of the Kansan drift; also in southern Wis- 

 consin and northwestern Illinois east of the Driftless Area, either overlying 

 or extending outside the typical lllinoisan drift. Its southern limits as fixed 

 by the present writer are at the Green River Basin in western Illinois, there 

 being typical lllinoisan farther south. 



This drift is not markedly different from lllinoisan in degree of weathering, 

 but differs from it in being more irregular in composition and more varied in 

 topography and depth. It includes the pre- Wisconsin eskers and kames of 

 northwestern Illinois and southern Wisconsin, and yet over wide areas is a 

 very scanty deposit. Similarly it includes the gravelly knolls of southeastern 

 Minnesota that obstruct the post-Kansan drainage lines. 



The so-called Iowan drift may stand in about as close relation to the llli- 

 noisan as do the later Wisconsin moraines to the earlier Wisconsin. It does not 

 seem to be separated from the lllinoisan drift by a definite interglacial stage, 

 but instead to represent a substage or stadium of the lllinoisan. It may, there- 

 fore, be advisable, pending further study, to apply to it the double name Later 

 lllinoisan or Iowan. 



Discussion 



Prof. A. P. Coleman: The name Keewatin is pronounced Keeneaytin and 

 not Keewattin. Was there not a migration of the glacial center from the 

 Keewatin area west of Hudson's Bay to the Patrician area, to coin a term from 

 the name of the new district of Patricia, and finally to the Labrador area? 



There are older striae running south in regions to the northwest of Lake 



