Rocks and Soil 309 



18. What facts or principles stated in this chapter apply to the care of a 

 home garden? 



19. Why does spreading dry leaves or straw over the soil protect plants 

 during drought? 



PROJECTS 



1. Make a collection of different types of rocks, labeling each to show 

 its character, its general uses, and the locality from which it came. 



2. Make a collection of as many different kinds of soil as you can find 

 in your neighborhood. Label each specimen with its general class, 

 title, and the locality where found. 



3. Make a wooden mold and prepare and cast a cement block. 



4. Make a brick from materials in your neighborhood and bake it in the 

 home oven. 



OUTDOOR OBSERVATION 



1. Observe and list all construction uses of (a) stone, (b) cement, (c) 

 metals, noted on your way to and from school. 



2. Observe the mixing and placing of cement and concrete, or the erec- 

 tion of iron work on some structure. Record your observations. 



3. Observe the different layers of soil or rock which have been exposed 

 by weathering or erosion on a hillside or along a stream. Record 

 your observations. 



4. Dig a small hole in your yard to a depth of three feet, removing the 

 earth carefully and noting the changes in the character of the soil and 

 the thickness of the different soil layers. Make a labeled sketch and 

 record your discoveries. 



REFERENCES 



Common Minerals and Rocks Crosby 



Soil Fertility and Permanent Agriculture Hopkins 



