1 80 ERA NK LE VERE TT 



In southwestern Carroll county, Illinois, there are extensive 

 exposures of a soil at the base of the loess, made by the 

 Chicago, Burlington and Northern Railway Company, the loess 

 having been removed to make a fill across the valley of John- 

 son Creek. Probably a half acre of the buried soil is here 

 exposed to view. It has a deep black color to a depth of 10 

 or 12 inches, beneath which it assumes a greenish yellow color, 

 such as is presented by subsoils beneath poorly drained regions. 

 This subsoil is leached as far down as exposed, a depth of three 

 feet. This locality was visited last November by Professors 

 Calvin, Udden, Bain, and myself, and each recognized the 

 clear indications of a long interval prior to the loess depo- 

 sition. It may be noted in this connection that Judge James 

 Shaw mentioned a soil in Carroll county in his report on the 

 Geology of Illinois, which apparently has the same horizon as 

 the one just described. It was found at a depth of 15 feet 

 and a deposit of wood two or three feet in thickness was asso- 

 ciated with it. 1 



On the portion of the Illinoian sheet in southeastern Iowa 

 many excellent exposures of the Sangamon soil are found. 

 An exposure similar to that in Carroll county, Illinois, has been 

 made at West Point, Iowa, where the Chicago, Ft. Madison and 

 Des Moines Railway Company has excavated to obtain filling 

 for its tracks. The loess has been removed over an area several 

 rods square, leaving the buried soil at the base of the excava- 

 tion. Although the exposure is on the crest of the ridge which 

 marks the western limits of the Illinoian drift, the soil is of a deep 

 black color and has a depth of several inches. This exposure was 

 visited by Professor Chamberlin, Dr. Bain, and myself in August 

 1896, as were also several roadside exposures between West 

 Point and Denmark, and between Denmark and Ft. Madison. 



Exposures in other portions of southeastern Iowa are given in 

 connection with the discussion of the Yarmouth weathered zone. 



Valley excavation during the Sangamon interglacial stage.- — The 

 large streams in western Illinois and southeastern Iowa are 



1 Geology of Illinois, Vol. V, p. 80. 



