Teachers' Leaflet. 



563 



Such may be omitted for when doctors disagree, how are boys and girls 

 to know? 



LESSON CXXXIL 



HOW SOILS ARE MADE. 



Purpose. — To show how organic soil was first produced in Geologi- 

 cal times and became mixed with the stone flour. Also to identify lichens 

 growing on rocks, trees, fences and barns. 



As I said before, soil is stone flour and organic matter mixed. Here 

 comes a puzzling question. After the glacier had passed and nothing 

 but stone flour lay over the face of the earth and that as infertile as the 

 stuff from the bottom of a well, how was vegetable matter to begin 

 to grow? 



Let every member of your class take another field excursion for an 

 inspection of rocks for the purpose of learning how organic life began. 



A 7'ieiv over the hummocky surface of a part of the Moraine of the great American 



ice sheet in Central Nezv York. 



Examine the field rocks or a stone wall and study it closely. Search for 

 little cavities where some flour may be found, perhaps less than a thimble 

 full. By careful observation, growing threads or specks of lichen may 

 be found growing from that small portion of stone flour. The amount 

 may be that small as not to give shade to a lady bug, but that makes no 

 difference, it will show the process of soil formation. That tiny bit of 

 lichen — your pupils may call it moss which gains its nourishment from 

 the air and rain — will not remain there forever. The time will come when 

 like all other growing things it must die and find a grave in that thimble 

 full of stone flour. No matter, the small cavity in the rock will hold 



