182 Lessons in Nature Study. 



We will call it subsoil, or undersoil. What else do we 

 sometimes find in digging ? Oh, yes, and stones are hard to 

 dig out when they are large. Are stones living things ? 

 Oh, no, there is no life in them. They are pieces of rock 

 broken off and buried in the soil. Can you tell me any- 

 thing which stones can be used for ? Oh, yes, we use them 

 for building foundations of houses. Some kinds of stones 

 are very valuable. We call them precious stones. Do you 

 not know any other valuable things that are taken from the 

 ground ? Oh, iron, copper, gold, and silver are dug out 

 of the ground. Stones and other things dug from the 

 ground are called minerals. 



Minerals Metals. 



Some minerals, like gold, iron, silver, copper, and zinc, are 

 called metals. 



Quarrying. 



The getting of stone out of the ground is quarrying. 

 Some of you have seen a stone-quarry. Others dig down 

 very deep after the metals. These men are called miners, 

 and what they do is called mining. Let us now look at 

 these pieces of stone ; they were dug out of a cistern. Are 

 they not all alike ? See how the outside of these stones is 

 softer and lighter than the inside. That is because these 

 stones are becoming softer and wearing away from the out- 

 side. The rain and frost help to tear away the little pieces 

 from the outside of the stones. We call it weathering, be- 

 cause the weather makes the stones rot. If you go to a 

 hillside where there has been a deep cut made, you will 

 often see top-soil, then subsoil full of pieces of stone, then 

 the rock underneath. The frost has broken off pieces from 

 the rock, and these pieces are the stones in the subsoil. 



Soil and Subsoil. 



We will dismiss ten minutes earlier, as I want you to go 

 up on Long Hill to-day, at the close of school, where Mr. 

 Doran is grading down the street. 



