BLUFF SECTIONS l39 



Kansan, several feet exposed. 



Oxidized band, 6 to 8 inches. 

 Aftonian sand (probably), 20 feet. 



Nebraskan, typical, several feet exposed, its top 30 feet above the 

 river bottoms. 



This section is opposite a gravelly bench or terrace, which is covered at 

 least in part with Kansan drift. 



8. Exposure in section 1, township 99 north, range Jf9 luest. — This 

 exposure is located in Lyon County, Iowa, in the rugged bluffs, the 

 southern portion of which is represented in plate 7, figure 1. There 

 was here evidently much plowing of the Aftonian sand by the Kansan ice, 

 for the former has been forced up to a height of 140 feet above the val- 

 ley. Kansan rises above this for at least 35 feet. Xebraskan rises to a 

 height of 125 feet in these bluffs and springs appear above it. 



9. Banhson hluff section. — This is located in the northeast quarter of 

 section 2, township 99 north, range 49 west, on the face of the river 

 bluff, and is nearly opposite section 8. 



Kansan, weathered on exposed faces, probably 35 feet. 

 Aftonian : 



Coarse sand and fine gravel, 8 feet. 



Conglomerate, 3 feet. 



The conglomerate is aboift T5 feet above the valley, and a fine spring 

 discharges above it. 



10. Banl'son cellar and well section. — This is of especial interest be- 

 cause it is on the great plain which extends from Shindlar to Canton, 

 and shows the structure of what had probably been formerly included in 

 a Wisconsin plain. 



A well and cellar dug near the residence of Mr. Bankson show the 

 following : 



Soil and yellowish weathered Kansan, 2^ feet. 

 Kansan, typical, 7^ feet. 

 Aftonian : 



Sand, about 1 foot. 



Conglomerate, thickness unknown. 



Springs flow from about the level of the conglomerate on the gentle 

 slope of the hill. 



11. Spring dale township sections. — These sections, three or four in 

 number, are located on the west side of the Big Sioux above the Cliicago, 



