D. ORGANIC CONSTITUENTS. 



1. Volatile Matter. 



The volatile matter, which in the present instance includes thr 

 organic matter and water of constitution, is reported in table 52. There 

 is very little difference in the amounts found on the two drifts when 

 the comparison is made between the various sections on the two types 

 of the Carrington series, but a very wide one is observ^ed when the sur- 

 face 6-inch section of the Fargo silt loam is taken into consideration. 

 On the Kansan this rises to 20.34 per cent as compared with 11.68 ])er 

 cent on the Late Wisconsin. 



Table 52. — J'olatilc matter in the ditfrrciit scrtiaiis. 



Depth 

 Inches 



1— 6 

 7—12 



13—24 

 25—36 



Average 



1—36 



Carrington silt loam 

 Kansan Late Wis. 



per cent per cent 



10.52 

 8.58 

 6.07 

 3.73 



l-'argo silt loam 

 Kansan Late Wis. 



lier cent i)er cent 



Carrington loam 

 Kansan Late Wis. 



per cent per cent 



6.45 



5.64 



7.94 



7.16 



6.41 

 3.73 

 3.32 

 2.66 



3.68 



6.71 

 4.15 

 3.77 

 2.89 



4.03 



The course of the streams before the Late Wisconsin glaciation 

 was in a general southwesterly direction, but the ice. and later the drift 

 material left behind, blocked the previously existing drainage channels 

 and forced the water to find outlets to the southeast. Before these new 

 channels were fully developed the drainage was verv incomplete and 

 undoubtedly large areas were covered by standing water part of the 

 season. The surface material carried by the water from the surround- 

 ing highlands was thus deposited on the lowlands. Organic material 

 accumulated through the growth of dense lowland vegetation and the 

 deposition of the remains of this. Little or no peat was formed on this 

 drift. 



On the Late Wisconsin the poorly drained areas were not as 

 numerous as on the older formation and such as existed were more in 

 the form of "pot holes" in which the conditions for the formation of 

 peat were favorable, so that in most instances we have the Fargo silt 

 loam as a narrow band between the low lying peat areas and the upland 

 soil. Further, the high land did not have the black surface soil which 

 remained on the unglaciated Kansan from the as yet unnamed inter- 

 glacial interval preceding the Late Wisconsin, and hence, the eroded 

 material accumulated in the lower lying areas was not so rich in 

 oreanic matter. 



