50 TALKS ABOUT THE SOIL. 



Among the igneous rocks are the granites, sienites, 

 basalt, trap-rocks, porphyry, lavas, and volcanic stones. 

 Among the organic rocks are chalk, coal or stone 

 formed from the remains of plants, and limestones 

 formed from the remains of minute creatures from the 

 sea. The sedimentary rocks may include materials 

 from every one of these. The shales and sandstones 

 come from the remains of weathered rocks worn down 

 into mud and sand, and re-formed into rock. 



Rock itself, whatever its character, is not a soil. 

 Even when broken up and sorted out into gravel, it is 

 not a true soil. Only the sands and fine silts make the 

 real soils of our fields and gardens. It is plain, that 

 this process of weathering, sorting, and forming into 

 sands and silt, has been going on a long time, and that 

 vast quantities of the material have been turned to 

 sandstones and shales : the original materials of the 

 soils must by this time be therefore completely mixed 

 together. This is true, and from this comes in part 

 the great variety in all our soils. All this weathering, 

 tearing down, transporting and sorting in streams and 

 rivers, has been going on for countless ages upon ages. 

 The land has sunk in the seas, only to rise again and 

 be cast up as mountains. The very floor of the sea 

 has been bent and doubled up to form lofty hills. Ice, 

 floods, glaciers, earthquakes, and terrible storms have 

 mixed the rocks, sand, and silt in hopeless confusion. 

 It is quite useless to think we can tell much about any 

 particular soil in our fields, from the rocks in the hills 

 near by, or deep under the soil itself. All we can do 



