THE WEATHERED ZONE 24 1 



This exposure was visited by Professor T. C. Chamberlin 

 and Dr. H. F. Bain in August 1896 and by each the black 

 material beneath the till was considered a typical soil, and the 

 gray material below a typical subsoil. The slightly pebbly 

 brown clay beneath this subsoil shows no response with acid. 

 Other exposures, however, have been found in which a response 

 with acid may be obtained within six feet below the base of the 

 lower or Yarmouth soil. 



Between West Point and Denmark, a distance of seven miles, 

 records of thirteen wells have been obtained in which a soil was 

 found between the Illinoian and Kansan till sheets. The thick- 

 ness of the soil ranges from 2 to 5 feet and its depth below the 

 surface ranges from 16 to 45 feet; the usual distance to the soil 

 is about 30 feet. This represents, therefore, the combined thick- 

 ness of the Iowan loess and Illinoian till sheet. The loess, how- 

 ever, has a depth of but 5 to 10 feet. Of several wells made at 

 Denmark in 1894 to 1897 the writer has witnessed the excava- 

 tion, and finds that the leaching beneath the lower soil extends 

 about 6 feet into the Kansan till sheet. One of the most satis- 

 factory sections near Denmark is the following, made on the farm 

 of Mrs. Van Tuyl : 



Feet. 



Surface silt or loess of yellow color slightly calcareous and 



containing a few small pebbles near base, 7 

 Brownish yellow till, slightly calcareous and with few 



pebbles (Illinoian), - - - - - - - 10 



Brownish yellow till very pebbly and calcareous (Illinoian), 8 



Blue clay with few pebbles (Illinoian), - - - - 10 



Black mucky soil with wood (Yarmouth), ... 2 



Brownish yellow till (Kansan), - - - - 12 



Hard blue till (Kansan), ------ 6 



Limestone, - ..-..- - - - - 4 



Total ...-.---.- 59 



In this connection it may be remarked that several of the 

 wells in the vicinity of Denmark pass through 25 or 30 feet of 

 oxidized Kansan till and enter rock without striking a blue till, 

 but exposures in ravines both north and south of the villages 



