34 Effective Farming 



Such lake-formed soils are known as lacustrine and are of two 

 kinds, -those made by recent lakes and those by glacial lakes. 

 Large deposits of glacial lake-formed soils are found in the 

 United States. The fertile Red River lands in Minnesota are 

 largely of this soil. The recent lake deposits are formed when 

 the lakes are filled by river sediment. The area of such soils 

 in the United States is small. Lake-formed soil is usually 

 rich in humus, fine, and of good tilth. 



Glacial soils. The soils that were formed by the glaciers 

 that covered the continent in prehistoric times are usually rich, 

 fertile, of good tilth, and produce good crops. They extend 

 over several of the best farming states, including parts or all 

 of Montana, North Dakota, South Dakota, Iowa, Illinois, 

 Wisconsin, Michigan, Minnesota, Indiana, Ohio, Pennsylvania 

 New York, and the New England States. Much of the corn- 

 belt is glacial soil. 



JEolian soils. Those soils that have been deposited by the 

 action of the wind are called a3olian. The principal agricultural 

 soil of this kind is loess, which is generally thought to be wind- 

 blown material from accumulation of sediment carried and 

 deposited by rivers in front of the prehistoric glaciers. Loess 

 is found in great abundance in certain areas of the Mississippi, 

 Missouri, and Ohio valleys. It is very rich and in the Central 

 States is especially valuable for corn-growing. 



Sand dunes are wind-blown hills that are not valuable for 

 farming purposes. They are coarse-grained, contain little 

 organic matter and are constantly shifting from place to place. 



15. Classification of soil according to texture. By tex- 

 ture is meant the size of the soil particles. These vary from 

 those that are invisible without the microscope to large rock 

 fragments. Even a fine-grained garden soil is made up of 

 several sizes of particles, which may be proved by stirring 

 a small quantity in a tumbler of water and allowing it to settle. 

 The coarser particles will settle at the bottom ; and the finer 

 above them ; the very finest may not settle for several hours. 



