540 



IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



D. Grayish brown calcareous clay, somewhat jointed, highly iron 



stained along the joints; grading into (B) rather sharply.... 20 



C. Yellowish gray clay, highly calcareous; contains small bowl- 

 ders, and grades gradually into (D) 20 



B. Yellowish gray clay grading into bluish black jointed clay be- 

 neath ; highly calcareous 30 



A. Dense, fine-grained bluish black, jointed clay; contains small 

 quartz pebbles and pieces of wood; is highly fossiliferous; to 

 the water's edge 2 



Horizons B, C, D, E are Wisconsin drift lying on what is un- 

 questionably Yarmouth interglaeial deposits. North of the river 



Fig. 171 



at this point, figure 170, are two terraces, F and G. A section in 

 the drift material of- the upper terrace revealed a thick deposit 

 of peaty soil, filled with shells. The material of the upper 

 terrace is unquestionably Wisconsin in age snd was deposited 

 in a lake which filled this valley during the retreat or advance 

 of the Wisconsin ice. Following the valley of Lime creek east- 

 ward, it was found that the peaty 'material disappears and a 

 thin covering of drift is visible. An examination of the drift 

 shows it to be very much like lowan drift. Light colored bowl- 

 ders may be seen similar to those so common on the lowan drift. 

 If lowan drift is present in the valley where the section in 

 figure 170 is given, it is impossible to tell it. It may be that the 



