61 



and third foot-seclions is relatively darker. With this type the grays 

 characterize the third foot-sections on the Kansan, heing^ absent from 

 a majority of the fields on the Late Wisconsin, a condition just the 

 opposite to what prevailed on the Carrinyton silt loam. This may be 

 attributed to the obstructed drainati^e, mentioned above, on the older 

 drift, the water table beinij relatively close to the surface, this exclud- 

 ing the air and preventing any considerable oxidation of the iron 

 compounds, while on the younger formation this type is confined to 

 more or less narrow^ bands around the lower lying areas and conse- 

 quently does not have the water table as near to the surface. 



Carrington Loam. The remarkable similarity between the two 

 drifts characteristic of the soils of this type already mentioned extends 

 to the color also (Table 61). With the exception of Field I on the 

 Kansan, there is little variation within the individual fields, either 

 from field to field, or from drift to drift. 



Marshall Silt Loam. There is little variation in color between 

 the soils from the two sets within the same field (Table 62) but, as 

 with the chemical composition, there is a marked difference between 

 the three forested fields, T, II and III, and the two cleared ones, IV 

 and V. On the latter the effect of the accumulation of organic matter 

 has reached as far as the third foot, causing a darker shade than if 

 found in the corresponding level in the forested fields. 



Discussion. The averages for the five fields on the different types 

 on the two drifts are shown in Table 63. There is little difference 

 in intensity of color between the soils of any one type on either drift, 

 and none at all. if we except the surface 6 inches, on the Carrington 

 silt loam and the second and third foot-sections on the Fargo silt 

 loam. In the case of these exceptions the color of the soils on the 

 Late Wisconsin is darker, indicating a condition just opposite to 

 that reported by Burke and Kolbe (11, p. 21), who presumably refer 

 to the surface soil when they state that "the Kansan drift has generally 

 a darker color than the Wisconsin." 



Table 63. — Relative shade of color. The data are the averages for the fire 

 fields reported in tables 59 to 62 inclusive. 



Depth Carrington siH loam Fargo silt loam Carrington loam Marshall silt 



Inches Kansan Late Wis. Kansan I.ate Wis. Kansan I. ate Wis. loam 



1—6 2 1 1 1 3 ?, ;, 



7—12 2 2 1 1 4 4 5 



13—24 3 3 3 2 6 6 6 



25—36 6 6 8 4 7 7 6 



Average 



1—36 4 4 4 2 5 5 5 



