44 



'J able 



-Composition of Carrington loam. 



SiOa 



AI2O3 



FesOa ....:... 



AlgO 



CaO 



Na20 



K2O 



TiOo 



P20fi 



CO2 



Volatile matter 



Si02 



AI2O3 



Fe203 



MgO 



CaO 



NaoO 



KoO 



TiOo 



P20r> 



COj 



Volatile matter 



The silica (Table 3S) is quite uniformly distributed on the two 

 drifts, the amounts differing slightly, however, from type to type. The 

 lowest averages are those for the Fargo silt loam and the highest those 

 for the Carrington loam. On the Kansan, the former, in the first 6-inch 

 section, shows only 59.05 per cent, but this does not appear so strange 

 when we take into consideration the fact that this soil carries over 20 

 per cent of volatile matter. On the Kansan, the maximum appears in 

 the lowest section, while on the Late Wisconsin it is reached in the 

 second foot or the lower half of the first. The soils on the youngei 

 drift are, on the average, somewhat richer in silica and the maximum 

 amount is found at a higher level. 



Depth 

 Inches 



1— 6 



7—12 



13—24 



25—36 



Averaa 



1—36 



Tabic 38. — Silica in the different sections. 



Carrington s;!t loam Fargo silt loam Carrington loam 



Kansan Late Wis. Kansan l.ate Wis. Kansan Late Wis. 



per cent per cent per cent per cent per cent per cent 



72.b3 



74.05 



69.18 



68.08 

 70.42 

 72.02 

 71.97 



71.08 



75.69 

 77.05 

 74.95 

 78.23 



76.52 



76.34 

 77.37 

 76.26 

 76.08 



76.70 



