ABSTRACTS AND DISCUSSIONS OF PAPERS 115 



The relation of geology to soil was brought out by (1) a comparison of the 

 chemical composition of a number of soils developed from the same rocks under 

 varying conditions ; (2) a comparison of the physical characteristics of a num- 

 ber of soils developed from the same rocks under varying conditions; (3) a 

 comparison of the physical characteristics of a number of soils developed from 

 different rocks under similar conditions ; (4) a comparison of the physical 

 characteristics of a number of soils developed from the same rocks under vary- 

 ing topographic conditions. 



Presented in abstract extemporaneously. 



GEOLOGIC SIGNIFICANCE AND GENETIC CLASSIFICATION OF ARKOSE 



DEPOSITS 



BY DONALD C. BARTON 1 



{Abstract) 



Different opinions are held as to the conditions under which arkose has been 

 formed. A study of arkose deposits shows that they are of several distinct 

 types, of which the more important are (a) deposits of great thickness and 

 with fresh feldspars, (6) deposits of moderate size associated with coal and 

 argillaceous beds, and (c) deposits of moderate size, more or less argillaceous 

 and associated with red beds. A survey of the conditions under which arkose 

 could be expected to form shows that the granular disintegration of granite 

 is widespread and is a possibility under practically all climates ; that in 

 rigorous climates erosion and deposition of the granitic sand can take place 

 contemporaneously with the disintegration, but that in regions of moist cli- 

 mate the mantle of vegetation must be critically weakened by some change of 

 conditions, such as a marine transgression or increasing aridity, before the 

 products of disintegration and decomposition beneath can be eroded and then 

 accumulated. It therefore seems possible to formulate a genetic classification 

 of arkose deposits. 



Presented by title in the absence of the author. 



SOME FEATURES OF THE KANSAN DRIFT IN SOUTHERN IOWA 

 BY GEORGE F. KAY 



(Abstract) 



In county reports issued by the Iowa Geological Survey and in other publi- 

 cations many of the features of the Kansan drift of southern Iowa have been 

 described, including the original Kansan drift plain, the present topography 

 of the Kansan drift, the tabular divides, the characteristics of the weathered 

 and unweathered zones of the Kansan drift, the gumbo, which is closely re- 

 lated to the Kansan drift, and the fine, loesslike clay overlying the Kansan 

 drift surface, and which has been interpreted by several investigators to be 

 material of eolian origin deposited after a mature topography had been devel- 

 oped on the Kansan drift. The origin of the gumbo has been interpreted 



1 Introduced by R. A. Daly. 



