174 FULLER AND CLAPP — MARL-LOESS OF LOWER WABASH VALLEY 



that the loess silts were carried southward from the lowan ice by slug- 

 gish but variable streams, and finally deposited as extensive flats, from 

 which vast quantities were taken up and redistributed by the winds, was 

 ably presented b}^ Professor Chamberlin,"^ and is now quite generally 

 accepted. The time for generalization as to origin of the loess as a whole 

 from observations in a single region appears to have passed, and the 

 origin in each localit}'' is best decided for itself by its own internal or 

 physiographic evidence. 



In arguing for the aqueous origin of the Wabash marl-loess the writers 

 are but following the views of most of the earlier writers, but they difi'er 

 from all except Owen,t in difierentiating the marl-loess of the immediate 

 \y abash valley from the common or upland loess on either side and 

 in basing their arguments upon the physical and chemical characters 

 and the topographic expression of the deposits themselves rather than 

 on a general assumption as to the conditions or on generalizations as 

 to the origin of the loess as a whole. 



Although the literature of the loess contains many descriptions of 

 material apparently similar to that along the Wabash river, it is not 

 permissible to assume a similar mode of origin without a full and careful 

 study of all the evidence which the deposits themselves afford. If the 

 evidences cited in the foregoing portions of the paper should prove to be 

 of any value, they may afford some aid in the discrimination of aqueous 

 and eolian deposits. 



References to Literature 



The following list, though known to be incomplete, gives some of the 

 more important papers presenting evidences similar to those described 

 in the present paper : 



Stratification and horizontal Banding 



1. Bain, H. F. : Geology of Plymouth county (Iowa). Iowa Geological Survey, 



volume 8, 1897, pages 318-366. 



2. Beyer, S. W. : Geology of Marshall county (Iowa). Iowa Geological Survey, 



volume 7, 1896, pages 197-262. 



3. Broadhead, G. C. : Origin of the loess. American Journal of Science, third 



series , volume 18, 1879, pages 427-428. 



4. Chamberlin, T. C, and R. D. Salisbury: Preliminary paper on the driftless 



area of the Upper Mississippi valley. United States Geological Survey, 

 Sixth Annual Report, 1885, pages 199-322. 



♦Supplementary hypothesis respecting the origin of the loess of the Mississippi valley. Jour. 

 Geol., vol. 5, pp. 794-802. 



t Indiana Geol. Survey, Second Rept., p. 5, 1838. The marl is apparently recognized as a dis- 

 tinct type of deposit. 



