IOWA ACADEMY OF SCIENCES. 83 



struck into a valley cut into the Kansan drift, while the other 

 well entered the Kansan drift near the level of the bordering 

 uplands: 



SECTION OF WELL AT F. SMITH'S, NEAR YARMOUTH. 



FEKT. 



Yellow till (Illinoian) 36 



Sand with thin beds of blue clay and also of 



cemented gravel 73 



Black muck containing wood 6 



Sand and gravel, probably alluvial 8 



Gray silt nearly pebbleless, apparently alluvial. . . 15 



Blue till (Kansan) 42 



Total depth 180 



If my interpretation of the records at Yarmouth is correct 

 there is here not only a notable accumulation of peat and muck 

 between the Kansan and Illinoian, but also an erosion of the 

 Kansan till sheet to a depth oi forty feet prior to the deposi- 

 tion of the Illinoian. Since these sections are based entirely 

 upon well records they afford a less clear idea of the relation 

 of the beds than might be afforded by valley excavation. 



EXPOSURES IN NEIGHBORING DISTRICTS. 



One of the most satisfactory exposures yet found is that 

 afforded by a ravine about one mile northeast of West Point, 

 in Lee county. This was first seen by the writer in 1894. The 

 following section may be obtained by descending the gully at 

 the roadside; 



FEET. 



Surface silt (loess) 6 



Black soil with ashy gray subsoil 5 



Brown till containing many bowlders, among 

 which were two red jaspery conglomerates 



(Illinoian) 15 



Black mucty soil with gray subsoil (Yarmouth). ... 6 



Brown clay with few pebbles (Kansan) 15 



Total 47 



This exposure was visited by Prof. 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 



