SOIL COMPOSITION 



69 



the nearest glacial ridges, are covered with several feet of loess. 

 The older glacial drift is usually loess-covered. The depth of loess 

 varies from three feet or less in the somewhat recent glaciations, 

 and in driftless areas, remote alike from the glacial borders and from 

 large stream courses, to eight or ten feet in areas near the borders 

 of the greatest glacial action; while in the "deep loess" areas 

 covering the bluff lands along some of the large streams the depth 

 of loessial material may be from ten to fifty feet or more. 



Some very complete analyses have been made of samples of 

 loess from widely separated areas. The results given in Table 1 1 

 are reported by the United States Geological Survey. The first 

 three represent loess deposits covering the bluffs at Galena, Illi- 

 nois; Vicksburg, Mississippi; and Kansas City, Missouri; while 

 the fourth " was taken from the summit of a ridge in the suburbs 

 of Dubuque, Iowa, at a point about 300 feet above the Mississippi 

 River." 



TABLE n. COMPOSITION OF LOESS DEPOSITS 

 Pounds in 2 Million of Loess 



