32 



In Field I on the Late Wisconsin, the carbon dioxide ranged from 

 2.23 per cent in the surface section to 3.99 in the third foot, this field 

 being- the richest in carbonate of all thirty-fi^'e fields sam])led. ( )f the 

 four other fields, TV is the only one showing- an aj^ipreciable ([uantit}-, 

 this carrying- 1.03 per cent in the third foot-section. The others aver- 

 age less than 0.1 per cent for the three feet. With this type in general, 

 carbonates are higher on the Kansan than on the Late Wisconsin, the 

 average for the latter being high only because of the large amount in 

 Field^I. 



Table 22. — Carbon dioxide in the different scelions fruiii the five fields on 

 I'argo silt ioain. 



2. Late Wisconsin. 



1— 6 2.230 



7—12 2.410 



13—24 2.500 



25—36 3.990 



Average 

 1—36 2.937 0.071 0.072 0.383 0.032 0.697 0.701 



Subsequent to the collection and analysis of samples from Field 1 

 it was established that although it appeared, on first inspection, that 

 the drainage outlet was lower than the lowest point in the tract, in 

 reality it was some feet higher, the field thus forming a part of an 

 extensive but very .shallow "pot-hole." The drainage water accumu- 

 lating" in the lower part of this and evaporating- would leave behind the 

 mineral constituents leached from the surrounding- uplands, thus bring- 

 ing about a concentration of these, and as the drift was so well sup- 

 plied with limestone the carbonate content of the soil of this field was 

 raised to a high point. 



Carrington Loam. The quantity of carbonate in the Carrington 

 lo.im varies but little from field to field and is practically nil on both 

 drifts, the soil having been thoroughly leached to at least three feet 

 even on the Late Wisconsin (Table 23). 



Discussion. The average amounts of carbon dioxide for the five 

 fields on the different types on the two drifts are shown in table 24. On 

 the Late Wisconsin the averages in the three foot section are higher 

 than on the Kansan with the exception of those for the Carrington 



