58 NATURE AND PROPERTIES OF SOILS 



regions dairying has been developed to a large extent, while 

 in certain localities, where climate, soil, and market are fa- 

 vorable, trucking is of great importance. 



32. Effect of glaciation on agriculture.^ — In comparing 

 glaciated soils with corresponding residual areas, certain 

 differences are usually apparent. The agricultural condition 

 within the zone of glaciation is usually consistently higher 

 than that beyond the regions of drift accumulation. The 

 extensive leveling due to glacial erosion and deposition has 

 almost always resulted favorably for agricultural operations. 

 Even the thickness of the drift is found to conserve the 

 ground water supply. While it is difficult to show any con- 

 sistent difference between residual and glacial soils as to total 

 constituents, it is generally admitted that glaciation has been 

 a benefit to agriculture, in that the soils have been rejuven- 

 ated and their crop-producing power raised. 



The dominant textural quality of glacial soils seems adapted 

 to certain staple food crops, and, due to their interming- 

 ling, a considerable opportunity for diversified and intensi- 

 fied farming is offered. It is, therefore, evident that in any 

 study of soils, particularly those of the United States, a 

 careful consideration of the effects of glaciation is neces- 

 sary. Even the alterations in topography are factors not 

 to be ignored. In a comparison of the driftless area of "Wis- 

 consin with the glaciated parts only 43 per cent, of the 

 former is improved as against 61 per cent, of the latter, while 

 the value of the farms on the glaciated soil averages 50 per 

 cent higher. The same general differences appear between 

 the glacial and residual soils of Indiana and Ohio. 



33. Lacustrine soils — glacial lake. — Great torrents of 

 water were constantly gushing from the front of the great 



* Whitbeek, R. H., The Glaciated and Driftless Portions of Wisoonsm; 

 Bui. aeog. Soc. PML, Vol. IX, No. 3, pp. 10-20, 1911. Von Englen, 

 0. D., JSffects of Continental Glaciation on Agriculture; Bui. Amer. 

 G-eog. Soc, Vol. XLVI, pp. 353-355^ 1914. Ames, J. W., and G-aitlier, 

 E. W., Soil Investigations; OMo Agr. Exp. Sta., Bui, 261, 1913. 



