21 



The percentaq-es found for the Late W iscoiisin are, on the aver- 

 ao^e, 280 per cent hig^her than those for the Kansan. It is evident from 

 this that the processes of weatherini,^ are the more advanced on the 

 older de])osit. An examination of the i)articles shows that shales, lime- 

 stones, and cherty rocks are much more abundant on the voune^er for- 

 mation, having- practically disappeared from the older. 



For this type the average weight (Table 6) of the gravel particles 

 brought up by the auger is very uniform, showing little variation from 

 field to field or from drift to drift. 



Table 6. — Average i^.'eight of coarse grgrel f'artirlrs in I he different sections 

 from the fize fields on Carringtoit silt loam. 



Field Field Field Field Field Average for 



Jiepth I II III IV V 5 fields 



Inches granus grams grams grams grams 



grams 



1. Kans.\n. 



1— 6 .022 .022 .043 .020 .018 .02.^ 



7—12 .019 .031 .043 .020 .064 .035 



13—24 .017 .020 .031 .016 .023 .021 



25—36 .043 .021 .044 .024 .032 .033 



.Vverage 



1-36 .027 .022 .039 .020 ' .032 .028 



2. Late Wisconsin. 



1— 6 .020 .045 .037 .026 .065 .039 



7—12 .018 .032 .024 .031 .027 .026 



13—24 .024 .010 .027 .028 .031 .024 



25—36 .020 .023 .027 .022 .027 .024 



Average 



1—36 .021 .024 .028 .026 .035 .027 



Fargo Silt Loam. The general distribution (Table 7) of coarser 

 fragments is much the same as on the Carrington silt loam, the maxi- 

 mum being in the third foot and on the average only 25 per cent as 

 much on the Kansan as on the later formation. On the former, three 

 fields, T, III and V. show little or no coarse gravel in the surface foot, 

 while only one, II, shows as much as 1.0 per cent in the lowest section. 

 On the Late Wisconsin the range is from 0.23 per cent to 4.38 per cent, 

 with an average of 1..^0 per cent for the three foot section on the five 

 fields. 



riie average weights for the gravel particles ( Table 8) are quite 

 similar both from field to field and on the two drifts. The second foot- 

 section from Field III on the Kansan shows the highest average of all 

 the field samples, but this was due to the inclusion of several stones 

 larger than those one is ordinarily able to bring up with the auger. 



