CHAPTER I 



THE SOIL AND ITS ORIGIN 



What Soil Is. — In its broad meaning, soil is that friable, upper 

 stratum of the earth composed for the most part of mineral matter 

 resulting from the breaking up and decay of rocks. It extends to 

 sohd rock — varying in depth from an inch or so to many hundreds 



FiQ. 1. — A spiral nekiula. It is believed that the earth was at one time a revolving mass of 



gaseous material. 



of feet. Mixed with this mineral matter/ especially at the surface, 

 is more or less organic matter incorporated through the subsequent 

 growth of vegetation. 



Soil Is Forming All the Time. — The fact that soil is derived 

 from rocks implies that it is one of the later products of creation. 

 All soil, however, was not formed in some particular period in the 

 early history of the earth — some of it was formed millions of years 

 ago and some is being formed today. 



1 Generally speaking, mineral matter is any substance not formed by plants 

 or animals. Organic matter is any substance formed by plants or animals. 



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