24 



Marshall Sill Loan. This type has developed on a loessial fornin- 

 tion and accordingly it would not be expected to carry many, if any, 

 fragments coarser than 2mm. The thickness of the deposit might have 

 an influence on the number of these since, in case it were shallow, bur- 

 rowing animals and insects might carry upward a sufficient amount of 

 the underlying till to modify to a certain degree the mechanical, if not 

 the chemical composition of the soil (21, p. 90-91 V 



On one field, I (Table 11) and in the first set from another, III, 

 the till was encountered in the third foot-section, Set 2 of the latter 

 field being evidently entirely on the till, since it carried as high a per- 

 centage of coarse fragments as any field on the Carrington loam. The 

 amounts found in the two sets on this field are given below : 



The large area of this kind of soil west of Nerstrand, upon which 

 Fields I and IIT are located has a very shallow deposit of loess (11, p. 

 36.), while that to the north and east, upon which sites for Fields II, IV 

 and V were selected, appears to have a greater thickness and accord- 

 ingly is more representative of this type. Few fragments were found 

 in the samples from the three fields last mentioned. 



Tabic II. — Coarse gra^'cl in the different sections froui the Hve fields on 

 Marshall silt loam. 



Tabic 12. — Average wciglit of coarse tira-rel /mrlieles in the different sections 

 from the five fields on Marshall silt loam. 



