54 THE PRINCIPLES OF SOIL MANAGEMENT 



different physical properties, from different parts of 

 the United States. Many of these analyses are less 

 complete with reference to some of the plant-food con- 

 stituents than is desirable for the purpose here intended. 

 So far as possible, analyses of the entire soil have been 

 used, but, where these could not be obtained, analyses 

 of the strong hydrochloric acid extract are given. 



20. Ice glacial soils. In many parts of the world 

 there exist soils which have been formed under the 

 influence of large bodies of ice. 



In earlier times, masses of ice extended far to the 

 southward over the country now devoted to agricul- 

 tural purposes. Around the world this mass of ice 

 appears to have extended down from the north and 

 south poles to a zig-zag limit. It reached into Asia, 

 Central Europe and the American Continent as far 

 south as New York City, Cincinnati, St. Louis, Kansas 

 City and Omaha, and farther west in the Puget Sound 

 region it extended south across the Columbia river. 

 All the country north of this line with the exception 

 of one or two small areas was covered by an immense 

 sheet of ice which moved slowly down from the north- 

 ward. In the southern hemispheres are similar though 

 more limited traces of the same condition. 



The depth of the ice was so great that it flowed 

 over such elevations as Mount Washington in New 

 Hampshire and over the Adirondacks in New York. 

 Its general movement in the northern hemisphere was 

 southward. Its flow was modified by the original topog- 

 raphy of the country, but its depth was so great it 

 was able to disregard and override many of the land 



