156 IOWA ACADEMY OF SCIENCES. 



on the loess by Prof. B. Shimek,"' "Is the Loess of Aqueous 

 Origin T'. he discusses the (juestioii of the loess, in which 

 he comes to the conclusion. 



"It seems evident that the loess materials originated 

 largely or wholly in drift, and as the comparatively recent 

 investigations by members of the Iowa geological survey 

 have demonstrated the presence of several drift sheets in 

 this state, and as Nebraska has at least two such sheets, an 

 interesting problem is suggested to geologists, namely: 

 the determination of the relation which the various depos- 

 its of loess bear to those drift sheets which during the 

 deposition of the loess were found at the surface of adja- 

 cent regions. This would involve a careful comparison of 

 the finer materials in the drift with loess, and the consid- 

 eration of the probable or possible direction and means of 

 transportation to the present location of the loess." 



In another paper on the same subject Prof. B. Shimekt 

 says: 



"The loess-fauna, of Council Bluffs, is thus not wholly 

 terrestrial, but with the exceptions noted,is almost identical 

 with the modern upland fauna of the same regions. Surely 

 no conditions of excessive moisture prevail in that region 

 today. 



"The amount of material carried by the winds need not 

 have been so great as is sometimes assumed. The estimate 

 made by the writer for the rate of deposition for eastern 

 loess (1 mm. per year), and that made by Keyes for west- 

 ern loess (one-tenth to one-fourth of an inch) would be 

 sufficient to form most of these deposits respectively in the 

 8,000 years, usually computed, since the recession of the 

 glaziers. 



"The objection made by Dr. Chamberlain that 'the eolian 

 deposits are measured, not by the quantity of silt borne by 

 the winds and lodged on the surface, but by the difference 

 between such lodgment and the erosion of the surface,' is 

 met, at least in part, by the theory offered, for it is a well- 

 known fact that timbered areas, even when very rough and 



•Proc. lo. Acad. Sci. 5 : 32. 



t The distribution of loess fossils. Proc, lo. Acad. Sci. 6 : 98. 



