40 

 6. Relation of Calcareousness to Texture. 



The variation in texture of the samples from the four types used 

 in this study, as expressed by the moisture equivalents (Table 20). 

 varies rather widely, the highest average for a type being 32.2 and the 

 lowest 21.0. Each type was found to have practically the same texture 

 on both drifts. 



One relation between the texture and calcareousness should be 

 pointed out. The Fargo silt loam, which on both drifts has the fines! 

 texture, still has carljonate in the surface six inches. The Carrington 

 silt loam, next finest in texture, still has carbonate present in the second 

 and third foot-sections on the Late Wisconsin. l)Ut none on the Kansan, 

 while the Carrington loam, which has the coarsest texture of all the 

 type studied, shows no carbonate in the first three feet on either drift, 

 the leaching having carried it below this level even on the more recent 

 formation. However, it should be borne in mind that the first-named 

 type has the most imperfectly developed natural surface drainage and 

 the last the best, the Carrington silt loam occupying an intermediate 

 position. 



7. Relation of Calcerousness to Age of Drift. 



As pointed out above the texture of the soil on each of the three 

 types is quite uniform from drift to drift. So, any difference in the 

 amount of calcium carbonate between soils from any one type on the 

 two drifts must be due, not to difference in texture and hence to differ- 

 ences in the rate of percolation, but to the age of the drift. In the 

 samples from the Fargo silt loam carbonate is found on both drifts and 

 no difference in the degree of leaching is shown. On the Carrington 

 loam the carbonate has been leached out of the first three feet on both 

 drifts, so that it is only in the soils from the Carrington silt loam that 

 any relation between the calcareousness of the soil and the age of the 

 drift will be apparent. In the soils from this type on the Kansan no 

 carbonate is found above the three foot level but in the majority of 

 fields on the Late Wisconsin it occurs in the third foot-section and in 

 some instances in the second, indicating that leaching has proceeded 

 farther on the Kansan. 



