7i8 O. W. WILLCOX 



the yellow loess, is, at a maximum, about twelve feet in thickness, 

 the white loess about six, and the red about four or five. Westward 

 of Red Oak both the red and the yellow loess increase in thickness 

 relatively to the white loess, which finally disappears in this direction. 

 The yellow loess then rests directly on the red loess. To the eastward 

 of Red Oak the reverse is true; the yellow and the red both decrease in 

 thickness. In a sixty-foot cut two miles east of Red Oak the red 

 loess is wanting; the white loess, eight feet in thickness, rests directly 

 on the ferretto. Near the Adams county line the yellow loess appears 

 to be very much reduced. East of Corning the surface loess resem- 

 bles the white loess and may be identical with it ; the resemblance here 

 imputed refers both to fresh and weathered sections. 



The most favorable place for studying these deposits and the rela- 

 tions between them are: in the cut just east of the depot at Red Oak, 

 south of the depot in the bluffs left in excavations made by the rail- 

 road for material for fills, and in the cuts on the divide between the 

 East Nishnabotna River and Walnut Creek. 



As regards the propriety of designating the white and red deposits 

 herein described as loess, there can be little question. They are 

 deposits of loess for practically the same reasons that have been urged 

 in the case of the yellow loess, the eolian origin of which has now 

 been conceded by most geologists. Like the yellow loess, they con- 

 form, blanket fashion, to the inequalities of the pre-loessial topog- 

 raphy; like the yellow loess, they are invariably thickest on the crests 

 and brows of the erosional hills carved out of the old Kansan drift- 

 plain. They are not to be considered as of subaqueous origin for 

 the reason that no conclusive evidence has been obtained that the 

 region in which they are found was ever submerged beneath such a 

 large body of water as would have been a condition necessary to their 

 deposition. 



The red loess is evidently no mere local deposit. It has been 

 observed in Pottawattamie county, which hes north of Montgomery 

 county, by Udden,' who describes it under the name of "gumbo." 



I Iowa Geological Survey, Vol. XI, p. 255. The writer has examined the red 

 deposit described by Udden as occurring under the yellow loess at Minden, and has 

 satisfied himself of its loessial nature as herein defined. It may be remarked that 

 the name "gumbo," as applied to the red loess, is apt to prove a confusing misuse of a 



