LAND AND WATER. B9 



pressed together wlien wet, it has the peculiar tendency 

 to form hard hinips, requiring considerable labor to 

 pulverize them and provide a fine secd-l»cd for crops. 



4. Peaty ^ or Mucky. — This is one of the most valu- 

 able kinds of soil for agricultural purposes. It consists 

 of a mixture of ordinary soil with large quantities of 

 vegetable mold. It has great power to retain moisture 

 through periods of dry weather. It contains large sup- 

 j)lies of some kinds of plant food, which are gradually 

 converted into suitable form to meet the demands of 

 successive crops year after year. 



■ 5. Lhny^ or Calcareous. — Most soils contain some 

 lime. In some cases the ([uantity is so large as to give a 

 name to the soil. The variety of s<.)il called marl con- 

 tains large quantities of carljonate of lime. 



The lime in soil serves to some extent as food for 

 plants, as all plants require a small quantity of it. It 

 also serves a good purpose indirectly, as a base, by com- 

 bining with acid substances in the soil, and forming salts 

 which are desirable as plant food. 



6. Loam. — This is simply a general name applied to 

 ordinary soil, which contains a mixture of the varieties 

 mentioned, combined in varied proportions. If quite 

 sandy, it is called sandy loam ; if quite clayey, clayey 

 loam. 



QUESTIONS. 



What was the ori2;inal condition of the earth ? How did the surface 

 become solid ? What is the present condition of the interior of 

 the earth? How do we know it? Wliat caused the appearance of 

 water upon the earth ? How old is the earth ? 



How were the continents formed? Explain the ori<iin of mountain 

 ranges and hills. Of what is soil lai-;j;ely composed? How has it 

 been formed? Give the history of most of our present rocks. 



