THE LANSING DEPOSIT NOT LOESS. 349 



color than the loess, and is much harder, as was revealed by 

 digging. As far as the writer was able to ascertain on the 

 accessible parts of the bluff, at this level much obscured by 

 talus, the transition from the gumbo to the loess above it is 

 quite abrupt, though no sharp line appears. The lower loess 

 is much softer than the gumbo, contains fossils, and is wholly 

 devoid of pebbles. It is true loess in all its characters. The 

 whole series much resembles that which is splendidly dis- 

 played in the first cut northeast of Carroll, Iowa, along the C. 

 G. W. Ry., and which is described in the following paper. In 

 both cases the distinction between the gumbo and loess is clear 

 enough. It may be added that in describing what appears to 

 be the same deposit at Emerson and Malvern, Iowa, Udden 

 says* that "the transition from this gumbo to the loess above 

 is usually well-marked." This gumbo is evidently not loess 

 and the writer knows of no point where these deposits occur 

 in the same exposure, where they cannot be as satisfactorily 

 differentiated as other pleistocene deposits. The confusion is 

 found in the literature of the subject rather than in the de- 

 posits themselves. While the line between loess and associated 

 deposits is not always sharp, the transition, excepting in cases 

 of evident rearrangement, takes place within very narrow 

 limits, — usually about one to three inches. There is however, 

 no such wholesale mingling of rock-materials and loess as 

 would be necessary to parallel the Lansing deposit. 



Professor Winchell intimates that "a typical loess deposit" 

 is a question of definition. While it is true that there has 

 been some difference of opinion as to what should be included 

 under the term in certain local cases, no very great doubt as 

 to what constitutes real loess was entertained until the publi- 

 cation of McGee's great report, and no more extreme applica- 

 tion of his definition has been attempted than in the case in 

 which it was so expanded as to cover the Lansing deposit 

 under discussion. A detailed discussion of some of the de- 



*Geol. of Mills and Fremont county, Iowa Geol. Sur. , vol. xiii, p. 

 167, 1903. 



